The impacts of supplemental feeding on bird populations
Highlights from a presentation by FeederWatch project leader, Emma Greig, at the North American Ornithological Conference 2016. She summarized research being conducted by her and by Cornell Lab Citizen Science director, David Bonter.
Food is a major determinant of the distribution, evolution, behavior and persistence of species, as has been shown by an abundance of supplemental feeding studies on small scales. But despite 50 million people in the US offering billions of pounds of seeds to birds every year, we know very little about the consequences of this hobby on native species in North America.
If supplemental feeding is ecologically detrimental, then we would expect to see long-term population declines in the species that consume the most supplemental food. According to the State of North America’s Birds 2016, one-third of all North American bird species need urgent conservation action. We looked at 30 years of FeederWatch data collected by thousands of project participants to select 135 species using feeders occasionally to regularly. Then we looked at the population trends for those species using 50 years of Christmas Bird Count data.
Overall, species that utilize bird feeders the most were doing better over time, rather than worse, and the few species showing declines include non-native species (House Sparrow, European Starling) or species suffering from novel diseases (House Finch). The species most in trouble, such as seabirds and shorebirds, don’t come to feeders and are declining because of other threats. Feeding birds may not help the hardest-hit species, but it may inspire people to support conservation.
We still have a lot to learn about the impacts of feeding birds, such as possible indirect effects on migratory species, or possible effects on generalist predators such as crows that may subsequently impact populations of non-feeder birds or small animals. Nonetheless, this work gives us some insights about how feeding birds impacts the species that use feeders the most.
29 comments on “The impacts of supplemental feeding on bird populations”
I used to have many feeders but I had read/heard while living in Ithaca that you were disrupting the natural feeding of the birds, taking them off their ‘course’. So, I have discontinued having feeders, tho’ I miss watching the birds. I do put out suet in the winter. Is this true?
Hi Nancy,
Feeding birds does not affect their migration. Only a small percentage of their diet is derived from food provided by humans. You can read more @ https://www.allaboutbirds.org/should-i-stop-feeding-birds-in-fall-so-they-can-start-their-migration/.
Well I am all for feeding birds, but I do think it affects migration. Otherwise the Cardinals and Blue Jays would not be able to survive through the Winter in the North without feeders given the frozen ground..
They would be able to survive, they have through thousands of years of evolution towards their range and migration patterns. Cardinals and Blue Jays aren’t seasonal migrants anyways. The cardinals that live in New York state are savvy enough to live there year-round and find food just fine, as they have always done ever since they finished evolution in North America. The Chickadees that live in Alaska live there year-round because they can handle it and it’s what the species has always chosen to do. Birds are self-sufficient and we just study and watch them and maybe if we’re lucky they’ll stop by our man-made feeders for the nutrition they could easily find on their own that would probably be better quality too. The most common recommendation is to take down hummingbird feeders so that migratory hummingbirds aren’t deterred from leaving but even then, the animals have a almost perfectly developed internal migration clock but also they know to follow wherever the flower populations are high.
MY husband has the role of replenishing feed to three feeders on our property, only one easily accessible, the others a few yards into our wooded areas. Because of my age and infirmities (back) he must perform these chores.
As he, also has aged, his bedtimes have crept up to 6:30 in the evening when he must bring the feeders in for the night to avoid destruction by raccoons and deer. This concerns me, as this is the middle of one of the birds two principle feeding times. Fortunately, he is up at 5:30 to hang them up again after filling them. He is unconcerned about possible diminution of the “usual subjects” at the feeders because of this practice of removal of the feeders at night.
Please give me fuel for this on-going argument OR tell me that his position is doing no harm to our immediate bird population or long-term census. Thank you!
Hi Judith,
Removing the feeders in the early evening will not harm your birds and it is a good practice to deter raccoons and other animals. Birds are very resourceful and will be able to find another food source.
I have been feeding the birds because I have felt they needed my extra support. With all the construction isnt it obvious all the wildlife needs our help. I am lucky that I can do it as much as I do. It is expensive but it is my little way of helping the species continue. This year with the drought in the NE I have been adding daily water refills to my chores as well. I believe they know who cares I just hope I can continue to keep it up. Increase in yellow finches, blue jays, and sparrows numbers as well as starlings…it is hard not to shooo these guys away as they show up in large numbers.
Birder in Bristol CT.
This article does not address the many other species, and humans, that are impacted when every other house on the street has multiple bird feeders, especially for year-round feeding. For example, bird feeders are the number one draw of bears, who learn to search for these handouts, and this sometimes leads to them becoming “problem” bear that can become aggressive and have to be relocated or euthanized. Raccoons, squirrels, mice, rats, coyote, skunks, and other “nuisance” animals are attracted to either the seeds or to the prey that is drawn in. The populations of those species can be inflated, which can affect other species in turn, including humans. Squirrels eat bird eggs, for example. Coyote snack on small dogs. Mice and chipmunks carry ticks that harbor Lyme Disease. Raccoons break into attics, and humans have them exterminated. When the quantity of bird feeding is so high, the ripple effect goes far beyond the birds who actually visit the bird feeders. Finally, the vast acreage devoted to raising bird seed would be better off growing food for humans or left to revert back to nature, where it can serve as habitat for wildlife.
Hi Teresa,
You bring up some valid points. This article is just a snippet of on-going research that was presented at a recent conference. The research is focused solely on the impacts of supplemental feeding on bird populations. FeederWatch does discourage people from feeding birds while bears are active.
We have many deer and some bears in our area, and our birdfeeder is on top of our deck which is over 6 feet off the ground with steps leading up. It is also a squirrel proof feeder so even if a bear did get on the deck, it could not get into the feeder. We have seen three dead birds on our property in the last year, but only one was near the feeder, and none were damaged in a way to indicate a predator got to them.
Having had birdfeeders not elevated in the past, it seems that up on a deck is much better. A bonus is that our deck is not new, and woodpeckers not only use the birdfeeder occasionally, they also get bugs out of the railings and decking!
I’m glad to hear from you that bears are not getting on your deck and that your bird feeder is squirrel-proof. However, as an eight-year resident of Big Canoe, a large gated mountain/woodland community 60 miles north of
Atlanta and officially designated as an Audubon Wildlife Sanctuary, I feel I must caution you regarding over-confidence in your described deterrents of wild bears. Black bears are abundant members of the protected wildlife population in Big Canoe (8,600 acres and over 100 miles of paved roads) and storied experiences with them by human residents (over 2,000) are reported by the dozens annually. Bear-human encounters occur, probably daily, as long as the bears are not in hibernation.
Let me emphasize, at this point, I am not suggesting that you should be afraid of wild bears. Despite large numbers of the human/bruin populations, during our eight years of residence we never heard of an incidence of a bear injuring a human which, considering the strong sense of community, we certainly would have.
Now, to your wooden deck, six feet above the ground and the squirrel-proof feeder. Unless your deck is completely supported by steel poles/posts and tucked under a significant over-hang, six feet offers zero deterrence to a hungry, or even curious, bear. Our decks, 18 feet above ground, were supported by 6″by6′ steel posts, and our feeders were hung from a trolley on a 30′ wire strung from one of our decks to a nearby tree, making them squirrel-proof as well. Furthermore, unless your squirrel feeder is made of cast iron it is highly unlikely to survive an assault by the powerful teeth and claws of a bear, even if it is constructed of sheet metal, as are commonly available squirrel feeders. Black bears are immensely powerful, and can usually tear apart any non-bear-proof container the contents of which they wish to examine
So don’t be surprised, or afraid, if some day you look out and see a big, black, furry, animal contentedly munching sunflower seeds from the remains of a squirrel-proof feeder. BTW I have photos of black bears on the decks of good Big Canoe neighbors on their wooden-supported decks 20′ above the ground, the cutest of which is of a very large sow watching her three cubs, each separately munching bird seed from one of three tube feeders, hanging from steel hooks, set about 6′ apart, from the deck railing! Adult bears and maturing cubs are not deterred in the by a height of 20 feet.
Best wishes with your bird feeding, and be cautious, but not deterred by this message.
Feeders cause smaller mammals and rodents to be ambushed. Not dissimilar to the LA Tar Pits. So while you think you are helping, some poor creatures bear the brunt. I still fill my 5 bird feeders daily, but I do feel bad for the poor hungry souls that think they found food and are subsequently ambushed.
My hubby and I have been feeding various birds for numerous years.
My feeling is that the journey they make to migrate for the winter months is that this food provides them with some endurance to help along there way. ( hummers Orioles wrens etc)
The others that stay year round are likely over fed at times from all of us who enjoy the bird feeders. We provide for the squirrels and chipmunks also.
We’ve had many pleasurable hours of watching these birds and animals.
This post is headlined as “highlights” from the presentation. If this is true then it would seem that the most serious concerns about the negative effects of bird feeding have not been addressed at all. Badly managed feeders (and that would include almost every feeder I’ve ever seen) are partly responsible for increased populations of “subsidized predators”. To consider only those bird species that directly benefit from the food presented at the feeders is missing the point entirely. I am really surprised by this failure to address the much more significant indirect threat. Really surprised – and disappointed.
Thank you for bringing up these valid points. This article is just a snippet of on-going research that was presented at a recent conference. The analysis was focused solely on the direct impacts of feeding on species that use feeders the most. We hope to address indirect effects on migratory species and subsidized predators in future work. It is impossible to address every question with a single analysis, and research as complex as the impacts of feeding birds requires many stages of work.
As an anecdotal response, I’ve been operating bird feeders of various kinds for over 40 years, from very rural areas in both Maryland and Massachusetts to my present urban situation. In the first situation, we had quite an extensive clan of outdoor cats that lived with us, and apart from an old tom who liked to sit on the platform feeder waiting for a bird to fly into his mouth (none ever did), I saw no evidence of cat predation on birds. I’m confident it happened, just that I never saw any evidence that it did. On the other hand, I frequently saw evidence of cat predation on small mammals and reptiles. Here in the city, we have had regular visits by both Cooper’s and Sharp-shinned hawks, as well as cats. The hawks occasionally make a kill, as shown by the feather pile and leftovers, but most of their attacks, no matter how persistent, come up empty. The cats I have never seen make a bird kill, although they have killed mice and the occasional rat. Again, this doesn’t mean it doesn’t happen; just that I haven’t seen any evidence of it. The feeders have drawn, over the years, a pretty good array of birds to what I would have expected to be more or less a desert. The predators might be having an effect, but I suspect it’s not a large one; it’s my opinion that the toll on birds during the breeding season far outstrips the toll during the feeder season. In any event, when it comes to hawks, my attitude is that if you feed the birds, you feed _all_ the birds.
All animals adapt to change ; the food provided to them by people who provide it can only help them thrive ! At my house the bluejays actually ask for peanuts !
Our cat dish is popular with the crows and blue jays. It also attracts possums and box turtles that we know of, likely raccoons, and possibly a coyote, judging from the volume that can disappear overnight.
Our outside cat has not shown any interest in birds that we have seen. The wrens sound the alarm for him all summer though, so likely he has picked off some fledglings.
We have hummingbirds that return, as evidenced by their searching for food where we had a feeder hung the year before. I can’t help but think this is supporting their chances of survival.
Peace be with you; Incorporate plants natural to their food sources in the wild. Shanah Tovah Bird brains, saved baby Blue Jay a couple weeks short of flight this year; brought to Wings Rehab in Amherstburg, Ontario, God bless you…in name of Jesus Christ, thanks praise glory to God, amen.
What I know for sure is ever since I started feeding the birds my CARDINAL POPULATION has MORE THAN QUINTUPLED!!!!!!
Have a couple of feeders – near a tree and another near bushes. Have enjoyed watching the regular neighborhood birds visit and fly from feeder to feeder. I do know it helps-especially in the frigid winter when I see them eating in a frenzy, unable to find other food sources. When the weather is warmer-the feeders are frequented less often as the birds are foraging elsewhere. They control the insect population as well. We don’t have bears in the area but do have deer, squirrels, and other usual nocturnal animals. Haven’t had one problem with them. Think it’s important to keep the feeders and area clean, and food off the ground. Bottom line-I do think it helps this animal class-especially when food is hard to come by.
Feeding birds is the least I can do.
I’ve been maintaining a couple of bird feeders for the past two years and watching the little guys gives me great joy. So, it’s encouraging to know that at least my habit is not affecting negatively the birds. My experience is similar to some of the voices here in that I see a large increase in numbers of birds feeding during the harshest days of winter and a lighter presence when the weather is more pleasant outside.
Additionally I see these feeders as a small contribution I make to other life forms on this beautiful planet. As a species we seem to have taken earth to be ours for our consumption rather then a shared home with multiple life forms who play an integral role and are essential to the health of our environment. But this would require another article so thanks for this space to share our love and appreciation of birds.
’ve been maintaining a couple of bird feeders for the past two years and watching the little guys gives me great joy. So, it’s encouraging to know that at least my habit is not affecting negatively the birds.
Feeding birds is the least I can do.
I’ve been maintaining a couple of bird feeders for the past two years and watching the little guys gives me great joy. So, it’s encouraging to know that at least my habit is not affecting negatively the birds. My experience is similar to some of the voices here in that I see a large increase in numbers of birds feeding during the harshest days of winter and a lighter presence when the weather is more pleasant outside.
I have read through the comments, to date. There are 4 feeders clamped onto my fence ramp, and a hanging water feeder, and a bird bath in my front and back area. I have considered them supplemental feeding in the spring to autumn, and perhaps more useful in the winter. Being a transplanted Ohioan, Virginia, in most of the state, does not experience winters of snow as much as rain. I think the water is more important, so hanging waterers, baths and ground bowls fill my lot. There has been an increase in the dawn chorus and the bird population is more evident. I also track the flight of birds away from the feeders, and it appears they are coming from trees a distance away. Raccoons come by rarely. Possums have been feeding in my yard for seven years. This morning I saw a bunny in the common walkway, which has a good array of trees and shrubs. Of my three cats, only one goes after squirrels, the possums fascinate them, and the birds are not available. One cat goes out after dusk. All the concerns posted I have had. I suppose humans will continue to have a fascination with wild creatures, and most of our behaviors are good – rescue, rehabilitation, return. Reverence for them may be what compels us this behavior.
Although our community frowns on us using feeders, I have been doing so for years. I keep a large saucer on the rail and enjoy the cardinal family, nuthatches, titmouse, sparrows, Goldfinch, doves and Bluejays. The Bluejays and crows come in the morning to receive a handful of peanuts, although they have to fight with the squirrels. This season i noticed an abundance in breeding and witnessed multiple clutches. I attribute it to a lengthy spring-summer, as well as a food source and birdbath. Unfortunately, the squirrels had an abundant breeding too and are snatching a lot from the birds when i am not chasing them. I’ve never had this many squirrels. I am concerned, however, as we will be moving out of state in January when they need nourishment most. The birds readily recognize me and follow me to see if food will be made available. My concern is that the loss of a consistent food source my cause harm to my feathered friends. It would be interesting to be able to determine if the loss of resources results in a decrease of breeding in the future.
Does the supplemental feeding of birds from a bird feeder during the nesting season have an adverse effect on parents teaching young how to obtain food such as invertebrates?
Hi Susannah, Supplemental feeding is just that – supplemental. Birds get food mainly from their natural environment and supplement it by occasionally stopping at feeders, so the adults are still quite adept at showing their young how to obtain food. By winter, the birds may start visiting feeders more often as natural supplies wane, but by that point juvenile birds are fully independent. I am not aware of any studies showing feeders having an affect on how young learn to feed themselves.
I thought I had one female downy woodpecker this winter. But yesterday, there were two females and a male downy at the suet ALL at the same time ! I felt as though I had won the lottery. This is February 28, 2023 and while outside I saw and heard the first flock of geese fly over. It looked like a mix of Canadians and snow geese. I live in Nebraska just a few miles from Lincoln – in a small town. I also put a sliced apple out each night for the raccoons. However, I have not told my neighbors or management as I am certain that would get me in Hot Water.