It’s always exciting to watch a bird fly into their secret little spot in the bushes and know there’s a nest with bird eggs hidden inside.
On my own journey to get connected with nature, some of my biggest discoveries and lessons have come from time spent watching nesting birds in action.
Bird nesting behavior is pretty easy to observe so this is a great place for beginners to explore… but there are also some tricky spots where people get stuck.
One of the most common questions is how to determine – when do birds lay eggs?
Most birds lay eggs anywhere from early spring until mid-summer, however the exact timing varies depending on how far north you are, and the particular species of bird you’re watching.
Some birds will even lay multiple sets of eggs, which is why you might continue seeing birds nesting well into summer.
On the surface it would seem like the exact timing of egg laying should be pretty straightforward, but there’s actually so many subtle factors that it’s worthwhile breaking this down into more detail.
The more precise you can get about knowing when exactly birds are laying eggs, the easier it is to track and monitor their complete life-cycle, as well as to understand their alarm language during nest robbing.
The best results come from using a holistic perspective, taking into consideration the complete ecology, location, weather, nest predators, and local behaviors.
So in this article I want to take you on a deep dive into the dynamics surrounding bird nesting activity so you can watch & observe how it all works in your area.
Our goal is to help you become an absolute whiz at knowing when birds are laying eggs in your area. Let’s explore this in more detail!
Bird Nesting Stages & Behavior
The most effective way to confidently identify when birds are getting ready to lay eggs in your area is by observing their mating & nesting behaviors.
We can break the entire nesting process into 6 behavioral stages that help you identify when you’re close to egg-laying time.
Here’s what to look for:
Stage 1: Courtship & Pairing
In this first stage, birds are just beginning to prepare for nesting.
Most likely you’re just coming out of winter and the food abundance is rapidly increasing, along with things like daylight and temperature.
Behaviorally, you’ll notice birds begin to break out of their winter flocks and become anchored to a much smaller core territory.
This will eventually be their nesting territory.
Males will then start singing and chasing other males out of their territory.
Songs are being made to attract females, and also protect territory from rivals.
Soon the females will begin choosing which partners they want to pair up with.
Look for birds singing, pairing up & protecting territory from other members of their own species. You might also see little gestures of romance like males feeding females.
These are all signs you are currently in stage 1 of the nesting season.
Stage 2: Nest Building
Soon after the birds have paired up, they will then choose a spot to begin building their nest.
Sometimes both the male & female build the nest together, and other times it’s just the female.
The main thing to watch for here is birds carrying little twigs or gathering mud, or simply flying into certain sheltered spots repeatedly.
It’s important to give the birds space and try not to give away their nest location to nest robbers like jays or crows.
This is a good time of year to settle into a sit spot and watch from a distance for any patterns of movement.
Here’s an old video I created that explains some simple distance techniques to help you locate bird nests:
Watch carefully over the coming days and weeks because the birds are now getting very close to mating & egg laying time.
Stage 3: Mating
After the nest is built, this is when mating occurs.
The females need their eggs to be fertilized by their partner before they can be laid in the nest.
It’s also a very energy intensive process to lay eggs, so the actual mating & egg laying typically occurs over a period of several days.
Mating birds can be tricky to observe, but if you spend enough time quietly watching you will definitely catch it.
I usually see birds mating in the morning hours, and it might only go on for a few days or a week before all the eggs are in the nest.
It’s quite a subtle behavior but this is exactly when the eggs are being laid… during this stage 3, just before moving into stage 4.
Look for signs that the birds have finished building their nest. You might notice this more as an absence of nest building that would have been present in days leading up.
Also look for actual mating activities in the branches of trees. The male & female might perch close together, intermittently chasing.
Stage 4: Incubation
During incubation the parents are now sitting on the nest keeping the eggs at the right temperature.
They have to continue feeding themselves and staying nourished, while evading predators.
If you notice nest robbers in the area at this time, sometimes the parents will get scared off the nest, or fly out to alarm at some invading crows. If you watch carefully they will return to the nest as soon as possible.
If the eggs get too cold, or a nest robber identifies the nest location, the parents can lose their family and might need to start over again.
Watch for birds being very closely anchored to their nest, and sitting on the eggs.
Stage 5: Hatching & Nestlings
With enough patience and a bit of luck, the eggs will hatch and move into their nestling phase.
You’ll recognize this stage by seeing the parent birds flying back and forth to the nest with food for their young.
The babies might beg with a quiet cheep! cheep! cheep! sound whenever the parents approach the nest.
This nestling phase will typically last a few weeks, or sometimes longer in large bird species.
Stage 6: Juvenile Fledglings
After a few weeks, the nestlings are ready to test out their wings. At this stage they look pretty much like full sized birds, but their awareness is undeveloped.
Their flying abilities are not very good, and they’re still completely dependant on their parents.
You’ll notice juveniles fluttering their wings and following their exhausted parents around begging for food.
Behavioral Tracking With Nest Stages
The key thing to realize with these 6 stages is that bird nesting can be tracked behaviorally in stages.
There are certainly general rules about when birds lay eggs in any particular part of the world, but the actual dates can change from year to year depending on things like temperature & local conditions.
So the only way to know for sure when birds are laying eggs is by observing their behavior very closely and looking for these nesting stages.
Simply remember that birds lay their eggs at the transition point between stage 3 & stage 4.
14 More Factors That Affect Nesting Behaviors
The 6 stages of bird nesting behavior apply to all birds, however the particular mating patterns can also vary quite a bit depending on the individual bird species.
The exact timing can shift quite a lot too according to local conditions.
While we typically associate bird eggs with the coming of spring, sometimes birds will lay eggs during other times of the year, or with unexpected timing & behavior patterns.
It all depends on things like:
- Where you’re located
- Nesting strategy
- How much food is available
- Day length
- Laying Intervals
The more awareness you have to track these more subtle nesting influences in your own local area, the easier it will be to spot the early signs of nesting.
So here are 14 more things to consider as you start tracking the bird nesting stages in your local area.
1. Life Partners VS Promiscuous Birds
Some birds mate for life, while others may have multiple mates. Whether a bird mates for life or finds multiple mates will depend on the species of bird.
Birds who mate for life tend to have smaller families and more extravagant mating rituals. While birds who have multiple mates tend to have larger families and shorter mating rituals.
Birds who mate for life can find other mates if their partner dies. These birds go through a grieving process that is dependent on the sex and species of the bird.
This can all affect the precise timing of nesting & egg laying, even causing some birds to not mate in a particular year.
2. Parenting Strategy
Another thing that sometimes varies quite a bit between species is how the parents divide up the parenting duties.
Some birds like Bald Eagles or Atlantic Puffins share their parenting duties equally.
The male & female both take turns incubating the eggs as well as feeding the young. They also teach their young how to fly, hunt and clean their feathers or wings.
For other species of birds like hummingbirds, all duties fall on the female while the males only focus on reproducing.
These factors all affect the types of patterns you’ll observe while watching for the 6 nesting stages.
Care needed for the young can also change mating & parenting behaviors. Some bird species simply need more care and teachings from their parents than others.
Some birds, like the American Robin, can leave the nest as early as 10 days after hatching. Others like Swans, may take up to 3-4 months to mature.
3. Choosing The Nest Location
Usually female birds have the say in where the nest or burrow will be for their eggs.
However some bird parents, like Bald Eagles or California Condors, look for the optimal location for their nests together.
Female birds like Hummingbirds or American Robins will look for and create their nests alone.
This is useful to know during stage 1 and 2 because it will affect who you should be watching for signs of nesting, and sometimes makes their behavior more subtle.
4. Nest Building Strategy
Actually creating the nest can also be a solo or duel process depending on the bird species. This will have a significant effect on how you identify the early stages of nesting.
Similar to the point above, Hummingbirds and Robins make their nests alone.
Other birds, like Cardinals or Black Vultures, work as a team to create their nests and burrows.
These behaviors are all simply differences between species and do not change the likelihood of their young’s successful hatching.
The important thing is to watch for differences you can observe between males & females because this will help your observations to be more precise.
5. Unsuccessful Clutches
A clutch of eggs is a group of eggs produced by birds at one time that are laid in a nest.
However just because you see birds mating and laying eggs, doesn’t guarantee it will be a successful clutch.
Some of the main factors that affect nest success are:
- Laying interval
- The health of the eggs
These are significant factors in the life of birds and can sometimes dramatically change the specific dates that eggs are being laid in your area.
Last spring I witnessed a pair of robins that had to restart their nest no less than 5 times before they finally were able to start their family.
This is why sometimes you’ll see a pair of birds already feeding juveniles, while another pair is still building their nest.
6. Nest Predators
You simply cannot study the behavior of nesting birds without also studying nest robbers.
In some locations, nest predators can have a significant influence on whether or not birds are successful with nesting.
A few examples of common Nest Robbers are:
- Corvids (Crows, Jays, Magpies)
- Hawks & Eagles
- Squirrels & rats
Predators who commonly eat bird eggs can eat an entire clutch of eggs, thus forcing the female bird to lay a replacement clutch elsewhere.
Some predators can also eat the female, thus killing the eggs since the mother cannot protect them from the heat or other predators.
In the case of birds who get their nests predated by nest robbers like crows, squirrels or raccoons, there’s no choice but to continue building nests and laying eggs many times before they finally achieve success.
7. Nest Parasites
Some birds, rather than building their own nests are known as “nest parasites”.
The brown headed cowbird is a good example of classic nest parasite behavior.
The female will search for nesting females of another species, and quickly lay her own eggs in with the original nest.
Then when the eggs hatch the parasite is able to push out the host’s eggs or compete for food being brought. Thus, killing off the clutch the host bird had laid.
Sometimes temperature swings can affect the success of a clutch.
Yearly variations in temperature can affect how much work is required to maintain the correct egg temperature, causing egg laying to happen early or later.
Birds try to keep the perfect balance by shielding the eggs or providing warmth from body heat. But sometimes during extreme temperature conditions, the health of the eggs can be affected.
Extreme temperatures can also affect things like food availability and mating readiness in birds.
The warmth & moisture of spring will aid flowers and plants to bloom, thus calling on insects and fruits to grow as birds food sources.
Warmth can also prompt earlier mating seasons and there is research showing birds mating sooner in the year if it was warmer sooner than usual.
9. Egg Health
The overall health of the eggs is another factor that significantly impacts the wellbeing of a clutch of eggs.
Not all eggs are born healthy. Some may be diseased, or the fledgling dies during development.
If the disease is contagious, it can also spread to the other eggs and kill them off.
Or, a female bird may realize one egg is dead or diseased and give up on the entire group. Thus leaving the healthy eggs to die as well.
Another common issue with egg health is the effect of chemicals used in agriculture or other applications.
This was a common issue that led to the banning of DDT insecticides which thins bird egg shells, causing massive death rates in birds.
10. Laying Intervals
A laying interval is the length of time between when birds begin nesting and when the young are independant.
It represents the window of opportunity a particular species of bird has to lay eggs during their nesting season.
Some birds are simply capable of developing much more quickly than others, or can withstanding a greater degree of stress during development, leading to longer laying intervals.
Birds with longer laying intervals are more likely to have multiple clutches.
Pigeons and Doves are examples of birds that are capable of laying all year round in some cases.
It’s not uncommon for these birds to lay multiple clutches given that they have ample time to do so.
Other birds who only have a few months lay significantly fewer clutches in comparison.
11. Multiple Clutches
As mentioned in the previous section, some birds may only lay one clutch during their entire laying interval, while others can lay many.
There can be different reasons for this, and some of them are:
- Multiple Mates
- Longer laying intervals
- Replacement clutches
Whenever you observe birds laying multiple clutches, it can be very informative to ask yourself: Why is this happening?
When you look for the underlying reason, it helps you learn more about an individual bird’s response to different types of stress or opportunity.
For example: Is it because these birds recently lost an earlier clutch? Was it the result of a predator? Has the temperature been unseasonably cold lately?
Or is it because their previous clutch was wildly successful and the young have already fledged into adulthood? What does all this tell you about the individual species you’re watching?
These types of questions will help you continual drive your understanding deeper and make sense of subtle patterns that typically go unnoticed.
12. Location & Local Conditions
Location can significantly affect how many clutches a bird can successfully lay in a year.
The amount of food & nesting resources changes significantly depending on altitude, bringing areas of greater or lesser opportunity.
Birds living in lower temperatures will tend to have more unsuccessful clutches due to the high death rate in comparison to birds in warmer climates that have lower rates.
The higher death rate means more replacement clutches are laid.
The location in the world can have a definite effect on what time of year birds lay eggs.
Birds who live in southern latitudes have a longer mating window than those who live at higher latitudes.
In favourable environments you might find birds laying more eggs, and a greater likelihood of multiple successful clutches.
There are also birds like Bald Eagles, that start mating in early January and can lay eggs before Spring officially comes.
13. Food Availability
The amount of food available has an affect on bird mating cycles.
Birds will wait until enough food sources are available before seeking a mate.
They have to sustain themselves for the energy and time it will take to mate, as well as keep their mate and babies well fed.
This might seem obvious, but sometimes there are dramatic differences in food availability during different seasons, even in the same location from year to year.
When food availability begins to rise in early spring, look for an increase of courtship activities.
If you live in warm climate with food abundance year round, pay attention to how this affects the nesting times of different species.
14. Day Length
Even something as simple as day-length can affect how long of a window birds have to mate.
Birds that have more daylength have a longer window of time each day to find food, mate and build their nests for the eggs.
Day length also affects the hormones within birds that promote mating.
Pay attention to this when you’re watching for signs of song, territorial behavior, courtship, nesting & mating.
It all provides useful context for your observations.
As you can see, there’s a pretty incredible variety of factors that influence when birds lay their eggs.
Having awareness of how bird nesting works in your local area simply requires that you take a holistic approach to exploring nature.
If you want to know when birds are laying their eggs, it’s not enough to just casually watch and guess about what they’re doing.
We need to also study things like weather, ecology conditions, predators, species differences, daily & weekly behavioral changes, and so much more!
Start by asking yourself some basic questions like:
- Where am I located? Is this a harsh cold climate? Or a more forgiving warm climate?
- What has the weather been like? If you experience a sudden cold snap, watch for how this affects the behavior of birds.
- Have you been hearing birds singing? Singing is a good sign that courtship is beginning
- Are you seeing birds pair up? Or are they still in large winter flocks?
- Are you seeing signs of nest building?
There’s a lot that goes into egg-laying, so make sure to appreciate the process the next time you come across an active bird nest!