University of Nevada, Reno’s Chickadee Cognition Lab showed supplemental feeding of the wild birds had no negative impacts when proper food is used
Submitted by UNR
Chickadee Ridge overlooking Lake Tahoe has become a popular snowshoe and cross-country ski destination for people hoping to experience feeding the tiny black-capped birds, often from the palm of one’s hand. New research from the University of Nevada, Reno shows the activity has no negative impact on the species as long as a few simple rules are followed.
“It’s a wonderful experience when the birds fly around and land on your hand to grab food,” Benjamin Sonnenberg, a doctoral student in Professor Vladimir Pravosudov’s Chickadee Cognition Lab, said. “We call it becoming a Disney princess. But there’s always the question of when it is appropriate or not appropriate to feed birds in the wild.
“Our study shows that supplemental feeding has no significant impact on the populations of wild Mountain Chickadees in the Sierra Nevada. However, you must be careful of what and how you’re feeding the birds.”
The birds should only be given food similar to what is found in their natural environment such as unsalted pine nuts or black-oil sunflower seeds and they should never be fed human food like bacon fat or bread.
“And always be respectful of the animal,” Sonnenberg, a member of the Department of Biology, said. “Don’t try to catch the birds, give them their space. Behave like you’re in their house and you’re visiting them.”
The research led by Sonnenberg and postdoctoral researcher Joseph Welklin, published in the January 2023 issue of the science journal Ornithology, tracked a population of wild Mountain Chickadees at two elevations in the Sierra Nevada over six years. When comparing the breeding performance of the birds who used feeders placed around the forest to those that did not, the researchers saw no significant difference between the two groups’ reproduction.
“If we saw increases in the population size or decreases in the population size, that could mean we were hurting the animals by feeding them,” postdoctoral researcher Joseph Welklin said. The team, based in the College of Science, saw neither. “Our study shows that feeding these mountain chickadees in the wild during the winter has no effect on their population dynamics.”
The team was able to closely monitor the chickadee breeding and behavior using radio frequency identification technology. By banding birds with Passive Integrated Transponders, or PIT tags, they were able to track the birds that used and didn’t use the feeders as well as monitor nesting boxes placed throughout the forest.
Over six years, the researchers measured the number of eggs the birds laid and the successful nestlings they hatched. They saw no differences in chickadee population growth or decline.
The reason the supplemental feeding has no impact is likely due to the chickadees’ impressive food storing, or caching, abilities. The birds are rarely eating the food taken from feeders or from a person’s hand immediately but are hiding it for later consumption.
“One of the wonderful things you can do at Chickadee Ridge is to observe chickadee behavior,” Sonnenberg said. “When they come to your hand and grab a food item, if they fly away into the woods and you can’t see them anymore, they are likely storing that food for later. You might even see them stick a nut underneath a piece of bark or in the needles of a Lodgepole Pine. Most of the food you give these birds at Chickadee Ridge – they’re not eating in the moment.”
The seemingly delicate birds are one of the few avian species that stick out the cold Sierra Nevada winters and do not migrate to a warmer climate. One of the ways they can do this is by hiding hundreds of thousands of seeds around the forest to use as a food source during the winter months. They have incredible memories and are able to remember numerous caching locations.
“It appears that the memory ability and not just the amount of food they cache directly affects chickadees’ overwinter survival,” Sonnenberg said. “So, even if people feed chickadees more food and they cache more food, if they don’t have good spatial memory, they may not make it through the winter.”
The Chickadee Cognition Lab has studied the cognition of the birds extensively, showing that a bird’s memory is closely tied to its ability to survive and thrive. The birds have another unique characteristic that helps them survive the harsh winter months.
“At night when it gets really cold and they can’t move around and find food, they lower their body temperature by three or four degrees, saving up to 30% of their metabolism throughout the night,” Welklin said. “They save their energy for the morning when they wake up with the sun and they go out to continue finding and caching seeds all over the mountain.”
Implications for backyard bird feeder enthusiasts
The results add to growing evidence that supplemental feeding alone, isolated from the effects of urban environments, may have little to no impact on the population dynamics of some bird species. This is good news for visitors to Chickadee Ridge, but it also has implications for backyard bird feeder enthusiasts. More than $4 billion are spent on hobby bird feeders each year in the United States alone, the research notes.
By following similar guidelines for feeding in natural environments and providing appropriate food, backyard bird feeders should have minimal impact on chickadee populations.
More research is needed to confirm similar effects on other species that are common backyard visitors. Because bird feeders bring birds in close contact with one another more than would occur naturally, regular cleaning of feeders is recommended.
“Keep an eye out for things like abnormal growths on birds’ beaks and feet that could be a sign of disease,” Sonnenberg said. “You should be cleaning your feeders with a bleach and water solution at least several times a winter if not every couple of weeks.”
With this research, those who enjoy watching birds at feeders in their backyard or trekking through the snow to Chickadee Ridge can continue to enjoy these activities knowing the birds they are feeding will not be harmed.
