As you can see, not a lot of open space, but we do have front and back yards with trees.
I’ve been running a bird feeder for years and I’ve always wondered about my effect on the local bird population. I have no idea how dependent the local population is on my feeder.
According to the EPA, it takes about 11.4 lbs of feed to produce a 6lb chicken and I feed my guys about 10lbs a week, so how many pounds of tweety birds am I keeping alive?
Is food even the main limiting factor? I imagine nesting sites are limited and there have to be predators as well. So are populations up and down the food chain stable after all these years and nothing really changes much or can one backyard feeder have a real impact?
The ability to fly combined with very good vision means birds are very good at finding food. One backyard feeder won’t have much, if any, effect on the general population. Basically, bird feeders are for people, not for birds.
You’re on to something with your thoughts on nesting sites. Bird houses are for birds, not for people. Some invasive species, House Sparrows (HOSP) and European Starlings in particular, can cause a severe shortage of nesting sites for native species.
If you are feeding sparrows and starlings you will have a lot of birds but they will be those invasive species, not the native species. Putting up bird houses and allowing them to be occupied by invasion species is likely worse for the native population than not putting up nest boxes at all because the invasive species breed so quickly.
It is possible to have a small sanctuary for native birds. For example, in some areas the sparrows don’t eat safflower seeds, so filling the feeder with those may keep the sparrows away. Putting up a bird house from a big box store likely means it will be used by invasive species – by doing some research, you can find a bird house with the proper size to allow, for instance, native chickadees while excluding HOSP.
It gets complicated. If you enjoy watching whatever birds come to your feeder, that’s fine. If you have an interest in helping the native bird population in your area, you can do some research on how to go about it.
In the past several years I have noticed a marked decrease in the population of sparrows and a marked increase in the native birds many of which are now common but previously never seen by me in this area. We were almost overrun with startlings 20 years ago and now they are somewhat common but not at all what I would consider a pest levels anymore. I credit the crows and ravens with this.
Some other issues you might want to take into consideration:
Your feeders, a reliable source of high-value food for small seed-eating birds, also becomes a reliable source of food for bird predators. Your neighbourhood Coopers hawks probably are well-aware of your feeders. Birds feeding on natural food won’t be as affected by this locally-intensified predation.
Bird feeders may be a source of disease. Obviously, these dangers can be mitigated with good practices, like maintaining hygienic supplies of seed, washing the feeders thoroughly, cleaning up droppings, etc. The SF Bay Area has recently had an outbreak of Salmonellosis, and local agencies have recommended removing bird feeders temporarily.
Stress. If your feeders are very popular, competition between the birds for the resources causes higher cortisol and other stress hormone levels. And stressed birds are more likely to succumb to disease.
Interestingly, participation in feeding wild birds is influenced by culture. In some places (e.g., Australia) the prevailing attitude is of non-interference, and that any human intervention (especially providing food) is unnatural and potentially damaging.
Your feeders, a reliable source of high-value food for small seed-eating birds, also becomes a reliable source of food for bird predators. Your neighbourhood Coopers hawks probably are well-aware of your feeders.
I have one feeder, under an eve, 8 inches from a wall on one side and 24 inches from 10ft high bushes on another. The birds hang out in the bushes and hop over to the feeder or down to the ground when they feel like it.
I’ve actually seen hawks pick birds off of feeders before and they prefer high speed attacks where they can swoop in and grab quick. The positioning of this feeder is too tight for hawks; I’m sure they have better spots.
- Bird feeders may be a source of disease.
Meh. The birds themselves may be a source of disease. The feeder is glass and anodized aluminum and gets cleaned regularly.
- Stress. If your feeders are very popular, competition between the birds for the resources causes higher cortisol and other stress hormone levels. And stressed birds are more likely to succumb to disease.
My feeder gets action twice a day for roughly an hour at a time in the morning and afternoon. The rest of the time, there may be an occasion hit now and then, but it mostly sits quietly. I think it is just as likely that I’m relieving the stress of competition for extremely limited natural resources.
I’m curious how much of the diet of “city” birds comes from feeders like mine, is there any scientific literature on that you can point me to? I’m not talking pigeons… never seen one at my feeder, but I do have the occasional morning dove on the ground below the feeder.
The figure of 20% of wild bird diet from feeders is bandied about a fair bit, which I think comes from the following 1992 paper: The Use of Winter Bird Feeders by Black-Capped Chickadees. (Behind a paywall, sorry - couldn’t find a free to access copy, but you can read the abstract here).
As Turble says, feeders are for people. If you really want to have a positive impact on wild native bird populations, you could look into having your backyard certified as a wildlife habitat.