When it comes time for young birds to leave the nest, they and their parents may not be on the same page. As a matter of fact, they may even be at cross purposes.
Most youngsters are reluctant to leave the comfort and safety of the only home they’ve ever known, at least until they’ve achieved the ability to fly.
But most parent birds want their brood to hop out of the nest and disperse as soon as possible, to avoid the very real possibility that a predator will wipe out the young birds.
They have different goals at this point: Each young bird is thinking of its own comfort and safety, while parent birds are looking to maximize the chances that at least one of their offspring will survive to carry on their genes. Individual survival vs. species survival, it’s an evolutionary dilemma.
Parent birds don’t literally kick their youngsters out of the nest, of course. But they will try to entice them to leave, using tactics like perching on a branch nearby with a tasty insect as the bait.
This juvenile stage is a dangerous time for young birds, either way. It’s a reality of the natural world that there’s very little room for error as youngsters begin to transfer from dependence on their parents to learning to survive on their own.
Birds that leave the nest at around 10 to 14 days of age don’t yet have full flight ability, instead of fluttering around and crash landing for several weeks until their wings grow longer and stronger. They’re vulnerable to cats, crows, hawks or other predators — and predators are always watching.
Researchers at the University of Montana have studied this topic for decades and have found that fewer “early leavers” survive (compared with those that stay in the nest longer) because they lack strong flight skills. But young birds that stay in the nest longer are more likely to be eaten by a predator, because as they mature they get louder, their “feed me” screeches leading predators straight to the nest.
The birds that leave the nest early aren’t abandoned by their parents, and in fact, the dispersal of their young doubles or triples the parental workload. Adult birds must travel from youngster to youngster spread out in trees and shrubs, or on the ground at feeding time.
The workload doubles
Think of the adult robins you’ve seen hopping across the lawn, with noisy, spotty-chested offspring following behind, begging for a meal. Adult and juvenile may be at cross-purposes again, with the adult robin seeking to teach the young bird how to spot and pull up an earthworm, while the youngster just wants an easy meal delivered by a parent.
The type of nest each species builds for its family is a key factor in all this. Songbirds that hatch in a cup nest in a tree or shrub are highly vulnerable to predation and will leave the nest before they’re two weeks old. However, birds that build nests inside tree cavities or human-made nest boxes are safer from predators. These youngsters can remain in the nest until their wings are more developed. The result is that cavity nesters tend to have higher survival rates than outside nesters.
Woodpeckers, nuthatches, chickadees, bluebirds, house wrens, tree swallows — all of these nest inside cavities, while robins, cardinals, goldfinches, blue jays, catbirds and many others build their nests in the great outdoors. Some, including robins, cardinals and catbirds, hedge their bets by raising two broods during the breeding season, turning out more youngsters to try to beat the odds.
Parent birds have been raising families for millennia, they know what they’re doing and they seldom need our assistance. But we can help by keeping our cats indoors, at least during the weeks when young birds are fledging.
st. Paul resident Val Cunningham, who volunteers with the St. Paul Paul Audubon Society and writes about nature for a number of newspapers and magazines, can be reached at firstname.lastname@example.org.
Time in the nest
Cardinals: 7-13 days
Robins: 13 days
Catbirds: 10-11 days
Orioles: 11-14 days
Bluebirds: 17-21 days
Chickadees: 16 days