Baby birds open their mouths for a very important reason – to beg for food from their parents! When baby birds hatch from eggs, they are helpless and rely completely on their parents to feed them. They open their mouths wide and start peeping loudly to signal to their parents that they are hungry and need to be fed. This behavior is called gaping.
Why Do Baby Birds Gape?
There are a few key reasons why baby birds gape:
1. To stimulate the parent to regurgitate food
When parent birds see their chicks with mouths agape, it triggers their instinct to feed them. The visual cue of the open mouth combined with the baby’s loud calls stimulates the parent to regurgitate food from their crop to feed the chicks. Regurgitation is how parent birds feed their young, especially in the first few days after hatching.
2. To compete with siblings for food
Baby birds often hatch with siblings who they have to compete with for their parents’ attention and food. Chicks that gape the widest and beg the loudest tend to get fed first and most often. Gaping is a way for each chick to signal that they are the hungriest and in greatest need of the next morsel of food.
3. To direct the parent where to aim the food
Parent birds have to carefully aim the regurgitated food from their beak into the chick’s mouth. The gaping behavior helps guide the parent’s aim towards the mouth. It makes a clear opening target for the parent to drop the food into. Chicks will often stretch their necks upwards and gape towards an approaching parent to facilitate easier feeding.
4. To dissipate heat
Opening the mouth also helps baby birds regulate their body temperature. Baby birds cannot control their temperature well in the first weeks after hatching. Gaping allows excess body heat to dissipate through the mouth and throat. This is especially important when chicks are clustered together in a nest.
What Do Baby Birds Do When Gaping?
Baby birds perform some very specific and strategic behaviors when gaping to get their parents’ attention and maximize their chances of being fed:
Fluttering wings
Chicks will often flutter or lightly flap their developing wings while gaping. This extra movement can help get the parents’ attention and show that they are robust and healthy chicks worthy of feeding first.
Waving heads from side to side
Head bobbing or weaving from side to side while gaping helps make chicks more visible to parents looking down at the nest. The head movements exaggerate the mouth opening.
Jostling or pushing forwards
Gaping chicks will jockey for position by pushing themselves forward over siblings to get closest to the parent. This positioning helps ensure they get the food first.
Loud calling
Peeping or chirping loudly while gaping signals hunger urgency to the parents. It is a form of acoustic begging which draws attention. The hungriest chicks tend to call the most.
Posturing upwards
Chicks gape with their necks stretched upwards and bills pointed to the sky to make it as easy as possible for the parents to deliver food straight downward into their mouths.
When Does Gaping Behavior Begin and End?
Gaping starts immediately after hatching and continues for about two weeks until the chicks are mature enough to start eating on their own.
Hatching to 3 days
Right after breaking out of their shell, chicks are totally dependent on their parents for survival. They gape strongly to induce frequent feedings.
4 days to 2 weeks
Chicks continue gaping but start spending more time sleeping and resting between feedings. Gaping becomes focused around feeding time.
2 to 4 weeks
Less gaping is needed as chicks start exploring their environment and testing out food. Parents still feed but chicks can survive longer between meals.
1 month onwards
Chicks rely completely on self-feeding. Gaping stops unless chicks become injured or ill and need a bit of extra help from parents.
Why Do Some Species Gape More Than Others?
The strength of gaping behavior varies across bird species based on factors like:
Nest type
Species that nest in cavities or enclosed nests (like woodpeckers) tend to gape less strongly. Parents can easily find chicks in a small space so exaggerated gaping is not as important. Ground-nesting species exposed to the elements generally gape more to stand out.
Colony size
In larger colonies, parents can have difficulty locating their own chicks. Chicks gap more strongly to get noticed and fed in a crowded colony. Gaping is less important in smaller, less dense colonies.
Feeding frequency
Species that feed chicks less frequently induce stronger gaping to incentivize each feeding. Species that feed frequently see less intense gaping between meals.
Chick maturity
Precocial chicks that hatch quite developed gape less than altricial chicks that hatch small and helpless. Altricials rely more on gaping to survive.
| Species | Nest Type | Colony Size | Feeding Frequency | Chick Maturity | Gaping Intensity |
|---|---|---|---|---|---|
| Woodpeckers | Cavity | Small | Frequent | Precocial | Low |
| Seagulls | Ground | Large | Infrequent | Semi-precocial | High |
| Songbirds | Tree nest | Medium | Medium | Altricial | Moderate |
This table compares different bird species and how traits like nest type, colony size, feeding frequency, and chick maturity impact the intensity of gaping seen.
How Has Gaping Evolved in Birds?
Ornithologists believe gaping behavior evolved predominantly through natural selection pressures:
Visibility
Species whose chicks gaped the most strongly and visibly tended to get fed more, survive and pass on gaping behaviors.
Begging intensity
Louder, more exaggerated gaping translates to more feedings, fueling the evolution of conspicuous gaping displays.
Parent-chick communication
Mutually reinforcing parent-chick interactions drove the development of gaping as a signaling system.
Hatching synchrony
In many species, chicks hatch together and compete for food through gaping, selecting for strong gaping instincts.
Interesting Facts About Gaping
Chicks gape before even hatching
Late-stage embryos can gape inside the egg as practice before hatching. Parents may gape back to stimulate hatching.
Some blind chicks gape
Even naturally blind chicks like vultures gape, showing gaping is innate rather than learned.
Gaping continues after leaving the nest
Even fledged chicks may continue gaping for a short while when parents arrive with food.
Adults may gape for food sharing
Adult birds sometimes reciprocally gape to share food with their mates or offspring.
Nest parasites mimic gaping
Some birds like cuckoos exploit host parent instincts by mimicking gape-like begging calls.
Conclusion
In summary, baby birds gape instinctively to signal hunger, compete for feedings, guide parents, and regulate temperature. The gaping behaviors like wing fluttering, head bobbing, vocalizing, and posturing stimulate parents to offer regurgitated food. Gaping starts right after hatching and continues for around 2 weeks until chicks mature and self-feed. Species that nest openly, live in large colonies, are fed less frequently, or are altricial tend to gape more strongly. Natural selection likely drove the evolution of conspicuous gaping in birds. This essential behavior ensures baby birds get the food they need to survive and successfully leave the nest. Understanding gaping gives us insight into the complex parent-child dynamics and evolutionary strategies of our fine feathered friends.
