The University of Nevada, Reno, Chickadee Cognition Lab showed that supplemental feeding of wild birds has no adverse effects when the right food is used
Submitted by UNR
Chickadee Ridge, overlooking Lake Tahoe, has become a popular snowshoe and cross-country skiing destination for people hoping to feed the tiny black-capped birds, often from the palm of your hand. New research from the University of Nevada, Reno shows that as long as a few simple rules are followed, the activity doesn’t have any negative effects on the species.
“It’s a wonderful experience when the birds fly around and land on your hand to grab food,” said Benjamin Sonnenberg, a PhD student in Professor Vladimir Pravosudov’s Chickadee Cognition Lab. “We call it becoming a Disney Princess. But the question always arises as to when it is appropriate or not appropriate to feed birds in the wild.
“Our study shows that supplementation has no significant impact on wild mountain tit populations in the Sierra Nevada. However, you have to be careful about what and how you feed the birds.”
The birds should only be given food similar to what they will find in their natural environment, such as unsalted pine nuts or black oil sunflower seeds, and they should never be fed human food such as bacon or bread.
“And always be respectful of the animal,” said Sonnenberg, a member of the biology department. “Don’t try to catch the birds, give them their place. Act like you are at her house visiting her.”
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 tits at two elevations in the Sierra Nevada for six years. When comparing the breeding performance of the birds that used feeders placed in the forest with those that did not, the researchers found no significant difference in reproduction between the two groups.
“If we see an increase in population size or a decrease in population size, it could mean that we injured the animals by feeding them,” said postdoctoral researcher Joseph Welklin. The team, based in the College of Science, saw neither. “Our study shows that winter feeding of these mountain tits in the wild does not affect their population dynamics.”
The team was able to closely monitor the brood and behavior of the tits using radio frequency identification technology. By tagging birds with passive embedded transponders, or PIT tags, they were able to track the birds that were using and not using the bird feeders, as well as monitor nest boxes that were scattered throughout the forest.
Over six years, the researchers measured the number of eggs the birds laid and the number of nestlings that successfully hatched. They saw no differences in the growth or decline of the tit population.
The reason the extra feeding has no effect is likely due to the titmouse’s impressive abilities to store or cache food. The birds rarely eat the food they take from feeders or from a person’s hand right away, but hide it for later consumption.
“One of the wonderful things to do at Chickadee Ridge is to watch chickadee behavior,” Sonnenberg said. “If they get on your hand and grab a food item, if they fly off into the woods and you can’t see them anymore, they’re probably saving that food for later. You can even see them sticking a nut under a piece of bark or in the needles of a lodgepole pine. Most of the food you feed those birds in Chickadee Ridge they don’t eat right now.”
The seemingly delicate birds are one of the few bird species that can survive the cold Sierra Nevada winters and not migrate to a warmer climate. One of the ways they can do this is by hiding hundreds of thousands of seeds in the forest to use as a food source during the winter months. They have incredible memories and can remember numerous cache locations.
“It appears that memory performance, and not just the amount of food they cache, directly influences winter survival in tits,” Sonnenberg said. “Even if people feed more food to tits and store more food, they may not survive the winter if they don’t have good spatial memory.”
The Chickadee Cognition Lab has extensively studied bird cognition and shown that a bird’s memory is closely linked to its ability to survive and thrive. The birds have another unique trait that helps them survive the harsh winter months.
“At night, when it gets very cold and they can’t move or find food, they lower their body temperature by three or four degrees, which saves them 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 keep finding and caching seeds throughout the mountain.”
Implications for Backyard Birdhouse Enthusiasts
The results add to the growing evidence that supplemental feeding alone, isolated from the effects of the urban environment, 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 birdhouse enthusiasts. More than $4 billion is spent on hobby bird feeders each year in the United States alone, the study finds.
By following similar guidelines for feeding in natural settings and providing appropriate food, backyard bird feeders should have minimal impact on tit populations.
More research is needed to confirm similar effects on other species that are frequent backyard visitors. Since bird feeders bring birds into more close contact than they would naturally, regular cleaning of bird feeders is recommended.
“Look for things like abnormal growths on birds’ beaks and feet that could be a sign of disease,” Sonnenberg said. “You should clean your feeders with a solution of bleach and water at least several times during the winter, if not every few weeks.”
With this research, those who enjoy watching birds at feeders in their backyard or hiking through the snow to Chickadee Ridge can continue to enjoy these activities knowing the birds they feed are not being harmed.