Tag Archives: foraging

‘Happy wife, happy life’ meaningful for birds, too

‘Happy wife, happy life’ meaningful for birds, too (Victoria University; 19 April 2017)

Research from Victoria University of Wellington has shown for the first time that wild male birds read their partner’s behaviour to appropriately cater to her food desires.

Dr Rachael Shaw, a postdoctoral research fellow in Victoria’s School of Biological Sciences, conducted a study on a group of North Island robins based at Zealandia.

The research investigated whether male robins could give their mate the type of food that she was most likely to want during reproduction.

“Robins are a monogamous, food-sharing species, so were ideal for this experiment. The experimental procedure has only previously been used in the laboratory on Eurasian jays,” she says.

“We found male robins appropriately catered to their mates’ desire, even when the female’s behaviour was the only cue available to guide their choices.

“This suggests that females can signal their current desires to their mates, enabling males to respond to that.”

Dr Shaw says the finding raises the possibility that other species might be capable of doing the same.

“In many species food sharing by the male is vital to help the female offset the energetic costs of reproduction, such as egg laying and incubation. The male’s ability to give his mate what she wants could in fact be an important factor in determining the success of a pair, as well as influencing whether they stay together. These are really exciting avenues for future research.”

The experiment first involved establishing female robins’ eating habits. “I fed the females either meal worms or wax worms, and then gave them the choice between these two types of insect larvae. I found that after the females had eaten one type of insect, they would prefer to eat the other type when given the choice. This means that the female’s desire for a particular food is affected by what she has previously eaten.”

Based on this, Dr Shaw then tested if the male would also be able to choose the type of insect his mate was most likely to want (the one she had not just eaten).

“Regardless of whether or not he had seen what his mate ate first, the male still made the appropriate choices. This suggests that the female is likely to be displaying her current desire in her behaviour, and that the male is using these cues to identify the food that she wants.”

The research, co-authored by Victoria’s Associate Professor Kevin Burns and Professor Nicola Clayton from the University of Cambridge in the United Kingdom, was recently published in the journal Scientific Reports.

The field work and data collection was carried out by Dr Shaw with help from Victoria student Regan MacKinlay. Dr Shaw’s research is supported by a Rutherford Foundation postdoctoral fellowship and a Marsden Fast Start grant from the Royal Society of New Zealand.

Odd Things Birds Eat

american robin.JPG

(Laura Erickson; 14 April 2017)

In the past few weeks, I’ve received a couple of letters from listeners about their backyard birds eating unusual items.

Craig Magnuson of Forks, Washington, wrote that he’s seen Evening Grosbeaks, during several different summers, eating cold campfire charcoal shortly after dawn at the Lake Kachess campground in the Wenatchee National Forest. He noted that someone else posted photos of Evening Grosbeaks eating campfire charcoal at a different location about 20 miles east of where he’s seen it.

True finches, such as Evening and Pine Grosbeak, crossbills, siskins, goldfinches, and Purple Finch, eat mostly seeds. This diet has two problems: birds don’t have teeth, so can’t chew seeds to mash them up, and seeds are missing many minerals and other nutrients that birds need. By eating various forms of grit, birds solve both problems. The grit remains in the first chamber of their stomach—the gizzard—for a while, helping the muscular walls to pulverize the food. And little by little, the grit itself gets pulverized, and the minerals within are picked up by the body, too.

According to the Cornell Lab of Ornithology’s Birds of North America, Evening Grosbeaks are known to eat snow, salt, and mineral-rich soil, and are drawn to areas where salt or calcium carbonate are artificially added to soil. A few studies have shown that they eat coal and coke ashes, and a scientist named Orr, in a 1951 paper titled “Observations on the birds of northeastern Idaho” in The Proceedings of the California Academy of Science, wrote that they regularly take charcoal from campfires.

Back in the 1980s and early 90s, when Evening Grosbeaks were abundant in my own neighborhood…..

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Endangered ibises benefit from joining egret flocks

(ScienceDaily, AOS; 22 March 2017)

Birds benefit from flocking together — even when they’re not of a feather. According to a new study in The Auk: Ornithological Advances, China’s endangered Crested Ibises benefit from joining forces with other, more visually-oriented bird species while searching for food.

Joining mixed-species flocks can reduce birds’ risk of predation while boosting their foraging opportunities, but it can also expose them to competition and disease, and little research has been done on what this means for birds such as ibises that rely on their sense of touch to find food. Yuanxing Ye and Changqing Ding of the Beijing Forestry University and their colleagues studied the behavior of Crested Ibises foraging with and without Little Egrets in central China’s Shaanxi Province, recording the birds’ behavior with a digital video camera to determine whether they picked up on social cues from the other species. They found that ibises in mixed-species flocks became alert to threats sooner, suggesting they felt less at risk when mingling with the more visually-oriented egrets.

Crested Ibises were once believed to be extinct in the wild, until seven birds were discovered in a remote area of China in 1981. Ye and his colleagues believe this new information about their foraging behavior could benefit ibis conservation. “Developing habitat conditions that favor mixed-species flocks may reduce the perception of risk by ibises due to the early warning effects of egrets, particularly in habitats with high levels of predation or disturbance,” according to Ye.

“Mixed-species flocks are a common occurrence in birds, but little is known about the costs and benefits of joining such groups when species differ in their foraging tactics,” adds the University of Montreal’s Guy Beauchamp, an expert on group living in birds. “In this case, ibises benefitted from joining another more visually-oriented species in that they detected threats more quickly. This study shows how detailed behavioral observations can help us understand why species forage in groups and also join other species.”