- There are some birds known as parasites that lay their eggs in other birds’ nests in order to force the other birds to raise their young.
- Unlike some parasitic birds, indigos and widaes do not destroy host eggs. Instead, the female simply mixes the eggs with the host.
- Female honey guides lay a single egg in multiple nests. By doing so, she spreads the risk across multiple hosts and ensures that more eggs survive.
- The cuckoo is easily one of the best known and most studied parasitic birds. Disguised as a sparrowhawk, it bullies a bird out of its nest so it can lay its eggs.
Many birds take great care of their eggs and go to great lengths to protect them. The female may sit in the nest for weeks, while the male guards the eggs and forages for food. That said, several notorious bird species take different approaches. Rather than incubating eggs themselves, these birds rely on other birds to incubate and raise their young. These birds, known as parasites, lay their eggs in other birds’ nests, employing a number of shady tactics. Some will rely on deception to trick other birds into raising their young. At the same time, like old world mafias, some birds will bully other species into caring for their eggs. In fact, some even terrorize other birds and may destroy the host bird’s eggs. Although rare, this behavior is well documented and worth exploring further. Here is a list of 5 bird species that lay their eggs in other birds’ nests.
#5: Brown-Headed Bullbird
Brown-headed bullbird (canary) is a small parasitic bird native to North America.It is a member of the Icterid family of New World blackbirds, belonging to the genus catfish. Although the genus includes five other species, the brown-headed bullbird is the type species of the genus. In ancient Greek, the genus name translates as “battle of pregnancy,” which is certainly fitting. Brown-headed bullbirds lay their eggs in the nests of other small birds such as American robins, hummingbirds and some birds of prey. While most brood parasites target one or a few species, brown-headed bullbirds take a more general approach. According to field studies, they target the nests of as many as 220 host species. This makes them one of the most prolific parasitic species known in the world.
When the host bird leaves the nest, the female brown-headed bullbird sneaks in to lay her eggs. If a host bird rejects a cowbird egg, the brown-headed cowbird female may retaliate by destroying the host’s egg. Hosts that do not notice the cowbird eggs will unknowingly hatch and feed the cowbird offspring. Because cowbird offspring hatch quickly, they will often hatch before the host’s eggs. They also grow fairly quickly, which gives them an advantage over their host’s eggs in terms of obtaining food. This often results in starvation of the host’s hatchlings. However, some species such as the brown thrush, gray cat thrush, and yellow warbler almost always reject eggs or expel the young of the bullthrush. The surviving brown-headed cowbird juveniles grow up to be able to recognize the calls of other cowbirds. This enables them to return to the cowbird flock after leaving their host’s nest.
#4: Indigo Bird
The indigo bird is native to Africa and belongs to the songbird family Songbird family. In addition to indigo birds, the Viduidae family also includes fellow parasites whydah and cuckoo finches. Indigo birds generally look like finches, with most plumage in black or indigo. To tell the difference between an indigo bird and a Wyda bird, just look at their tails. Male whydahs grow long tail feathers, while male indigo birds do not. Indigo birds lay their eggs in the nests of Old World finches. Indigo birds, in particular, tend to use plum finches as hosts. In general, indigo birds take flamingos as hosts, while Wyda birds prefer to target flamingos.
Unlike some parasitic birds, indigos and widaes do not destroy host eggs. Instead, the female simply mixes the eggs with the host. Typically, females lay 2-4 eggs at a time. Because the eggs of blue tits, widae and plum finches are all white, it is difficult for host birds to tell whose eggs belong to whom. Bluebird and Wyda eggs are actually slightly larger in size, but the difference is small. The larva learns to imitate and recognize the vocalizations of the host species. As adults, male hatchlings use this information to express their interest in potential female mates, continuing the cycle of mating and parasitism.
#3: Honey Guide
Honeyguides are found in southern Africa, the foothills of the Himalayas and Malaysia. Also known as pointing birds or honeybirds, honey guides are named for their unusual behavior. These dimly colored little birds deliberately lure humans into their hives so they can eat their favorite foods — beeswax and grubs. Of the 17 species of honey guides so far, only the large honey guides are known to exhibit this behavior. On the other hand, there is evidence that half of all honey guides are brood parasites. They are specific to birds such as walleyes, warblers, swallows, bee eaters, barbets and starlings.
In these eight species, female honey guides lay a single egg in multiple nests. By doing so, she spreads the risk across multiple hosts and ensures that more eggs survive. Occasionally, female honey guides may kill the host’s eggs before laying them. Regardless, females spend time incubating their eggs before laying them in their host’s nest. They do this so that their offspring hatch before the host’s eggs. Larger honey guide chicks will destroy the host’s eggs or kill the host’s newborn hatchlings. It does this by stabbing its host’s young with sharp barbs in its beak.
#2: Blackheaded Duck
Black-headed ducks are found in the swamps and lakes of Chile, Paraguay, Uruguay, Argentina, and Brazil. It belongs to the family Anatidae, but is so far the only member of the genus, Different internal medicine. Unlike the closely related hard-tailed duck, the black-headed duck has a soft tail and a flat bill. The species takes its name from the males, which have black feathers on their heads and mantles. Although relatively small and unremarkable in appearance, female black-headed ducks pack an abundance of guts. They do not build nests but lay their eggs in the nests of other birds. They target pochards, black-capped ducks, and ducks, although they occasionally use the nests of seagulls and some birds of prey.
Unlike some brood parasites, female black-headed ducks do not use aggressive tactics against their hosts. Instead, they just let their eggs hatch peacefully with those of their host. In addition, the offspring of the black-headed duck do not prey on the young of the host. By the time they hatch, the black-headed ducklings are basically able to fend for themselves. Since they leave the host’s nest soon after hatching, it is not necessary to kill the host’s offspring to increase their chances of survival.
#1: Common Cuckoo
The cuckoo is easily one of the best known and most studied parasitic birds. It belongs to the cuckoo family, which includes roadrunners, rhododendrons, American cuckoos, marcohas, and fennel. Cuckoos are found throughout Asia and Europe, and migrate to sub-Saharan Africa and South Asia in winter. Their name comes from the distinctive onomatopoeia calls that males make. Males usually appear completely gray, while females may appear gray with pink highlights or reddish-brown. Common cuckoos have a hawkish appearance, relying on mimicry to help them target the nests of their host birds. By camouflaging themselves from predators like the European sparrowhawk, females can gain access to their host’s nest to lay their eggs. Using this tactic, they have invaded the nests of more than 100 different host species, including warblers, redstarts, pipits, robins and fulmars.
Throughout the breeding season, a female cuckoo may lay her eggs in dozens of different nests. Sometimes a common cuckoo female targets hosts whose eggs look similar to her own. This increases the chances that the host bird will not reject the cuckoo eggs or abandon the nest. Once the cuckoo offspring hatch, they typically push the host’s eggs out of the nest. Likewise, cuckoo chicks will also push the host’s chicks out of the nest if the host’s eggs hatch first. By eliminating competition, the cuckoo chick ensures that it monopolizes all the food it needs to grow.
I am broadly interested in how human activities influence the ability of wildlife to persist in the modified environments that we create.
Specifically, my research investigates how the configuration and composition of landscapes influence the movement and population dynamics of forest birds. Both natural and human-derived fragmenting of habitat can influence where birds settle, how they access the resources they need to survive and reproduce, and these factors in turn affect population demographics. Most recently, I have been studying the ability of individuals to move through and utilize forested areas which have been modified through timber harvest as they seek out resources for the breeding and postfledging phases. As well I am working in collaboration with Parks Canada scientists to examine in the influence of high density moose populations on forest bird communities in Gros Morne National Park. Many of my projects are conducted in collaboration or consultation with representatives of industry and government agencies, seeking to improve the management and sustainability of natural resource extraction.
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