Bird Behaviors

Nesting Behaviors of the Tufted Titmouse in USA

Tufted Titmouse Perching
Image by Mike Nolan via Flickr.

The Tufted Titmouse. Is it a tit (the bird, just to be clear)? Is it a mouse? 

Well, neither. 

It is a small passerine bird, related to the chickadee family. 

A regular to backyard feeders of Eastern USA, the tufted titmouse can be seen flitting around the outer branches of deciduous woodlands. 

Like the Eastern bluebird, the tufted titmouse is a cavity nester. They nest in both artificial and natural structures. 

This article will aim to explore the nesting behaviors of the tufted titmouse.

What Are Tufted Titmice?

The tufted titmouse is a species of passerine bird found across much of the Eastern woodlands of the USA. 

Although small, roughly 6 inches long, it looks comparatively larger than other passerine species that frequent bird feeders – even though it’s not. This is often attributed to their large heads and full-bodied appearance. 

Their size, coupled with a few distinct facial markings, are characteristics that separate them from similar species, such as the chickadee. 

Tufted titmice have large, dark eyes, along with a pronounced gray crest. From above, they have a uniform gray coloration. From below, their feathers are mostly white with streaks of pale orange. 

Above their short, stubby bill, and between their eyes, a distinct patch of black feathers can be found. 

There may be ID confusion when comparing the tufted titmouse to another titmouse species – the black-crested titmouse. As the name suggests, the black-crested titmouse has a fully black crest. 

Close Up of Tufted Titmouse
Image by Jay Gao via Flickr.

Geographical Distribution of the Tufted Titmouse

The tufted titmouse can be found in the Eastern United States, from Texas to Maine, typically in forests, both evergreen and deciduous, below 2,000 feet. 

In this relatively large geographical range, tufted titmice remain year-round. Unlike other passerine species, they are non-migratory and typically stay in the same region as they breed. 

With a warming climate, it has been observed that the range of the tufted titmouse was gradually expanded Northwards. 

During the early 20th Century, the tufted titmouse could be observed in the state of New Jersey. This, at the time, is the most northely record of the small passerine. 

Today, however, records from the Atlas of the Breeding Birds of Ontario, have discovered tufted titmice as far North as Quebec and Ontario in Canada.

Where Do Tufted Titmice Nest?

Like bluebirds, the tufted titmouse is a secondary cavity-nesting bird.

And for those that need a quick memory jog, secondary cavity-nesting is essentially a fancy way of saying these birds live in pre-existing holes made by other species. 

Tufted Titmice Nesting in a Tree Cavity
Image by via Fernando B. Corrada via Flickr.

In the winter months throughout the Eastern USA, the average outside temperature is little over freezing. 

So, where better than to escape the frigid temperatures? Somewhere sheltered. A cavity, for example. 

Ah, it’s all making sense now. 

However, there is one flaw to this master plan. 

Like most passerine bird species, tufted titmice have those characteristic three toes forward, one toe backward. Great for perching. Not so great for excavating their own holes. 

So, to get around this, they enlist the help of larger species, such as the Pileated Woodpecker or Northern Flicker, that have already made holes for themselves. 

But, when pre-made natural holes aren’t available, the tufted titmouse, much like the bluebird, will happily seek refuge in artificial structures, such as nest boxes, fence posts and even gutters. Talk about being resourceful. 

The nest of a tufted titmouse has been recorded as high as 90 feet into the tree canopy. 

Nest Building in Tufted Titmice

So, a female has found a suitable nesting cavity. 

Now what?

Time for decorating. 

Within the cavity, be it natural or artificial, the female tufted titmouse will build up a cup-shaped nest using a variety of substrate

Typically, most females will opt for materials such as moss, grass and twigs to build the foundations of their nest. Then, depending on the individual and availability of resources, insulation is added. This can be in the form of bark shreddings or, rather bravely, hair plucked from a living animal.

Once a female is suitably satisfied with her creation, copulation can begin. 

Tufted Titmouse With Nesting Material
Image by Kitty Kono via Flickr.

Copulation in the Tufted Titmouse

Copulation in tufted titmice is rarely observed so research in this field is few and far between. 

Like many bird species, copulative behavior is restricted to a relatively narrow period during the early part of the breeding season. This is typically during very late March and April. 

Over the duration of the nest building, the male tufted titmouse will remain close by. He will regularly flutter his wings, not only to advertise his mating needs, but also to ward off any rival males. 

Only when nest construction is complete will the female titmouse emerge from the cavity. With the male waiting on a nearby branch, the female flies directly towards him. 

Studies in the field, carried out by Matthew Halley, observed the male flitting between nearby branches, with the female following his every move.

After a while, the female also began to vibrate her wings. This is known as the “flutter display”. The male, if interested, returned the wing vibration and copulation would commence soon after. In addition to the rapid wing vibration, the female may produce a series of high-frequency notes.

Tufted Titmouse Nesting Behaviors

A Tufted Titmouse in a Artificial Nest Box
Image by Mike Smith via Flickr.

In a recent study, it was observed that the tufted titmouse exhibited interspecific nest usurpation

Again, what’s with the names, scientists?

In short, interspecific nest usurpation is whereby one bird species takes over the nesting site of another bird species. 

Although this behavior is relatively common within secondary-cavity nesting birds, it has never been recorded in the tufted titmouse. 

Until now. 

Perhaps due to increased competition in response to habitat loss, the tufted titmouse observed in the study evicted a bluejay from a cavity. However, instead of letting the eggs of the bluejay perish, the tufted titmouse incubated these eggs until they hatched. 

The rearing of non-conspecific nestlings is an odd behavior, so why did the tufted titmouse do it? 

Well, scientists don’t really know. 

To rear another species is deleterious to the survival of one’s own health, as significant costs are incurred. 

So, one of the most likely explanations is that the tufted titmouse simply doesn’t realize it’s doing so. When the nesting desire is so high, the brooding female gets into a nesting “zone” and will incubate her own eggs, as well as the eggs in the recently usurped nest. 

How Humans Can Help

Like the Eastern bluebird, which has thrived from the help of human intervention, the tufted titmouse has also prospered in recent years. This is especially the case in suburban parks and recreational grounds, where the installation of bird boxes has guaranteed a safe place to nest, away from the prying clutches of predators. 

Of course, as with much of our wildlife today, threats do still occur. For the tufted titmouse, and many other small garden feeders, the presence of domesticated cats is having an impact on populations. Cats are skilled hunters, with an estimated 38% of the hunts ending in kills

One of the simplest solutions to prevent wildlife being killed by domesticated cats is to attach a bell to the collar of your cat. As the cat approaches its prey, the motion will cause the bell to emit noise, warning any species in the vicinity of the potential predator. 

Another problem facing many passerine bird species, including tufted titmice, is glass; mostly in the form of windows and doors. 

According to a 2014 study, over 1 billion birds perish from flying into windows each year. And the tufted titmouse is no exception. 

It makes sense though. I mean, windows reflect surrounding foliage and sky, thus luring the flying birds into a false sense of security. Then, out of nowhere, bam! 

If you’re prone to pesky mosquitoes in your area, perhaps invest in some mosquito netting on the outside of the windows. Not only will this screen protect you from irritating bites, they also reduce glare and reflection, discouraging birds from flying into windows. 

The above remedies are ways humans can save birds themselves.

But how can we increase the breeding population of tufted titmice?

Like the bluejay, the tufted titmouse is an adaptable nester, and can successfully rear a brood in an artificial nest box. 

Before the breeding season, and ensuring that you have an entrance hole of just over an inch in diameter, you can install a nesting box up to 15 feet high on a pole or tree, preferably in areas with deciduous trees. 

Final Thoughts

Tufted Titmouse in a Tree Cavity
Image by via Louis Ruttkay via Flickr.

The nesting behaviors of Eastern bluebirds and tufted titmice are relatively similar. 

Both are secondary-cavity nesting birds. 

Both can thrive in the presence of humans. 

However, like with many other species in our rapidly changing planet, the tufted titmouse needs a helping hand to ensure further breeding successes. 

The easiest way to help is through the installation of nest boxes. Typically, these inexpensive structures have “goldilocks” holes – just the right sized entrance hole to allow the tufted titmouse in and non-native bird species out.

Bird Behaviors

How Do Birds Sleep?

It may come as a surprise to some, but yes, birds do sleep. 

Sleep is essential when it comes to avian cognitive development, including early development, in birds. 

But how do they sleep?

A Sleeping Macaw
Image by David via Flickr

The sleeping antics of birds differ somewhat to that of a mammal. For starters, most birds sleep in short bursts of no more than a few minutes at a time. 

Some species even sleep whilst flying. 

Birds, along with aquatic animals, are some of the only animals that are capable of shutting down just half their brain whilst they sleep. This means the other half is still aware of its surroundings, and any potential predators. 

This article aims to explore how different groups of birds, from passerines to waterfowl, sleep. 

How Do Off-shore Birds Sleep

If I ask you to think of a bird, what comes to mind?

A bluebird on a bush? A robin in a tree? 

Typically, birds are associated with some form of plant – be it a bush, a hedgerow, or a tree. 

After all, some of the most common birds found in the USA are those that live in and around gardens and suburban parks, close to trees and bushes. 

However, there are some species that spend years, even decades, out at sea. Meet the seabirds.

These birds are adapted to life on the wing. They have mastered the art of feeding and drinking whilst flying, eliminating the need to touch land. 

But what about sleeping?

Do Seabirds Need To Land To Sleep?

Well, not exactly. 

In a recent paper, it was found that frigatebirds, a tropical seabird, can stay in continuous flight for up to two months. In this time, they will stay aloft without coming into contact with land or sea. 

A Magnificent Frigatebird Flying
Image by Florian A via Flickr

However, even if they wanted to, the frigate birds couldn’t take a rest on the ocean, as they lack waterproof feathers. This means any contact with water will result in waterlogged feathers, and the risk of drowning. 

So, how do they sleep?

The paper, authored by Rattenborg, goes on to explain that data, collected via small devices attached to the birds, shows that the frigate birds do in fact sleep whilst flying. 

However, unlike land birds, which typically sleep for up to 12 hours per day for approximately one minute at a time, frigate birds sleep very little – as little as 45 minutes per day, in small 10 second bursts. 

The Science Behind Seabird Sleeping Patterns

The main theory as to why seabirds can sleep so little is to do with their brains. With the frigatebird being the species in question, scientists have identified that seabirds sleep unihemispherically.

Don’t worry, I’m not expecting you to know what that means. These pesky scientists and their unnecessarily complicated terms. 

In short, an animal that displays unihemispheric sleeping essentially shuts down half of their brain. 

A range of animals, especially aquatic mammals, display this kind of behavior. It is a way of getting some rest, whilst still being relatively aware of the surroundings. You know, in case a predator comes on by whilst you’re trying to take a nap. 

Amazingly, the eye connected to the awake part of the brain remains open, allowing birds to still visually navigate whilst sleepflying

Sleepwalking just got an upgrade. 

However, it has even been proposed that offshore birds can get a quick REM sleep cycle in, with both eyes closed! No wonder why they sleep for just 10 seconds at a time. To achieve this, the bird simply needs to maintain a state of aerodynamic soaring or a gliding position to maintain balance. 

The same principles can be allied to other long-distance offshore birds. A prime example of this is the wandering albatross, which can fly over 10,000km in a single trip. 

How Do Passerine Birds Sleep?

The passerines are perching birds. They are characterized by having four toes, three of which point forward, whilst one points back. 

Hill Blue Flycatcher Perched
Image by Khoi Tranduc via Flickr

Approximately 60% of all known bird species are classed as passerines. This includes common garden species that you may see daily, such as sparrows, cardinals and finches. 

But have you ever wondered what happens to these birds when the sun goes down? Do they even sleep? Afterall, how many of us have seen a sleeping bird?

Like most animals, sleep is essential for the development of birds. Sleep disturbances in birds have been shown to impair cognitive performance

Passerine Species Also Show Unihemispheric Sleep

In a nifty evolutionary trick, sleeping passerine birds undergo unihemispheric slow-wave sleep, or USWS for short – the same process that allows offshore birds to sleep whilst flying. 

Unlike the mammalian sleep cycle, USWS allows the sleeping bird to react quickly from a perceived threat, but still maintains satisfactory rest should no risk arise. 

It’s a complicated field of research, with scientists still trying to wrap their heads around the matter. For now, all we need to know is that passerine birds can sleep with half their brain still awake, in bursts or around 1 – 4 minutes

That’s the cognitive reasoning as to how passerine birds sleep, but what about the physiological side of things? 

Do Passerines Get Comfy When Sleeping?

Well, arguably, yes. 

Many passerine birds exhibit behaviors that make their feathers fluff up more. This is to better cover their body when they sleep and keep themselves warmer when exposed to the elements. At night, many species undergo thermogenesis, whereby they burn calories to generate heat. 

Sometimes, in extreme weather conditions, some passerine birds turn up the notch and experience a form of regulated hypothermia, referred to as nocturnal torpor. This behavior, aimed at preserving body energy, is most often seen in small birds, such as hummingbirds and swifts. 

In most cases, however, passerine birds will simply settle down for the night in a hole within a tree, or even in disused nesting boxes. Some species add animal fur or grass to increase insulation.

How Do Passerine Birds Not Fall Out Of Trees When Sleeping?

A Siskin Sleeping
Image by fotobagaluten via Flickr

Well, these little guys don’t get their perching name for nothing. 

When a bird puts any form of weight on its feet, muscles within the leg force tendons within their feet to tighten, forcing the foot to remain closed.

This involuntary behavior creates a vice-like grip on any surface the bird comes into contact with. So, even when sleeping, a bird will remain perched without the risk of falling. 

How Do Migratory Birds Sleep?

Migration is a key evolutionary strategy whereby an animal, or species, leaves one area to travel to another. 

Oftentimes, birds migrate to escape unfavorable weather conditions, such as the extreme cold. 

Twice yearly, many bird species undertake arduous journeys across the globe to reach new environments. 

One of the most famous long-distance migrant is the swift. 

In fact, the alpine swift holds the record for the longest recorded uninterrupted flight by a bird – over 200 days in the air!

Typically, migrating species will stop off in passing countries to recuperate and build up energy reserves. However, ornithologists have speculated that swifts spend much of their life on the wing. 

And, in 2013, this theory was shown to be correct.

Migration Patterns Of The Alpine Swift

A team of researchers studying alpine swifts discovered that they migrate between their breeding grounds in Switzerland, to their wintering grounds in Western Africa. Using tags that log flight information, the researchers found the swifts were airborne for the duration of the trip. 

This behavior is similar to those observed by offshore birds, which spend much of their lives out at sea. 

The researchers identified periods of increased and decreased activity, where low wing flapping was recorded, as well as elongated gliding flights. These changes of activity levels whilst in flight suggested periods of some kind of sleep in flight

However, there are other birds, such as the bar-tailed godwit, that travel exceptional distances without resting. One individual was recorded flying non-stop for over 8,000 miles, over a period of 11 days, between Alaska and Tasmania. 

Only once it has arrived in their desired destination will the bird rest. 

Some migratory birds use thermals, pockets of warm air, to help them glide to save energy. It is thought that whilst soaring on the thermals, some migrant species may squeeze in a few Z’s. 

How Do Waterfowl Sleep? 

Waterfowl includes species such as ducks and geese. 

Like other species of birds, waterfowl display unihemispheric slow-wave sleep (USWS). They can close down half of their brain to sleep, whilst the other half remains awake and alert. 

Rottenburg, the guy who conducted the frigatebird study, also carried out research on mallard ducks

Placed in a row of four, he noticed the two ducks in the middle slept with both eyes shut, whilst the ducks on the ends of the row would sleep with one eye open. 

When rotated, the ducks exhibited the same behavior. 

Using electroencephalogram recordings, it was found that the side of the brain that controlled the eye opening had the activity of an awake bird, whilst the side with the closed eye showed similar characteristics of a duck in sleep. 

Sleeping Mallard Ducks
Image by Stephanie Pluscht via Flickr

Like passerine birds, this is an anti-predator strategy that enables the ducks to get sufficient levels of rest, whilst being prepared to flee in the event of a threat. 

Physical Behaviors of Sleeping Waterfowl

The difference with waterfowl from passerine species is the physicality of sleep. 

Sure, there are some ducks that display similar behavior to passerine species, like perching in trees.

These aptly named perching ducks, stay rooted on trees via sharp claws on their feet.

But most other species of waterfowl sleep differently. 

When seated, be it on dry land or in the water, waterfowl have a tendency to tuck their bill into their feathers, bending their head backwards doing so. 

This is typical of heavier waterfowl, such as muscovy ducks, which rest their head and neck muscles on their bodies, to avoid neck injuries whilst sleeping.

The composition of the feathers between waterfowl and passerine birds are slightly different. Living in or near to water, many waterfowl species have evolved waterproof feathers. Due to the higher oil content to make these waterproof feathers, waterfowl can’t quite as readily fluff up their feathers like passerine species do. 

So, by nestling their head into the feathers, waterfowl are able to effectively conserve body heat. 

However, other theories suggest the placement of the head on their feathers is to better align their ears and eyes to see any approaching ambush predator. 

Final Thoughts 

Birds are exceptional creatures that have adapted to a range of habitat types.

However, many bird species are susceptible to predation. 

Unfortunately, like most animals, birds need to sleep. But there is a trade-off between getting a restful sleep and watching out for predators. 

The solution?

Many bird species, from passerine to waterfowl species, undergo unihemispheric slow-wave sleep. This means they can effectively close one half of their brain down to sleep, whilst the other side, the side connected to an open eye, can stay vigilant. 

A pretty nifty compromise, if you ask me.

Bird Behaviors

Why do Birds Sing? Unravelling Nature’s Secret Symphony

Whether you’re strolling through the garden or exploring the outdoors, you will notice how every bird song sounds a little bit different.

From the croaky caws of the crows, to the wistful-sounding coos of the Mourning Dove and even Common Grackle’s rusty gate-like calls – each bird has its unique symphony. 

Common Grackle Bird Sings
Common Grackle (Quiscalus quiscula). Image by Ed Rizer via Flickr

What motivates birds to ‘sing’?

What is the motivation behind the great natural orchestra of bird song and calls? 

Bird vocalizations are broadly categorized into two types: songs and calls.

Songs are structured and complex vocalizations with melodies that even Mozart could appreciate. The primary reason birds sing is to defend their territory and to attract a mate. For the most part, only the males produce bird songs. There are exceptions to this though, particularly within tropical species, where some female birds sing and even duet with their male counterparts. 

Why some birds don’t sing

In fact, only birds that have a syrinx – a highly developed vocal organ – can sing. 

Unlike the larynx, the human (and mammal) voice box that sits higher up in the throat, the syrinx is located where the windpipe branches to connect the two lungs. This gives it a paired structure which allows some birds to produce more than one sound simulatenously. Imagine being able to sing your two favorite songs at the same time! 

Birds, like New World vultures, lack this singing organ and so can’t make bird songs. Instead, they make throaty hisses and grunts.

Turkey Vulture
Turkey Vulture (Cathartes aura). Image by Mark Heatherington via Flickr

Mastering bird song melodies

Much like how we learn to speak as a child, young birds master the art of singing through listening and copying their parents and other birds. 

Each species passes down their songs from one generation to the next. As a result, bird songs can often have ‘regional dialects’, with one species singing slightly differently from one location to another. 

What’s different about bird ‘calls’?

These are shorter and simpler vocalizations that a bird produces instinctively and does not need to learn externally. Although mainly male birds sing, both females and males produce calls.

Check out this Great Tit showing off a variety of his bird calls on one of our Nest Box Live cams:

As we’ve learnt, bird song usually coincides with mating and territory defending. However, there are various other scenarios when a bird will need to use a call:

Alarm Calls

For example, birds often use an alarm call. This is to warn other birds that a threat, like a sky-borne predator, is approaching. Many bird species have similar alarm calls and so different species can understand and benefit from each other’s calls. 

A common type of call (and one you may have heard if you have seen our nest box live videos!) is a begging call. Young chicks use this to tell their parents ‘feed me!‘.

Barn Swallow Chicks Begging
Barn Swallow (Hirundo rustica) chicks. Image by Dominik Siegmund via Flickr

Attention calls

What we often don’t realize is: the chick’s parents also use a call during feeding. This is a feeding call and it tells the chicks to open their beaks, if they haven’t already.

Lastly, another common bird call is a contact call. Birds use these calls to ‘stay in touch’ and know where each other are.

Take a look at this Eastern Bluebird demonstrating how she uses a contact call, probably directed towards her male mate.

Click here to find out more about the Nesting Behaviors of Eastern Bluebirds.

You’re likely to hear contact calls within flocks of flying birds, for example, groups of ‘honking’ geese.

Despite being shorter and less complex, bird calls can often be as recognisable as a bird’s song. Take the Black-capped Chickadee with its distinguished ‘chickadee-dee-dee’ contact call. 

The importance of listening to bird song

The world of avian communication is intricate and fascinating. Taking the time to listen a little deeper to our feathered friends can tell us not only what bird we are hearing, but what it is trying to say.

So, the next time you find yourself outdoors, take a moment to listen and decode the secrets hidden in the bird songs and calls of our avian companions.

Bird Behaviors

Why Have Birds Disappeared From My Garden This Winter?

Birds are a staple of any UK garden. 

In the summer months, an explosion of life can be seen in and around our gardens and countryside, as hungry months eagerly stock up on food and race to breed. 

Come winter, however, there is a considerable reduction in the number of birds in our gardens. 

Robin in Winter Snow
Image by Tony Nellis Photography via Facebook

But why?

Well, there are various reasons. From natural migrations to spikes in diseases, this article aims to explore why there seems to be fewer birds in our gardens over the winter.

Birds Migrate South For The Winter 

The most obvious reason for the apparent lack of birds is simply because they are no longer around. 

During the summer months, temperatures and environmental conditions are relatively stable. Oftentimes, there is an abundance of food, which can support healthy populations of birds of all species. 

In winter, however, resources are depleted. Temperatures plummet and storms become more prevalent. All of these factors make survival increasingly difficult.

Blue Tit in Winter Snow
Image by Tony Nellis Photography via Facebook

So, how best to avoid poor environmental conditions?

Easy! To leave altogether. 

The process whereby an animal travels from one region to another is referred to as migration. 

There are a variety of different types of bird migrations. However, the most common forms displayed by UK species are:

  • Seasonal Migration – The movement of species between breeding and non-breeding regions. 
  • Latitudinal Migration – The movement of species from North to South, and vice versa. Many UK garden birds disappear in the winter, as they travel South to warmer climates. 

Many bird species that can be found in gardens across the UK in the summer months make arduous journeys in search of warmer climates. 

In temperate regions, such as the UK, it is estimated that at least half of our birds are migrants. This is especially the case for insectivorous birds, which migrate to where insects are more abundant. 

UK Migratory Bird Species

Some of the most famous migratory species found in our gardens are swallows.

Twice yearly, these small, highly aerial birds embark on an impressive 6,000 mile migration between the UK and South Africa. 

Swallows Flock
Image by Keith Simpson via Flickr

During the summer months, swallows gorge themselves on flying insects, such as horseflies and grasshoppers. Come autumn, populations of insect prey dramatically decrease. 

To avoid starvation, these little birds, weighing just 20 grams, travel up to 200 miles per day to reach new foraging grounds. 

But hey, I think I would battle exhaustion and starvation if it means getting out of a British winter. 

A very similar species to swallows, the swifts, also travel thousands of miles every year to escape the peril of British winter’s. 

Departing from the UK between June – August, new data has revealed that swifts can travel between their breeding sites in the UK to their new foraging grounds in Africa in just 5 days. They have been known to stop in countries bordering the Atlantic coast of North Africa. 

However, these highly agile birds aren’t the only ones to leave our gardens. 

Whitethroats, and other warbler species, as well as thrush species, such as wheatears, also take to the sky as winter approaches in the UK, leading to further disappearances in our UK garden birds. 

In October, having spent the summer months breeding in the UK, whitethroats leave our shores and make the treacherous journey to Sahel, just south of the Sahara. 

This dry area is prone to periods of drought which, if for prolonged durations, can affect the overwinter survival of whitethroats. In the late 1960s, a severe drought in the region led to a 90% population crash in the UK population on whitethroats. 

West Africa is a popular winter destination for many UK bird species. Cuckoos, redstarts and turtle doves also leave UK gardens and disappear over the winter period. 

Changes To A Garden Setting

Once overlooked for their small size, and seeming inability to house significant environmental resources, gardens have now been proven to be a vital hotspot for many ecological niches. 

Not only can they offer foraging opportunities for a variety of bird species, gardens can also provide shelter and nesting spaces – especially with the addition of artificial features such as bird feeders and nest boxes. 

Coal Tits on Bird Feeder
Image by Brian Kennedy via Flickr

However, many bird species are highly neophobic. They do not like change and are wary of novel items. 

But, when you’re on the menu for a lot of other species, this is understandable. 

Have you changed the layout of your garden? Added any new features? A new washing line perhaps, or even a garden gnome? 

Even features that would seemingly increase a bird’s survival, such as new feeders, may be the very reason that birds are no longer visiting. 

All it takes is a bit of patience. 

It takes just a couple of brave, or hungry, birds to eventually inspect the new settings. Eager eyes watch and wait, ensuring the coast is clear before joining.

Declining Populations 

There is a final, more sinister reason as to why you may be seeing fewer birds in gardens over winter: population declines. 

There are a range of different factors that influence population declines. Some, such as diseases, can be seasonal. Other factors, such as climate change, are having long-term implications on our garden birds. 

Disease Affects Garden Birds

For humans, the common cold becomes progressively more pronounced in the winter. People remain indoors and within close proximity to one another, allowing the disease to spread like wildfire. 

Well, something similar occurs in birds. 

Avian influenza, or bird flu, is a highly contagious respiratory disease that affects many different bird species. 

However, during the winter months, a more serious strain of avian flu, known as highly pathogenic avian flu (HPAF), has been taking a toll on bird species commonly found in gardens. 

It is thought that migrating waterfowl species, such as ducks and geese, act as carriers for the disease, spreading it to susceptible species, such as reed buntings. 

HPAF spreads from bird to bird via contact with infected salvia, nasal secretions or feces. It can also be transmitted by predation. However, once this aggressive strain of flu makes its way into a population, the damage can be irreversible. 

Bacterial bird infections, such as that of Salmonellosis, is another problem for many garden birds over winter, especially seed-eating birds such as sparrows and finches. 

With natural food resources depleted, different species of garden birds may congregate in one centralized location, such as a bird feeder, where food resources are still plentiful. With such a high volume of birds in one area, droppings will inevitably accumulate. 

Bird feces, infected with the Salmonella bacteria, contaminate food items, which are then ingested by other hungry birds looking for an easy meal. This is referred to as faeco-oral transmission. 

The combination of viral and bacterial, as well as parasitic, infections over the wintering period can cause serious population declines to our garden birds. 

In the last 11 years, populations of chaffinches have fallen by 30%, whilst populations of greenfinches have decreased by 67%. Both of these declines are attributed to disease outbreaks.     

Habitat Loss 

When we talk about habitat loss, it is easy to think of the industrial deforestation occurring in our tropical rainforests. 

Chaffinch on Ground
Image by Tony Nellis Photography via Facebook

Now, while this is a serious global issue, habitat loss occurs all across the globe. Habitat loss is the destruction of any habitat which supports native species and is more broad than just the loss of trees. 

Swifts, swallows and house martins, for example, often nest in old buildings close to a water source. 

For successful nests, it’s all about location, location, location. The nest itself has to be easily accessible, and free of obstructions such as branches. Typically, nest sites for these species are under eaves of old houses. 

However, many old properties are being redeveloped or torn down altogether to make way for new developments, leaving no suitable nesting sites for these small birds. 

Many new homes are seeing the switch from natural to artificial lawns. This blatant destruction of habitat destroys natural foraging grounds, removes nesting material and increases competition for suitable nesting sites. 

If you absolutely have to use artificial grass, and I strongly suggest you reconsider, try adding natural borders of native flowers, bird feeders, insect houses and nest boxes, and leaving any larger trees. 

Climate Change 

Climate change has been negatively affecting wildlife populations throughout the world. 

However, some of our resident UK garden birds may have actually benefited from a changing climate. Some species, such as the nuthatch, have colonized new, northern areas which were historically too cold for the small bird. And, as a response, have disappeared from gardens further south. 

Nuthatch on Tree
Image by B.Dawson Photography via Facebook

But, whilst some birds seem to be better off, impacts on other bird species, especially migratory birds, have been far more dire. 

Long-distance migrants, such as swallows and whitethroats, do not benefit from the warmer winter temperatures. These species are also affected by weather conditions in their African wintering grounds. 

As the climate in these parts of the world increases, we’re experiencing more severe droughts, intense storms and frequent wildfires. All these factors are destroying natural bird habitats at a faster rate than usual. 

As a result, UK breeding populations of winter migrants fluctuate in relation to weather conditions in Africa. 

Migration Problems 

As a response to climate change, investment into the green energy sector has seen an enormous boost. 

Short Eared Own with Wind Turbine
Image by Les Lawrence via Instagram

One of the most endorsed green energy schemes, wind farms, seem like a great idea to provide an alternative to fossil fuels. 

And, whilst they are, offshore wind farms are having negative impacts on migratory bird species.

As migratory birds travel across open oceans between Africa and the UK, the risk of collisions with turbine blades is increased, affecting overall populations of birds, further decreasing populations seen in gardens. 

Final Thoughts 

Bird populations in our gardens fluctuate seasonally. 

During the summer months, a bountiful supply of food and stable environmental conditions sees a large bird diversity visit our gardens. 

However, when conditions become less favorable, almost half of our bird species migrate southwards, vacating our gardens for the winter period. 

Unfortunately, climate change is affecting migrating birds; both in the UK and wintering countries, such as Africa. Climate mitigating strategies, such as wind turbines, are also negatively affecting migrating birds through collisions. 

Want to make a difference? Try a bit of citizen science this winter period and record the bird species you see in your garden. Submit findings to the RSPB to help scientists track bird numbers.

Bird Behaviors

American Tree Swallow Breeding Behaviors

In early spring, just as the sun starts to warm the land and green sprouts poke through the cold earth, American Tree Swallows migrate north from wintering in the south. Flying many miles during the day, they migrate to northern North America in search of breeding grounds.

Tree Swallow breeding commonly takes place in man-made bird boxes, making them an easy bird to attract to your garden. In fact, this species greatly benefits from bird boxes, as they have to compete with other cavity-nesting birds, such as house sparrows, bluebirds, and woodpeckers.

Tree Swallow in Nest Box
Image by Elm Street Photography via Facebook / Website

The Tree Swallow is a stunningly beautiful bird, as their shining blue-green feathers and crisp white chests are unlike any other, making them a wonderful bird to witness in a bird box. But before we dive into the specific nesting habits of this special bird, let’s get acquainted with who this bird is, including its description and characteristics. That way, you can confidently identify it as a Tree Swallow if you have one visit your bird box.

How to Identify a Tree Swallow

Tree Swallows (Tachycineta bicolor) are a small bird in the swallow or Hirundinidae family. They are characterized by their stunning, iridescent blue-green feathers and their particular swooping and diving flight patterns.

Tree Swallow with Juvenile
Image by Heather Rose Assal ©

They are acrobats of the sky, flying gracefully in astounding displays of steep dives and quick turns to catch their unsuspecting prey, which consists mostly of flying insects. Because of this, they prefer open areas near water, such as meadows, rivers, marshes, and lakes, which attract breeding insects.

Their species name, bicolor, denotes the dark blue-green feathers on their back and white feathers below. They can look slightly similar to Barn Swallows (Hirundo rustica) but are easily distinguished by their chest colors; Tree Swallows have clean white chests and bellies, while Barn Swallows have a more rustic brown color, hence their species name.

Tree Swallow Breeding Habits

Tree Swallows breed throughout most of Canada (up to tree line) and in parts of the United States. Their breeding range in the western United States typically extends from northern California over to Colorado and up to Alaska. They also breed in the upper midwest from North Dakota to Michigan and throughout the Northeast, down to Pennsylvania. It is uncommon for them to breed in the central midwest and southern United States, preferring somewhat cooler climates to raise their young. 

Image by Elm Street Photography via Facebook / Website

Breeding occurs between May and September, and they have one brood per year. Males usually arrive at the breeding area before the females to search out potential nest sites.

As cavity nesters, the male looks for natural cavities in standing dead trees or abandoned Woodpecker nests. They will often nest in man-made bird boxes, building eaves, or even holes in the ground (probably as a last resort if there are no cavities available). Nests are usually chosen in areas near water or open meadows where there is plenty of food to feed the chicks.

Part of their courtship involves the male Tree Swallow showing the female various nesting sites. He will do this by perching near the nest holes or on top of the bird box. He will do flutter flights and bowing displays in front of the female, hoping to impress her with his charm and nest-finding skills.

Typically, one male mates with one female, though they don’t mate for life and will choose new partners each year. Plus, Tree Swallows aren’t always monogamous, and one male may mate with two females, or a female might mate with another male. It is not uncommon for chicks in a single nest to have different fathers.

While they fly in large groups when migrating, Tree Swallows disperse to find their breeding partners and aggressively defend their territory once a nest is selected.

How do Tree Swallows Build Their Nests?

Once the playful courtships have ended and nest sites have been chosen, the female builds the nest with dead grass, moss, rootlets, and other small, fibrous materials. She begins her work with the outer circumference of the nest and uses her feathers to push out the material to shape it into a cup.

The female tree swallow does this repeatedly; as she adds new material, she pushes it out with her wings so that there is an indented cup area for her to lay her eggs. The last layer of the nest is lined with soft feathers. Nest building can take anywhere from a few days to over two weeks.

Once the first layer of feathers is laid, the female will lay her first egg. She lays one egg per day and will lay about 2-8 eggs (5 is average). The eggs are pale pink at first and then turn to pure white within the first few days of being laid. The male and female continue adding feathers to the nest after the female lays the eggs.

Incubation and Nestling

The female Tree Swallow incubates the eggs for about 11-20 days. It is common for the female to periodically leave the nest – sometimes for several hours on warm days. All the eggs hatch within a couple of days, and the mother will take the eggshells out of the nest as the chicks hatch.

Image by Nest Box Live

Both the male and female feed the hatchlings. The chicks are born helpless with closed eyes and pink skin sparsely covered in downy feathers. For the first few days after they hatch, the female broods them to keep them warm. As the hatchlings mature, the chicks’ downy fuzz thickens into dark black-brown feathers, and the mother starts to spend less and less time with them.

The hatchlings stay in the nest for about 15-25 days, miraculously growing into fledglings able to take their first flight upon leaving the nest. They leave the nest one at a time, with all the fledglings leaving within one to two days.

Image by Nest Box Live

After they leave the nest, both parents will continue to feed the fledglings for a few days. Because they mature quickly, the fledglings will reach adulthood and breed by the following spring.

Watch the full video of the Tree Swallow breeding cycle on Facebook.

How To Encourage Tree Swallow Breeding In Your Garden?

It’s one thing to learn about the fascinating nesting habits of tree swallows, but it’s another thing to see it firsthand – in real time!

With our Nest Box Live – AI-Powered Bird Box, you get the unique and incredible opportunity to witness birds choosing your bird box, building their nest, laying eggs, and raising their young.

While you can’t be certain what species of bird will choose your bird box, chances are high it may be a tree swallow if you live near its ideal breeding habitat. If so, you’ll have a wondrous opportunity to see what was described here in action and become intimately familiar with the spectacular Tree Swallow.

Bird Behaviors

Nesting Behaviors of Eastern Bluebirds in the USA

Found in North America, there are three known species of bluebird; the Eastern 

Bluebird, the Western Bluebird and the Mountain Bluebird. 

Living up to their name, bluebirds are, well, blue. 

Bluebird Bird Box Top
Image by Lydia Lively©

However, it is not just their striking colouration that makes the bluebird stand out. It is also their interesting approach to nesting. 

Being secondary cavity-nesting birds, they rely on other species to create spaces for them to nest. Once in the vacant cavity, each sex has a defined nesting behavior. Female Eastern Bluebirds build and contrast the nest, whilst the male guards his mate.

This article will aim to explore the nesting behaviors of the Eastern Bluebirds.

What Are Eastern Bluebirds?

Before we delve into the world of Eastern Bluebird nesting, first we need to understand what exactly an Eastern Bluebird is. 

The Eastern bluebird is a small passerine bird species belonging to the thrush family, not too dissimilar from the European robin.

Although the Eastern Bluebird has a strikingly vibrant blue head and wings, their breast is a mix of orange and white plumage.

Bluebird Solo
Image by Drunken Birder© via Instagram

These colors become even more pronounced in males during the breeding season, which occurs throughout the Spring and Summer months – typically between April to July. 

Fractionally larger than their Western cousins, the aptly named Western Bluebird, Eastern Bluebirds can reach lengths of 21 cm and weigh up to 32g. They are omnivorous foragers, feeding on a range of insects and seeds and berries. 

Eastern Bluebirds are a highly social bird species, often observed flocking together in groups of over 100. 

Geographical Distribution of Eastern Bluebirds

Eastern bluebirds have a relatively large range and, as the name suggests, can be found in much of Eastern North America. They typically occur East of the Rocky Mountain range.

There are 8 recognised subspecies of the eastern bluebird. Some can be found as far North as South Canada. Other populations can be found as far South as Nicaragua. 

Eastern Bluebirds living in warmer regions, such as Southwest USA and Central America, will remain year-round. 

Other populations, especially those living in Canada and North USA, are partial migrants. 

This means, during certain unfavorable months, individuals migrate from their breeding sites to new areas with plentiful food and a stable climate. 

Eastern Bluebirds are heavily dependent on weather and the climate. If conditions are too cold, many individuals will perish. 

To avoid high chick fatality rates, adult Bluebirds nest in enclosed cavities within trees. Not only does this protect developing eggs and chicks from potential predators, it also provides the young some respite from the elements. 

Where Do Eastern Bluebirds Nest?

Bluebirds are secondary cavity-nesting birds. 

Despite its long-winded, and somewhat complicated, name, secondary cavity-nesting birds really do what they say. Let’s break it down. 

The “cavity-nesting” aspect is derived from where they nest. For Eastern Bluebirds, which are susceptible to cold weather and high predation risks, holes within trees, or cavities, offer increased protection.

However, Eastern Bluebirds lack the necessary adaptations that would allow them to create these cavities themselves – their beaks and feet simply aren’t strong enough to pick away at tree bark. 

Instead, they must rely on other species to construct these initial cavities. Such species, such as woodpeckers, are referred to as primary cavity-nesting birds. These are the species that make the original holes. Fortunately for the Bluebirds, woodpeckers typically use their cavities for just one season, before moving on to create a new hole. 

Vacant holes are prime real estate, and they are free for the taking. So, can you see where the “secondary” aspect comes from?

However, the best sites come at a cost. Before the breeding season, males will compete with one another to gain the best nesting cavity. 

Although Bluebirds can be found across much of North America, they are found in particularly high densities throughout human-modified environments, such as pastures and agricultural land, orchards, parks and gardens.

Typically, when humans alter wild landscapes, it is to the detriment of the species living there. 

For the eastern Bluebird, however, human modification has allowed populations to flourish. Rotting fence posts provide an excellent place to bore. Fruit orchards contain stable food sources. Suburban parks and backyards may have artificial nesting boxes. 

All these factors have allowed the eastern Bluebird to nest successfully in an ever-changing world. But more on that later. 

Copulation In Eastern Bluebirds 

Copulation, otherwise known as sexual intercourse, is the process of transferring sperm from the male, to the eggs of the female. 

This is an incredibly energetically costly investment for the female, so she needs to make an informed decision before mating with just any old mate. 

And the male knows this. 

Bluebird Pair
Image by Drunken Birder© via Instagram

So, in order for the male to secure mating rights with the female, he must impress her. 

Not only does he do this with his brightly coloured plumage (the brighter the feathers, the healthier the male), but also by his erratic displays. 

After selecting a nesting cavity – be it an old woodpecker hole, a rotting fence post, or an artificial nest box – the male Eastern Bluebird sings in front of a potential mate.

If the female is interested, the male will begin bringing nest material to the cavity. Entering in and out of the hole, the male will partially spread his wing and tail feathers. 

If he is successful, the female will initiate copulation. Both facing the same direction, the male Eastern Bluebird will mount the female’s back, attempting to make cloacal contact. This is typically done from a perch, close to the nest cavity. 

The cloaca, present in both males and females, mostly in birds, reptiles and amphibians, is a dual-functioning opening for the digestive, reproductive and urinary tracts. Talk about efficiency. 

In mere seconds, copulation is complete. In most bird species, courtship behaviors often last significantly longer than the main event. 

Now, preparations for nesting can begin. 

Does Sex Affect Nesting Behavior?

Sex plays a significant role in the nesting behaviors of Eastern Bluebirds. 

Most Eastern Bluebirds are monogamous or, in other words, they have just one mate. 

However, this monogamous behavior seems to vary. 

Some eastern Bluebirds show signs of lifelong monogamy, where mates form strong bonds with one another for the duration of their lives. 

Other individuals display seasonal monogamy, whereby partners will mate for the duration of the breeding season, then proceed to find other mates. 

Image by Drunken Birder© via Instagram

Regardless of the type of monogamy displayed, one would expect an equal relationship when it comes to nest building. 

However, in the case of the Eastern Bluebird, it is the females that do most of the work. 

Over the duration of around 10 days, the female lines the cavity with a variety of materials – most of which consists of grass – that is loosely woven together. Some individuals take nest building one step further by adding good insulating materials, such as horse hair or feathers. 

Although he has no input in the construction of the nest, the male remains close by. Ever vigilant, the male guards his mate, warding off any predators or potential male competition. 

Once the female has constructed her nest, she will lay up to 7 teal-colored eggs. She will incubate the eggs for around 2 weeks, and then an additional week after her chicks have hatched. During this nesting period. The female will rely on her male partner to bring her food. 

Like many bird species, baby Eastern bluebirds are altricial. They are born blind and featherless, and must rely on their parents until they become nutritionally independent.

Older Sibling Nesting Behaviors 

The world can be a scary place, especially for an Eastern Bluebird. 

For some individuals, it pays to stay close to the nest. This is especially true of those who hatch towards the end of the hatching season. 

Once fledged, these juveniles may stay in the territory of their parents. 

Occasionally, these young birds may help their parents raise the brood of the following season. 

But why? 

Image by Heather Rose Assal ©

Well, it is speculated that the young birds stick around for selfish behaviors. They feed their siblings to gain knowledge on nesting behaviors that may inadvertently increase their own nesting successes when they breed. 

This behavior is defined as alloparental care, whereby care is given to non-descendent young. 

Although there are some costs for the caregivers, such as delayed personal reproduction, the benefits outweigh these costs. Chicks have a higher likelihood of survival with the additional support, and the caregivers receive knowledge that will increase their chances of a successful brood. 

Another theory suggests that, by helping to raise sibling chicks, it ensures at least some of the genes of the helper are passed on. 

How Humans Can Help

By the turn of the 20th century, Eastern Bluebird populations had plummeted by nearly 90%.

Owing to habitat loss, competition with introduced species, pesticide use, and climate change, just 18,500 bluebirds were recorded. 

However, in a remarkable display of human cooperativity, artificial nest boxes were erected nationwide. 

Juvenile Bluebird Bird Box
Image by Drunken Birder© via Instagram

With the additional space, Eastern Bluebirds were able to recognize areas once deemed unsuitable due to habitat loss. 

These new nesting boxes were designed with the size of the eastern Bluebird in mind. The entrance hole was big enough for the Bluebird, but too small for the introduced and invasive starling, eliminating interspecific competition for nesting sites. 

Today, the Eastern Bluebird is one of the most numerous bird species in North America, with populations estimated to be close to 23 million individuals. A truce conservation success story. 

Final Thoughts

In today’s modern world, conservation success stories are few and far between. 

With a range of threats facing the natural world, it is hard for wildlife to thrive. 

However, with the help of humans, Eastern Bluebirds are thriving. 

Owing to the installation of nest boxes, these secondary-cavity nesters were able to successfully raise chicks without the risk of competition, habitat loss and extreme weather. 

Juvenile Bluebirds
Image by Drunken Birder© via Instagram