Quick Answers
Most mother birds do not leave their eggs unattended for long periods of time once incubation has started. However, there are some instances where a mother bird may briefly leave the nest such as to find food, escape predators, or defend her territory. She usually returns quickly to continue incubating. Some species may leave for slightly longer to find food during the day. Overall, mother birds are very dedicated to incubating their eggs and minimizing time off the nest until the chicks have hatched.
Birds go through an incredible process to reproduce. The mother lays eggs, incubates them for a specified period of time, and then cares for the hatchlings once they emerge. Since birds are not able to regulate the temperature of their eggs internally like mammals, they must rely on external sources of heat. This makes proper incubation essential for normal embryonic development. As such, female birds are evolutionarily driven to prioritize sitting on their eggs to provide warmth. This has led many people to wonder – do mother birds ever leave their eggs unattended?
Why Do Birds Sit on Their Eggs?
Incubation serves multiple important purposes for bird eggs:
Provides Heat
Bird eggs must be kept at a suitable temperature for normal growth and survival of the embryo. Optimal incubation temperatures vary by species, but tend to range from about 75-100°F. The mother bird transfers her body heat to the eggs by sitting on the nest. If eggs drop below the ideal temperature range for that species, it can put the developing embryos at risk.
Protects Against Predators
A mother bird continuously covering the eggs helps camouflage and shield them from potential predators. If she leaves the nest exposed for too long, it increases the chance of eggs being eaten, destroyed, or stolen by other animals.
Prevents Eggs From Rolling
Bird eggs have rounded or pointed ends, which can cause them to roll around. If an egg shifts too much or falls out of the nest, it could crack, break, overheat, or cool down too much. The adult bird sitting in the nest helps hold the eggs safely in place.
Allows Embryo to Get in Hatching Position
As the embryo develops inside the egg, it needs to orient itself properly to start hatching out. The mother bird’s movements and repositioning while incubating may help facilitate this process.
So in nearly all cases, female birds try to remain on their eggs full-time once incubation starts. But there are some circumstances where they may take a brief recess.
Reasons a Mother Bird May Temporarily Leave the Nest
Here are some common reasons a mother bird may temporarily leave her eggs:
To Find Food and Water
The mother bird needs to keep her own strength up during the incubation period. So she may take occasional breaks to go find food and replenish herself. However, most species try to limit these recesses as much as possible. She usually returns within minutes to resume warming the eggs.
Some adaptations mother birds may have to minimize breaks include:
- Storing up extra energy reserves before incubation starts
- Having the male bird bring food to her in the nest
- Nesting close to sources of food and water
Escape a Predator
If a predator approaches or startles the mother bird, she may quickly fly off to draw it away from the nest. This is an instinctive response to protect herself and the eggs. She will return promptly once the threat is gone.
Defend Her Territory
Mother birds can be quite territorial and aggressive around their nests. If another bird encroaches on her area, she may briefly leave the eggs unattended to chase the intruder away.
Strengthen Social Bonds
Some species have adapted a strategy called synchronous incubation. Birds in a colony will take turns incubating each other’s eggs. This gives the mothers needed breaks to feed and socialize. Even so, no one bird is off her nest for too long before switching back.
Adjust the Eggs
The mother bird may briefly get up, shift around, and reposition the eggs. This ensures they get evenly warmed and develop properly. She likely won’t go far during these short recesses.
Defecate
Mother birds will eventually need to leave the nest to poop. But she won’t go far and will return as quickly as possible. Some birds are so dedicated they even try to hold in their waste while incubating.
So in general, natural selection has favored birds that return to their eggs swiftly after any necessary breaks. Abandoning the eggs for too long would lower the chance of their offspring surviving. Next we’ll look at how long various birds are comfortable leaving eggs alone.
Incubation Attentiveness by Species
The percentage of time a mother bird spends incubating her eggs during the day is called her incubation attentiveness. This varies by species depending on factors like:
- The climate they live in
- Chance of egg predators
- Male participation in incubation
- Ability to store energy reserves
Let’s look at incubation attentiveness for a few example species:
Emperor Penguins – 100%
Emperor penguins breed in the extreme cold of Antarctica during winter. The male does the incubation and is unable to leave at all for over 2 months! He withstands the relentless conditions without food by living off stored fat reserves. Leaving the egg exposed here would mean certain death for the embryo.
Albatrosses – 80-90%
Albatrosses have a protracted incubation period of over 2 months. Both parents participate, with shifts averaging around 3 weeks. Despite needing to fly far out to sea to hunt, they minimize recesses off the nest. Being exposed too long to the elements would jeopardize the egg.
Bald Eagles – 99-100%
Bald eagles demonstrate near continuous attendance on their nest. The egg would be vulnerable to extreme cold if left alone for long in their northern habitats. Both parents play a role, allowing brief breaks for hunting and self-maintenance. Their large nest size also helps insulate the egg.
Cassin’s Auklets – 74%
These small seabirds have an incubation period of about 5 weeks. Parents share duties, with shifts lasting half a day. Their lower attentiveness is attributed to the ease of getting food from nearby ocean waters compared to landlocked birds. But they still minimize recess time to protect the egg.
Orange-cheeked Waxbills – 42%
In contrast to the previous examples, these African finches demonstrate significant daytime recesses. The tropical climate is more permissive for eggs to be left unattended. Both parents help gather insects to feed the hatchlings, necessitating longer off-bouts. However, attentiveness increases to nearly 90% in the last days before hatching.
Megapodes – 0%
Megapodes, like the Australian brush turkey, are exceptional in that they do no incubation at all! The parents simply bury their eggs in large mounds of rotting vegetation. The heat generated from decomposition incubates the eggs. Parental care is limited to mound maintenance.
| Species | Incubation Attentiveness |
|---|---|
| Emperor Penguins | 100% |
| Albatrosses | 80-90% |
| Bald Eagles | 99-100% |
| Cassin’s Auklets | 74% |
| Orange-cheeked Waxbills | 42% |
| Megapodes | 0% |
So in species where males assist in incubation or ambient conditions are favorable, the mothers demonstrate lower attentiveness and more frequent breaks. But they ultimately are driven by evolutionary pressures to not leave developing eggs vulnerable for extended periods. Next we’ll look at what happens post-hatching.
Does a Mother Bird Abandon Chicks After Hatching?
Once the chicks start hatching out of their shells, does the mother bird’s commitment end there?
In most species, the parents continue diligent care and feeding of their offspring for some period of time after hatching. However, the duration and intensity of post-hatching parental investment varies greatly based on the birds’ reproductive strategy.
Precocial birds like ducks and chickens have relatively self-sufficient chicks that can walk, swim, find food, and even fly shortly after hatching. Parental care tapers off quickly over a few weeks as the offspring gain independence.
In contrast, altricial birds like songbirds and owls have helpless chicks that require intensive care. The parents devote substantial time and energy to brooding, feeding, and defending the nestlings, sometimes for months. Woodpeckers may assist their young for up to a year after hatching!
In either case, the parents are hard wired to care for their chicks, at least for the period required for survival. Limited resources may force birds to make tough decisions about which offspring to feed most. However, outright abandonment of viable chicks is rare.
Some extreme examples of birds providing extended post-hatching care include:
Emperor Penguins – 4-5 Months
Emperor penguin chicks are entirely dependent on their parents for food and warmth until fledging. Males undertake the first solitary incubation shift while female penguins leave to hunt. But both parents play an equal role in rearing duties once hatching occurs. This continues until the chicks are ready to go out to sea on their own.
Laysan Albatrosses – 6 Months
One parent remains with the singleton chick at all times, sheltering and feeding it regurgitated meals. The mate travels vast ocean distances to hunt. This biparental care lasts over 6 months until the juvenile albatross is ready to take flight.
Brown Pelicans – 3 Months
Parent pelicans guard the nest and share fish captured from nearby waters with the chicks. This goes on for about 12 weeks, when the young pelicans are old enough to start diving and fishing on their own.
Bald Eagles – 3 Months
Both bald eagle parents intensely defend the nest and deliver food for their eaglets. They continue assisting for 10-14 weeks, occasionally longer, until the offspring are adept fliers and hunters.
Eurasian Oystercatchers – 1 Year
These shorebird parents guide the fledglings during migration and defend winter feeding territories on their behalf. Some offspring remain largely dependent through their first winter and into the next breeding season.
So in most bird species, the parental duties do not stop at incubation, but extend long post-hatching. The mothers are dedicated to ensuring their chicks survive to independence. Next we’ll look at special cases where bird parents do abandon their eggs or offspring.
When Do Birds Abandon Their Eggs and Chicks?
While very rare in the natural world, there are some special circumstances where bird parents may be forced to abandon their eggs or offspring:
Death of One Parent
If one parent dies during incubation or chick rearing, the other may abandon the clutch. A single parent may have difficulty successfully incubating the eggs or finding enough food for all the chicks on their own.
Loss of Entire Clutch
If a mishap leads to the full clutch of eggs being destroyed, the parents may desert the nest. Some species can re-nest and lay a new batch of eggs if it’s early enough in breeding season.
Parasitic Eggs
Birds like cuckoos will sneak their eggs into other species’ nests. If the host bird notices the foreign eggs, she may abandon the manipulated clutch and start over.
Nest Predation
Heavy predation pressure can force parent birds to desert nesting attempts earlier than normal to have time to re-nest. Some may even abandon hatchlings if the nest is frequently raided.
Insufficient Food
In times of severe food shortage, such as harsh winters or droughts, bird parents face the grim choice of which chicks have the best chance of survival. They may cut off care to weaker nestlings to conserve resources.
Human Disturbance
Excessive activity around nests by people can cause parent birds to prematurely flee the area altogether. Limiting human interference helps prevent these abandonment cases.
Inexperienced Young Birds
First-time nesters may be prone to abandoning eggs or chicks if they are unprepared for the intense commitment. Older, veteran parents rarely desert offspring barring emergency circumstances.
So in general, egg and chick abandonment is a rare last resort for parent birds. Their strong drive is to see their offspring to adulthood. Next we’ll go over how to minimize cases of abandonment.
Preventing Bird Parents From Abandoning Eggs and Chicks
Here are some tips to avoid causing parent birds to desert nests:
- Don’t approach active nests too closely. Watch activity from a distance.
- Limit noise and disruption near nesting sites during breeding season.
- Never touch eggs or chicks unless intervening in an emergency.
- Avoid prolonged photography sessions at occupied nests.
- Keep pets leashed and supervised around bird nesting habitats.
- Disable suspicious lenses, lasers, or spotlights pointed near nests.
- Remove outdoor cats from the premises during nesting season.
- Quickly replace eggs or chicks into original nests if fallen out.
- Contact a wildlife rehabilitation center if a nest is clearly abandoned.
With some common sense precautions, bird parents will feel secure continuing their vital incubation and chick rearing duties undisturbed. But it is still wise to minimize any needless disruptions.
Frequently Asked Questions
Here are answers to some common FAQs about mother birds leaving eggs and chicks:
How long can a mother bird leave her eggs?
Most birds can safely leave their eggs unattended for only brief stretches of 15 minutes up to an hour in some species. Leaving the eggs exposed for extended periods repeatedly can put them at risk.
Will a mother bird abandon her chicks if touched by humans?
She will not outright abandon healthy chicks from minor contact alone. But excessive handling against her protests may eventually force her away. Chicks should never be touched unless the nest is endangered.
Do mother hummingbirds leave their eggs?
Female hummingbirds are remarkably committed incubators. They may leave the nest for only a few minutes at a time multiple times per hour to eat and briefly stretch their wings. But they otherwise remain steadfastly on the eggs.
Why do father birds abandon their chicks?
It is uncommon for a healthy father bird to intentionally abandon his viable chicks. Apparent abandonment usually indicates either the father has died or an emergency forced him to leave the area. He likely still cares for the chicks from afar if able.
Can removing a baby bird make the mother abandon it?
Yes, a mother may stop returning to a nest if one of her chicks disappears without explanation. She may feel the area is unsafe or not worth the effort if her clutch is incomplete. Always return removed chicks quickly.
Do baby birds need their mother?
Yes, all young birds rely on their parents for food, protection, and teaching of life skills to varying degrees depending on the species. Premature separation can jeopardize a chick’s survival and development.
Conclusion
In conclusion, most mother birds have an extremely strong instinct to incubate their eggs continuously and attend to hatched chicks.
However, they may cautiously take occasional short breaks if necessary to survive themselves. Typically the fathers assist in sharing duties as well. Persistent neglect of the eggs or chicks only occurs under dire emergency circumstances. So while a mother may briefly leave her eggs in the regular course of incubation, full abandonment is exceedingly rare in healthy wild birds. With proper care, the incredible parental dedication of birds continues from egg-laying through chick-rearing.
