Bird deaths by human agency

Large risks to birds are sometimes attributed to wind turbines, so I bring together some annual estimates, specific to US. It there is interest these could be shored up with actual research citations.

Total number US birds: 10 to 20 billion (that’s a lot of tweets).

Free-ranging domestic cats kill 1.3 to 4.0 billion birds per year

Building crashes kill as many as 970 million birds annually (windows should be decorated!).

175 million birds die by flying into power lines or at those towers.

Legal hunting exceeds 100 million.

72 million are poisoned by misapplied pesticides.

Vehicle collisions: 50 to 100 million.

Communication towers bird deaths: 4 to 10 million

Oil and gas industry fluid waste pits: as many as 1 million birds

Hay cutting 1 million (listen better, little birdies).

Land-based wind turbines killed as many as 573,000 birds in 2012. Furthermore, by 2030 or before, a 10-fold increase in turbines is expected to boost annual bird mortality to 1.4 to 2 million.


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Those wind-turbine fatalities include estimated 83,000 raptor (large predatory bird) fatalities, which are often emphasized. I cannot find source for this estimate. Other sources indicate raptors are from 3 to 15% of wind-turbine bird kills, which would extrapolate to 19,000 to 86,000. Raptors (including owls) were 59% of bird fatalities at California’s famous Altamont Pass, but wind turbines are not being built like that anymore. Another way to approach this would be with estimated 0.033 raptors killed per turbine per year, multiplied by number of turbines. Turbine fleet of 60,000 works out to 2000 raptors.

Before continuing, need to take a shot at estimating raptor populations. Very difficult (especially as Wikipedia has disappeared here). I’ll say 4 million in total, dominated by hawks, vultures and owls. Perhaps 50,000 eagles (golden and bald). Kinda fluffing on eagle populations in Alaska, but they are not at risk for causes mentioned below (except perhaps poisoning).

Power lines and towers 1 kill million raptors per year??? This is a very uncertain estimate based on extrapolation from small-scale studies. There have been strong efforts to design equipment to minimize risks to large birds, and it is thought to have lowered fatality rates. If total raptor population is about 4 million, this 1 million estimate seems very unlikely. Big birds do not reproduce rapidly enough to keep up with that.

Except for burrowing owls, one would suppose feral cats eat few raptors (more likely the converse!). Perhaps some chicks fall and end that way, but they’d probably be doomed even in a cat-free world.

There is little legal hunting of raptors in US (you can get a vulture permit).

Raptors apparently are only a small fraction of building crashes.

Raptor fraction in vehicle-collision studies range from “none” to “most”.

Indirect poisoning from rat poison or lead shot is a risk unique to raptors (including carrion feeders). I find no mortality estimates here either, but high (>50%) proportions of sick raptors taken to ‘sick-bird places’ have dangerous blood levels of rodenticides or lead.

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Summary.

For birds in general, wind turbines are far down the list of killers.

For raptors it is very difficult to know, because no cause of death is adequately measured. If this is something people want to know, studies could be supported. In absence of defensible all-cause estimates, it makes no sense to claim wind turbines are the largest.

Any guessing that I'd be in favor of studies to place raptor/turbine deaths into a quantitative framework would be correct.

 

Australia begins a large program for feral cat removal:

Australia Declares War on Feral Cats | KTLA

 

There are feral-cat control programs elsewhere that could be mentioned. Actually a global examination of this could have much merit. More than birds are on the menu...

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I will give sources for oil-pond numbers. Please allow some time for me to find the best work. I suppose such ponds are all subject to direct observation, and that bird mishaps do not quickly disappear. For those reason, observational data is probably more accurate there than at cell towers, power lines, or wind turbines.

External to US focus, Alberta oil sand activities seem to 'collect' a lot of birds. But making this a global discussion would take a lot of effort.

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Have suggested before that stilling wind turbines as bird migrations pass through could avoid some Cuisinart (TM) action. I know that happens in Israel but ??? anywhere else.

 

Strong dominance of cats as de-birding agents suggests that even incomplete efforts at cat population control could have substantial leverage.

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Mostly separate from topic here, cats in the bird food chain can move bird diseases around. All cat predators can do that, but only indoor/outdoor cats vector the goodies back to you.

Completely separate from topic here, cats taking rabid bats are serious things.

 

Unleash the betas@10. I know of no information on that subject. My eco-sense is that it should matter more for species with hierarchical clan structure. Coyotes and kitties being polar opposites in that regard.

Genetic sequencing from hair and feces is getting very inexpensive. Should be feasible to sample an area (where cats are important predators) and find out who's boinking whom. Then trap out a selection of cats and see how population responds.

 

Airport cats@12. If it's effective and if bird-control companies are not doing it. That would be strange.

A new career for bisco...

 

I like birds also. They have an array of 'natural' predators and it's difficult to gripe about that. But human population increase has altered the landscape. Both in literal and metaphorical senses. That's just the way things are eh?

But in many areas of human agency, effects on bird populations can be dialed down without sacrificing civilization's goodies. This is why we talk about cat population control, decorating big glass windows, increasing spacing between power line 'phases', controlling release of rat poison and lead pellets to the environment. And even painting wind-turbine blades funny colors so those birdbrains notice.

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I omitted an 'elephant' from this room initially. It is habitat modification, and birds including migratory ones notice

That situation will not be undone, but bird boxes and other bandaids can help a little. Bird feeders are a perplexing subject though. Unusually high bird and poop density seems to promote disease transmission at least in some cases.