Latest news with #AnimalBehaviour
CBC
7 days ago
- Science
- CBC
These bird moms lay their eggs in other species' nest, and never come back for them
When a female cowbird is ready to have a baby, she'll stake out another bird's nest, wait until the coast is clear, then slip in, stealthily lay her egg and leave it behind for another family to raise. Most other baby songbirds in that situation would imprint on their adoptive mothers and grow up believing they were members of another species. Cowbirds, however, have no such identity crises. "It's very clear that at a certain age they get very tired of their host parents and they want to get out of town," Mac Chamberlain, an ornithologist at the University of Illinois Urbana-Champaign, told As It Happens. Previous research suggested that once the chicks were reared, their biological mothers would come back for them and teach them how to be cowbirds. But a new study, published in the journal Animal Behaviour, found that's not the case. While they do eventually find other members of their own species, they get along just fine without mom. Brood parasites Cowbirds are what's known as brood parasites, meaning they allow other species to rear their young, often to the host nest's detriment. Some birds are clever enough to recognize an unfamiliar egg in their midst and get rid of it. But once the cowbird hatches and starts squawking for food, most mothers will instinctively feed them, none the wiser of the deception. Less than one per cent of bird species worldwide use this mating strategy, Chamberlain said. "It's very cool and it's very novel, I think, compared to other birds," he said. Some brood parasites, like cuckoo birds, go on a killing spree the minute they hatch, pushing their host siblings out of the nest to their untimely deaths so they don't have to compete for resources. "Cowbirds are unique in the fact that they're nest sharers," Chamberlain said. "The only harm they really do to their nest mates is just being an extra mouth to feed." While not as brutal as cuckoos, it's still not great for the host family. "Cowbirds hatch earlier and start begging, many have argued, more frequently and more intensely [than their nest mates], and so they end up getting more food," Matthew Louder, a former scientist who studied brood parasites at Texas A&M University, told CBC. "If you cannot bring enough food to feed your other ones, you might lose some of the other offspring." If they reunite with mom, it's probably random chance Within about a month, the little imposters leave the nest for good. From there, Chamberlain says they have a short window to find an adult cowbird and learn the ropes before grouping together to migrate south. It's not clear what happens if they don't find an adult in time, but Chamberlain says cuckoos who fail in this quest never learn their species-specific behaviours and local dialect, and end up ostracized from their flock. In a 1995 study, researchers found and trapped pairs of adult and juvenile brown-headed cowbirds, sampled their blood, and discovered many of these duos were related. The authors theorized the juvenile cowbirds were reuniting with their mothers before flying south. The mothers, they suggested, may even keep watch over their hatchlings from afar, then lead them out of the nest when it's time. But this latest study was not able to reproduce those findings. Researchers spent three years capturing and genetically testing brown-headed cowbirds — 122 adults and seven juveniles altogether — and found the young birds were more likely to be found with unrelated female adults. Scientists believe the juveniles find and latch onto adult females, in part, because they have similar looking plumage, but also because they're instinctively drawn to their chattering calls. Louder says he was not surprised by the findings. In his own research, he says he'd already shown that juvenile cowbirds leave their nests all on their own. But Chamberlain says this doesn't mean the 1995 study was flawed. This new research, he says, was conducted in Illinois, where cowbirds are more populous than on the east coast, where the previous study was carried out. "If you're .... in an area where there's only really one breeding female cowbird, if you bump into a female cowbird, it's likely going to be your mom," he said. Stephen Rothstein, a professor emeritus at the University of California Santa Barbara who wasn't involved in the study, says while the methodology is sound, the sample size of juveniles is too small to draw any hard conclusions. Nevertheless, he said in an email that he agrees juvenile cowbirds are "unlikely to have a mechanism by which they can identify their biological parent from another adult cowbird." But since cowbirds have defined territories, he says it's possible they'll meet their parents again, just by random chance. While some might find this breeding strategy cold, the people who study cowbirds defend them passionately. They're a native species doing what they're meant to do, says Louder, and they're no more cruel than hawks and other birds of prey who snatch up other birds or eggs to eat. Except in rare circumstances where cowbirds heavily outnumber an endangered species, he says, they don't pose population-level threats to other birds.
New York Times
03-07-2025
- Science
- New York Times
How a Parasitic Bird With No Parents Learns What Species It Is
In P.D. Eastman's classic picture book 'Are You My Mother?' a baby bird hatches alone and goes on a quest. It asks a cow, a dog, and even an excavator whether they might be its mother. Finally, the chick and its true mom reunite. In nature, cowbirds also hatch without their parents present. Cowbird mothers leave their eggs behind in the nests of different species. Yet to grow up safely, the birds must join other cowbirds in flocks. They somehow need to learn what species they belong to. Earlier research hinted that brown-headed cowbird chicks might reconnect with their parents. But a paper published Thursday in the journal Animal Behaviour found no evidence of a happy reunion. Instead, cowbird chicks learned who they were by hanging out with unrelated adult females. Brown-headed cowbirds are what scientists call brood parasites. That means parents don't raise their own young. Mothers sneakily lay eggs in other birds' nests, and oblivious host parents rear the young brood parasite alongside their own offspring. (Chicks of the common cuckoo, another brood parasite, kill their foster siblings by shoving them over the side of the nest.) Unlike most birds, a young brood parasite doesn't get attached to its host parents. You can see this if you rear cowbirds by hand, said Mark Hauber, a comparative psychologist at CUNY Graduate Center in New York: 'They start hating you at some point.' If a cowbird imprinted on a family of yellow warblers, say, and sought out warblers' company as an adult, it would never find a mate and reproduce. Beyond mating, 'There's tons of different benefits to knowing what kind of bird you are,' said Mac Chamberlain, an ornithologist at the University of Illinois Urbana-Champaign who works with Dr. Hauber. For example, cowbirds flock together, roost together and learn from each other where to find food. Want all of The Times? Subscribe.
BBC News
16-06-2025
- Science
- BBC News
Birds listen in on prairie dog calls to stay safe
If we told you that some birds listen in on the calls of prairie dogs, you might think they should keep their beaks what if we told you that they are doing it to stay safe?Prairie dogs, which are rodents and are closely related to squirrels, bark to let each other know if there are predators have found that these calls are being picked up and used by long-billed curlews too. Prairie dogs are hunted by a long list of predators from birds of prey to foxes and even large curlews are vulnerable to some of these predators too. Research, which was published in the journal Animal Behaviour, found the birds listen to the sounds of the rodents to find out if predators are on the gives them more time to react to the nearby danger. Long-billed curlews nest their eggs in short grass on the ground, and when they hear the prairie dog call, they get as low as possible and try to camouflage part of the research, a team made a fake predator, in the form of a stuffed badger on a remote controlled was then driven towards nests in Montana in the US, sometimes while playing the calls of prairie dogs, sometimes in silence. When the birds could hear the fake barks from the remote-controlled badger, theyducked down into the grass to hide when it was more than three times the distance away, compared to when no barks were played.
Yahoo
20-04-2025
- Health
- Yahoo
Experts stunned by bizarre reaction from birds exposed to unusual disturbance: 'Significant impact'
In a new study published in the journal Animal Behaviour, scientists observed a worrisome behavioral change in the Galápagos yellow warbler, a bright yellow songbird native to the Galápagos Islands. Researchers found the birds are behaving more aggressively — and it appears to be linked to human-induced noise in their habitat. As Anglia Ruskin University reported via researchers conducted a study in the Galápagos Islands, where they played recorded traffic noise at 38 locations home to the yellow warblers. What they discovered was that the more traffic the warblers had been exposed to, the more aggressively they responded to the sounds. The behavior was even observed in birds on Floreana Island, which has only 10 cars — showing that it doesn't take much noise pollution to seriously affect wildlife. "Our study shows the importance of considering behavioral plasticity in conservation efforts and developing strategies to mitigate the effects of noise pollution on wildlife," said co-author Caglar Akcay, a senior lecturer in behavioral ecology at ARU. "It also highlights the significant impact of human activities on wildlife behavior, even in relatively remote locations such as the Galápagos Islands." Noise pollution can stress animals, alter their behavior, and disrupt their communication methods — one reason researchers believe these yellow warblers become more physically aggressive. When this happens, the negative consequences can ripple across ecosystems. Not only does noise pollution affect wildlife, but it's also unhealthy for humans. According to the Environmental Protection Agency, studies have found direct links between noise pollution and health issues such as high blood pressure, sleep loss, loss of productivity, and stress-related illnesses. Protecting wildlife from noise may also mean creating healthier spaces for ourselves. Researchers say we should proactively address noise pollution to better protect ourselves and the environment. Some strategies include creating buffer zones, regulating traffic near wildlife areas, and raising public awareness. Government regulation helps on a broader scale — for example, the European Commission included minimizing noise pollution in its Zero Pollution Action Plan. Also, nonprofits, including the Noise Pollution Clearinghouse, raise awareness and work for stronger laws to control noise pollution. Individuals can also help. Supporting policies that prioritize green spaces, buffer zones, and quieter transportation; walking or biking instead of driving; and practicing a quieter version of "leave no trace" while in nature are all meaningful steps. Investing in cleaner, quieter technologies such as electric vehicles and sustainable public transit can make a big difference — not just for people but for wildlife too. Do you worry about air pollution in and around your home? Yes — always Yes — often Yes — sometimes No — never Click your choice to see results and speak your mind. Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.
Yahoo
21-03-2025
- Science
- Yahoo
Traffic noise is making these Galápagos birds more aggressive
While actual road rage is primarily a human trait, some birds on the Galápagos Islands are experiencing their own issues with traffic. Galápagos yellow warblers (Setophaga petechia aureola) that are exposed to noisy traffic appear to show heightened levels of aggression. The findings are detailed in a study published March 20 in the journal Animal Behaviour. 'Birds use song during territorial defence as an aggressive signal,' Caglar Akcay, a study co-author and behavioral ecologist at Anglia Ruskin University in the United Kingdom, said in a statement. 'However, if external noise such as traffic interferes with the signalling, effectively blocking this communication channel, increasing physical aggression would be an appropriate response.' A world-renown 'natural living laboratory,' the Galápagos Islands are over 500 miles off the coast of Ecuador. During his famed voyage to the archipelago aboard the HMS Beagle, the Galápagos helped inspire Charles Darwin's theory of evolution by natural selection. The archipelago is home to a large number of unique and endemic species including giant Galápagos tortoise, marine iguana, flightless cormorant, and the Galápagos yellow warbler in this new study. The small yellow songbird is widespread on the archipelago. It is also genetically distinct from yellow warblers found elsewhere in the Americas and is classified as a subspecies. However, the human population and impacts on the Galápagos has significantly grown in recent years. Alongside a jump in tourism, the population of permanent residents is also increasing by over 6 percent per year, leading to more motor vehicles around the islands. This new study took a closer look at the impact of vehicle noise pollution on the Galápagos yellow warblers. To stimulate the sound of an intruder, the team played bird songs from a speaker and recorded traffic noise. These noises were recorded at 38 locations populated by Galápagos yellow warblers on the islands of Floreana and Santa Cruz. Twenty of the sites were within 164 feet (50 meters) of the nearest road and 18 were over 328 feet (100 meters) away. Male Galápagos yellow warbler on the island of Floreana – filmed by Caglar Akcay in March 2025. CREDIT: Caglar Akcay, Anglia Ruskin University. The team then measured their song–which is typically used to ward off intruders–and their physical and aggressive behaviors. These actions include making repeated flights across the speaker or approaching it closely. During trials that included traffic noise, the team found that Galápagos yellow warblers living in roadside territories showed increased aggression. Those living away from the roads had a decreased aggression relative to trials without noise from cars. 'Our results show that the change in aggressive responses in yellow warblers occurred mainly near roads. Birds occupying roadside territories on both islands, and therefore having regular experience of traffic noise, may have learned to increase physical aggression when the territorial intrusion was accompanied by traffic noise,' said Akcay. [ Related: Noise pollution messes with beluga whales' travel plans. ] This effect of living on a roadside territory was even present on Floreana Island, which only has about 10 vehicles on it. According to the team, this suggests that even minimal experience of car traffic affects responses to noise. The Galápagos yellow warblers on the more populous island of Santa Cruz also increased the duration of their song when confronted by traffic noise. Long-term selection based on noise experience, or an individual bird's previous experience of noise could allow the birds to adapt and adjust parts of their songs. 'We also found some evidence of birds trying to cope with noise by adjusting their song, with yellow warblers in all habitats increasing the minimum frequency of their songs to help them be heard above the traffic noise,' said Akcay. The birds also increased the minimum frequencies of their songs during the noise experiments, whether or not their territory was close to the road. This helped reduce any overlap of their songs with the low-frequency traffic noise. 'Our study shows the importance of considering behavioural plasticity in conservation efforts and developing strategies to mitigate the effects of noise pollution on wildlife,' said Akcay. 'It also highlights the significant impact of human activities on wildlife behaviour, even in relatively remote locations such as the Galápagos Islands.'
