Guest Post by Jim Steele
What’s Natural
In 2019 bird researchers published Rosenberg et al “Decline of the North American Avifauna”, reporting a decline in 57% of the bird species. They estimated a net loss of nearly 2.9 billion birds since 1970, and urged us to remedy the threats, claiming all were “exacerbated by climate change”, and we must stave off the “potential collapse of the continental avifauna.” Months before publication the researchers had organize and extensive media campaign. Typical doomsday media like the New York Times piled on with “Birds Are Vanishing From North America” and Scientific American wrote, “Silent Skies: Billions of North American Birds Have Vanished.”
As I have now been sheltering in place, I finally had ample time to thoroughly peruse Rosenberg’s study. I had a very personal interest in it, having professionally studied bird populations for over 20 years and had worked to restore their habitat. I also had conducted 20 years of surveys which were part of the study’s database. Carefully looking at their data, a far more optimistic perspective is needed. So here I join a chorus of other ecologists, as reported in Slate, that “There Is No Impending Bird Apocalypse”. As one ecologist wrote, it’s “not what’s really happening. I think it hurts the credibility of scientists.”
First consider since 1970 many species previously considered endangered such as pelicans, bald eagle, peregrine falcon, trumpeter swan, and whooping crane have been increasing due to enlightened management. Despite being hunted, ducks and geese increased by 54%. Secondly, just 12 of the 303 declining species account for the loss of 1.4 billion birds, and counterintuitively their decline is not worrisome.
Three introduced species – house sparrows, starlings and pigeons – account for nearly one half billion lost birds. These birds were pre-adapted to human habitat and are considered pests that carry disease and tarnish buildings and cars with their droppings. Across America, companies like Bird-B-Gone are hired to remove these foreign bird pests. Furthermore, starlings compete with native birds like bluebirds and flickers for nesting cavities, contributing to native bird declines. The removal of starlings is not an omen of an “avifauna collapse”, but good news for native birds.
When European colonists cleared forests to create pastures and farmland or provide wood for heating, open-habitat species “unnaturally” increased. Previously confined to the Great Plains, brown‑headed cowbirds quickly invaded the newly opened habitat. Unfortunately, cowbirds parasitize other species by laying its eggs in their nests. A cowbird hatchling then pushes out all other nestlings, killing the parasitized species’ next generation. The loss of 40 million cowbirds only benefits our “continental avifauna”.
Several bird species had evolved to colonize forest openings naturally produced by fire, or floods or high winds. Those species “unnaturally” boomed when 50% to 80% of northeastern United States became de-forested by 1900. Still, eastern trees will reclaim a forest opening within 20 years, so open habitat species require a constant supply of forest openings. However as marginal farms and pastures were abandoned, fires were suppressed and logging reduced, forests increasingly reclaimed those openings. With a 50% decline in forest openings, their bird species also declined; now approaching pre-colonial numbers. Accordingly, birds of the expanding forest interior like woodpeckers are now increasing.
White-throated Sparrows and Dark-eyed Juncos quickly colonize forest openings but then disappear within a few years as the forest recovers. Those 2 species alone accounted for the loss of another quarter of a billion birds; not because of an ecosystem collapse, but because forests were reclaiming human altered habitat. Nonetheless those species are still 400 million strong, and juncos remain abundant in the open habitat maintained by suburban back yards. If environmentalists want to reclaim the abundance of their boom years, they must manage forest openings with logging or prescribed burns.
Insect outbreaks also create forest openings. For hundreds of years forests across Canada and northeastern US have been decimated every few decades by spruce bud worm eruptions. So, forest managers now spray to limit further outbreaks. Today there are an estimated 111 million living Tennessee Warblers that have specialized to feed on spruce bud worms. But the warbler’s numbers have declined by 80 million because insect outbreaks are more controlled. Still they have never been threatened with extinction. Conservationists must determine what is a reasonable warbler abundance while still protecting forests from devastating insect infestations.
The grassland biome accounted for the greatest declines, about 700 million birds. Indeed, natural grasslands had been greatly reduced by centuries of expanding agriculture and grazing. But in recent times more efficient agriculture has allowed more land to revert to “natural” states. However fossil fuel fears reversed that trend. In 2005 federal fuel policies began instituting subsidies to encourage biofuel production. As a result, 17 million more acres of grassland have been converted to corn fields for ethanol since 2006.
Although still very abundant, just 3 species account for the loss of 400 million grassland birds: Horned Larks, Savannah Sparrows and Grasshopper Sparrows. Horned Larks alone accounted for 182 million fewer birds due to a loss of very short grass habitats with some bare ground. To increase their numbers, studies show more grazing, mowing or burning will increase their preferred habitat.
It must be emphasized that the reported cumulative loss of 2.9 billion birds since 1970, does not signify ecosystem collapses. But there are some legitimate concerns such as maintaining wetlands. And there are some serious human-caused problems we need to remedy to increase struggling bird populations. It is estimated that cats kill between 1 to 3 billion birds each year. Up to 1 billion birds each year die by crashing into the illusions created by window reflections. Collisions with cars and trucks likely kill 89 to 350 million birds a year. Instead of fearmongering ecosystem collapse, our avifauna would best be served by addressing those problems.
Questioning Bird Models
Population estimates for most land birds are based on data from the US Geological Surveys Breeding Bird Surveys (BBS). I conducted 2 BBS surveys on the Tahoe National Forest for 20 years. Each survey route consists of 50 stops, each a half‑mile apart. At each stop for a period of just 3 minutes, I would record all observed birds, the overwhelming majority of which are heard but not seen. Many birds can be missed in such a short time, but the BBS designers decided a 3-minute observation time allowed the day’s survey to cover more habitat. Each year on about the same date, the BBS survey was repeated.
Each BBS route surveys perhaps 1% the region’s landscape. To estimate each species’ population for the whole region, the survey’s observations are extrapolated and modeled. However, models rely on several assumptions and adjustments, and those assumptions that can inflate final estimates. For example, in 2004 researchers estimated there were 6,500,000 Rufous Hummingbirds. By 2017, researchers estimated there were now 21,690,000. But that larger population cannot be deemed a conservation success. That tripling of abundance was mostly due to new adjustments.
Because singing males account for most observations, the number of observed birds is doubled to account for an unobserved female that is most likely nearby. Furthermore, it is assumed different species are more readily detected than others. The models assume that each stop will account for all the birds within a 400‑meter radius. Because a crow is readily detected over that distance, no adjustments are made to the number of observed crows. But hummingbirds are not so easily detected. The earlier surveys assumed a hummingbird could only be detected if it was within an 80‑meter radius. So, to standardize the observations to an area with a 400‑meter radius, observations were multiplied by 25. Recent survey models now assume hummingbirds can only be detected within 50 meters, so their observations are now adjusted by multiplying by 64.
Thus, depending on their detection adjustments, one real observation could generate 50 or 128 virtual hummingbirds. That number is further scaled up to account for the time‑of‑day effects and the likely number of birds in the region’s un-surveyed landscapes.
Setting aside assumptions about the regional homogeneity of birds’ habitat, one very real problem with these adjustments that has yet to be addressed. If one bird is no longer observed at a roadside stop, the model assumes that the other 127 virtual birds also died.
Survey routes are done along roadsides and up to 340 million birds are killed by vehicles each year. Many sparrows and warblers are ground nesters and will fly low to the ground. Many seed eating birds like finches will congregate along a roadside to ingest the small gravel needed to internally grind their seeds. Every year I watched a small flock of Evening Grosbeaks ingesting gravel from the shoulder of a country road, get picked off one by one by passing cars. Roadside vegetation often differs from off-road vegetation. Roads initially create openings that are suitable for one species but are gradually grown over during the lifetime of a survey to become unsuitable habitat. So, it should never be assumed that the loss of roadside observations represents a decline for the whole region.
The larger the models’ detectability adjustments are for a given species, the greater the probability that any declining trend in roadside observations will exaggerate a species population loss for the region. The greatest population losses were modeled for warblers and sparrows and most warbler and sparrow data are adjusted for detectability by multiplying actual observations 4 to 10-fold. It is worth reporting good news from recent studies in National Parks that used a much greater density of observation points and were not confined to roadsides. Their observation points were also much closer together and thus required fewer assumptions and adjustments. Of the 50 species they observed, all but 3 populations were stable.
Pushing a fake crisis, Rosenberg et al argued that declining numbers within a species that is still still very abundant doesn’t mean they are not threatened with a quick collapse. He highlighted the Passenger Pigeon was once one of the most abundant birds in North America and they quickly went extinct by 1914. That doomsday scenario was often repeated by the media. But comparison to the Passenger Pigeon’s demise is a false equivalency. Passenger Pigeons were hunted for food when people were suffering from much greater food insecurity.
Rosenberg et al summarized their study with one sentence: “Cumulative loss of nearly three billion birds since 1970, across most North American biomes, signals a pervasive and ongoing avifaunal crisis.” But it signals no such thing. Wise management will continue. With better accounting of the natural causes of each species declines, plus more accurate modeling, it will be seen that Rosenberg’s “crisis” was just another misleading apocalyptic story that further erodes public trust in us honest environmental scientists.
Jim Steele is director emeritus of the Sierra Nevada Field Campus, SFSU and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism.
Contact: naturalclimatechange@earthlink.net
Jim
This is in no way a criticism of you or what you have written. I very much appreciate your contrarian views of things that are usually taken for granted.
As is so often the case when considering problems associated with the impact of Man, there are unstated assumptions that lean heavily towards blaming humans, even before a study is conducted. What I’m suggesting is that there is a tendency to have a myopic view of the situation and focus on one aspect, in this case, the impact of cats on birds, and to ignore the bigger picture. To whit, feral cats and strays often become food for larger predators such as foxes, coyotes, owls, and eagles; cats become alternative food for competitors. At the same time, cats reduce the availability of food for the larger predators. In the absence of cats, one could expect that the smaller birds, rodents, and reptiles would increase, providing more food for foxes, bobcats, hawks, and coyotes. With more food, their offspring will have higher survival rates, and put more pressure on small prey. It is a dynamic system in which various predators can fill the role of others. That is, I haven’t seen evidence that if cats were removed from the picture that the same number of birds wouldn’t be killed by the ‘natural’ predators that pre-dated the introduction of domesticated cats. The question becomes, are feral cats more efficient predators than native predators? If yes, then they are having a negative impact on birds. If the predation efficiency of cats is comparable to other similar-sized predators, then it is problematic that they are having an excessive impact. To the extent that cats are reducing the population of small prey, and hence food for competitors, then they are also reducing the population of competitors. Clearly, cats have an impact on the balance between prey and predators. However, it becomes a value judgement as to whether a weasel or skunk has higher ‘value’ than a common cat. Nature is pretty good at balancing out things. If cats were the deadly killers they are made out to be, by those who place high value on birds, then Europe and Asia would long ago have seen extinctions of those birds that were common prey of Felis sylvestris.
The house mouse is thought to have originated in Asia. It then almost certainly was introduced to the New World by explorers and immigrants from Europe. It is a major food source for feral and domesticated cats. Would we eliminate cats and ignore the non-native mice, rats, starlings and other small prey? Pandora’s Box was opened by early Man. I think it a fools errand to try to put everything back in.
Consider this aspect, Clyde: A pair of songbirds lays between four and ten eggs per clutch, occasionally more, and has three to four clutches per year in many locales.
Then each of those start breeding after not too long.
But for the number of songbirds to remain stable, exactly two birds from each pair, and all of the descendants thereof, have to survive the original pair, which may live ten to twelve years or more.
That is a lot of offspring, the overwhelming majority of which will necessarily die or the populations will explode.
Two more than that number surviving per year will cause a population to double every year.
NIcholas, Most migratory warblers only produce one clutch and typically lay about 4 eggs on average. Some resident sparrows like the juncos often have 2 and maybe 3 clutches, but that depends on the local climate Again they lay about 4 eggs.
Ducks and quails will lay up to 10 eggs, but 10 is unheard of more virtuallhy every songbird.
Hey Jim,
I confess I have never gone up any trees to check, but I have double checked sources from my library to Wikipedia, that detail hole nesting species like tits commonly laying as many as 12 per clutch, and sometimes way more than that.
These numbers always surprise me too, and I have studied birds since I was in grade school.
“Most tree-nesting tits excavate their nests, and clutch sizes are generally large for altricial birds, ranging from usually two eggs in the rufous-vented tit of the Himalayas to as many as 10 to 14 in the blue tit of Europe. In favourable conditions, this species had laid as many as 19 eggs, which is the largest clutch of any altricial bird. Most tits are multibrooded, a necessary strategy to cope with either the harsh winters in which they reside in the Holarctic or the extremely erratic conditions of tropical Africa”
Corvids are listed as having between 3 and 10 per clutch:
“Corvids can lay between 3 and 10 eggs, typically ranging between 4 and 7. The eggs are usually greenish in colour with brown blotches. Once hatched, the young remain in the nests for up to 6–10 weeks depending on the species”
I may be imprecise to use the term songbird to describe basically any small birds that come and feed at bird feeders.
I never make stuff up, and if I am guessing, I do my best to always remember to say so.
But when it comes to something like this, where I am refuting something in no uncertain terms, I always make sure I only say anything in a declarative way if I believe it is beyond contention.
Large clutch sizes may be uncommon, but from everything I have been able to gather about these kind of birds, they are mostly only food and daylight limited when it comes to breeding.
So if there is predation, more food will be available, more eggs can be laid by well fed females, more chicks fledged by prosperous parents.
I am not sure how soon after fledging various sorts of birds might have young or their own, but given the lifespan and the numerous clutches and the large number…even if it is four fledglings twice a year, that number will lead to a lot of birds from just two after a few years.
If I post links to the Wikipedia articles, the comment will go to moderation, but I did look at the references for these numbers, knew it to begin with from books right here on my shelves, and looked at other sites as well.
Hey, check out this video I came across today…a bird in Australia that imitates construction sounds…chain saw, hammer, drill, screw gun…and even the guy working the tools talking and laughing:
https://youtu.be/C0ZffIh0-NA
Nicholas, I am not saying you are “making up stuff”, I am saying I believe you are overstating the number of eggs and clutches that MOST birds produce. I confess not knowing anything about the European Great Tit and I was totally unaware of how many eggs they lay, although I do wonder if the high counts are due to brood parasitism. But Great Tits are an extreme exception for song birds.
Most migratory birds have only one clutch will re-nest under very favorable conditions or to replace a depredated nest. On average most song birds lay only 4 eggs. Some warblers that specialize on spruce bud worms will have larger clutches to take advantage of an insect outbreak, and I suspect the range of eggs laid by most species will depend on the amount of available food each year. I have done many nest searches but perhaps I am biased by Sierra Nevada birds but many of those species are widespread and I have yet to find a songbird with more than 6 eggs in a nest. Our song bird surveys also determined ratios of young birds to adults, and the data typically suggested on average about two surviving young for each breeding pair. No indication of large clutches producing greater ratios of young
Look at the linked paper “The Worldwide Variation in Avian Clutch Size across Species and Space”. They have a graphic showing the overwhelming number species lay only 3 to 4 eggs per clutch
https://journals.plos.org/plosbiology/article%3Fid%3D10.1371/journal.pbio.0060303
Nick
I was once hiking in a tributary canyon of the Grand Canyon and heard what I was sure was a dog barking. Wondering why there was a dog there, I followed the sound and, to my utter surprise found that it was a raven imitating a dog!
Clyde, I am not trying to suggest cats are inherently evil. I encouraged my workers to bring their cats to my field station to help alleviate our rodent problems (we were over run by deer mice- Peromyscus). But the cats did noticeably reduce other animals. And I do not see a bird’s death be it via a weasel or a cat as anything unnatural.
But I do worry that when people feed feral cats they are subsidizing their killing in a way that is now unnatural. A weasel’s survival will be limited by its hunting success, but a cat being fed by humans is not.
I do advocate eradicating introduced cats on islands ( as I advocate for foxes or mongooses) where their introductions have undeniably taken a toll and endangered many species that had not evolved a behavior to avoid land predators. But elsewhere I would take a local regional approach to determine if cats were helpful (eliminating rodents) or harmful.
Clyde ==> “If cats were the deadly killers they are made out to be, by those who place high value on birds, then Europe and Asia would long ago have seen extinctions of those birds that were common prey of Felis sylvestris.”
Can’t agree with you on that …
1) we don’t know that some species haven’t been driven to extinction by the domestic cat — it is certain that many ISLAND species have been wiped out by the combined pressure of domestic cats, pigs and dogs.
2) many bird species can far out breed the ability of cats to kill them. Not all birds are at risk from cats. Birds that nest in urban and suburban areas, and near human habitations with cats, on the ground or low in bushes and trees are the most adversely affected as the cats take the nestlings.
3) There is no doubt that cats kill birds — and there are some good studies on how many and which ones.
Cats, like all of our pets, should be confined to our homes or at least to our private property. We have no business allowing them to roam free in the environment.
Kip
I think that you missed the main point of my comment. Predators of similar size and similar diets are largely interchangeable in the ecosystem. Eliminating a particular predator, such as a cat, when there are many species of predators, means more food for the remaining competitors, and they will prosper, and eat the prey that the cats would have otherwise eaten. You are fooling yourself to think eliminating just one species will benefit the prey. There will always be a balance between the available food, albeit it that it might be cyclical. Jim makes an important point that feeding feral cats gives them an advantage over other predators and should not be done.
Certainly, the introduction of predators to islands that had never known mammalian predators will take a heavy toll on the defenseless prey. It is an entirely different situation disturbing an ecosystem with predators where there had been none. If I remember correctly, the breeding grounds of albatross are being impacted by rats that have made their way onto the island(s).
I would question the claim of “good studies” unless a complete inventory was done of ALL predators and the impact each has on the prey population. That would also include the cats being taken by larger predators, which then don’t have to turn to smaller prey that the cats would normally take.
I don’t imagine that most cats would be any happier with ‘lockdowns’ than most humans are these days. I once had a tomcat that had been hit by a car and lost an eye. I tried to keep him in so that he wouldn’t get injured in fights with other cats, or be taken by a dog. Despite having a litter box in the house, which he had always used faithfully, one day he urinated in an empty shoe box in my closet. I figured that he was expressing his displeasure with his confinement. I gave in and let him out. That was the only time he ever urinated in the house outside his litter box. Animals are intelligent and complex creatures. They need more than food and water and a place to sleep.
In many parts of the US, there are almost no small predators.
Without predation, populations outstrip the available resources.
Predation also generally eliminates the unfit, sick, old, stupid, and when there are just too many of something.
Anyone who has spent significant time observing cats and birds knows the circumstances wherein a cat might catch a bird. It is not healthy adults.
Unless perhaps someone sets up a situation that lures birds into an ambush.
But even then, the other birds will see what is happening and learn.
Even small songbirds can recognize a particular person who has acted in a threatening way, years later.
A study at a New England University demonstrated that certain corvids can not only recognize a particular person who was a threat, but can somehow communicate a particular face to individuals that never saw the person, who will then recognize the threat.
Cats are fast, but birds are faster, at least as smart, and they can fly.
But say that somehow cat haters succeeding in getting approval to round up all cats they did not feel like keeping and killed every last one of them.
What happens to vermin populations when all the cats are rounded up and slaughtered?
Why, in the minds of some individuals, are the lives of those animals to be counted for nothing unless they are detained as pets that must always be confined?
Even this study showed that back yard birds are not the ones declining…if anyone really knows one way or the other.
One thing I know…every place I have ever been in the eastern US, you walk outside in the morning, and birds are flying hither and yon and huge numbers.
Another thing I know is, cats are living beings, not toys or disposable plaything.
Clyde, yes, I was going to mention that for every bird I find that my 3 cats has killed (only rarely find a bird), I find 100 others, mostly mice & voles & an occasional mole, rat, rabbit & squirrel.
To all the cat lovers who take exception to the one reference to cats as a threat to birds. The article I referenced was based on the study Loss (2012) “The impact of free-ranging domestic cats
on wildlife of the United States”
found at https://www.nature.com/articles/ncomms2380.pdf
It was a meta-analysis.
They calculated there are about 1 billion owned cats and about 1.8 billion feral cats for a total of nearly 3 billion cats. If I assume that humans and cats displaced a substantial number of natural predators and not all cats are good hunters, I would estimate that there are about 1 billion cats exerting above natural pressure on bird abundance. I would suspect the more vulnerable birds are the ground nesters such as Juncos in the suburbs or meadowlarks around farmland. If we trust the BBS data, both species have declined significantly. If each of the 1 billion cats kills just 1 bird, then the low end estimate of a total loss of 1 billion birds due to cats is reasonable. I have not thoroughly perused the paper, nor checked the papers that they used to support their estimations. I will do so, and I suggest others do so as well.
Jim ==> You are spot on about free-roaming cats. It is just plain weird that our country ( USA) has strict laws about pet dogs and NONE about pet cats. I think people should have pet house cats — they make nice companions — particularly for old folks. People could be allowed to have outdoor cats if they owned enough property (so that the cats remain on their private land) or if they could keep the cats confined to their yard (not easy to do).
There should be no free-roaming cats in urban and suburban areas.
There might be an exception for “working cats” — such as those that live in and near dairy barns.
Feral cats — un-owned, free-roaming — should be rounded up and dealt with humanely — euthanized.
(I have a strong opinion on this, but have dialed it back for public consumption.)
We have a diabolical cat problem in Australia, both feral and domestic. We also have marsupial equivalents which are listed as threatened species (quolls).
Fewer cats and more quolls should make sense. However, cat ownership is simple and ubiquitous. Keeping a pet quoll is downright dangerous, it would seem, given the restrictions placed on this species in captivity reduces that possibility to a mere pipe dream.
Even a child rescuing frog’s eggs from a drying puddle and removing them to a garden pond for their own protection is strictly illegal. How this ‘saves’ a species is quite beyond me.
Kip
You remark, “It is just plain weird that our country ( USA) has strict laws about pet dogs and NONE about pet cats.” I think that there are two important distinctions. Dogs are more likely than cats to get rabies if they are not vaccinated, and dogs are more likely to bite people than are cats, if they are not confined or supervised.
You also opine, “There should be no free-roaming cats in urban and suburban areas.” I think that this betrays your bias. There are few if any ground-nesting birds in urban areas, and even manicured suburban areas provide poor habitat for birds that would be at risk from cats. Urban areas often attract rats, and would benefit from cats whether feral or domesticated. I don’t think that you are being objective about this, despite claiming to like cats.
I love birds and cats.
Rodents, roaches…not so much.
Cats kill hundreds of rodents and roaches for every bird they might get ahold of.
Typically it is when a nestling falls from a nest, or a nest is poorly located like in a rain gutter or a low branch.
I would not be surprised if raccoons kill more birds than cats.
And crows.
Owls and hawks typically clear out every songbird from the site of a bird feeder once or twice a year. Takes about a month for any of them to come back.
Cats mostly wish they could catch a bird.
“Feral cats — un-owned, free-roaming — should be rounded up and dealt with humanely — euthanized.”
This is appalling.
Truly.
Luckily we have laws to severely punish lunatics’ who try to murder small animals.
Anyone with a real interest in ecology must surely see that species rise and fall in response to a wide range of events, including many natural and/or cyclical events.
However, there is one sure method to find that a species is threatened by decline.
Don’t look for it.
Here, in Victoria, Australia, we have a cute threatened aboreal marsupial as a state emblem. Some environmental activists have defied Covid movement restrictions to search forests soon to be harvested, where they have found the cute millionaire possums (Leadbeaters), in residence, leading to an immediate logging ban (but, naturally, no findings leading to fines or convictions for breaking the law, largely as these locals and foreign visitors were all, like the cute possum itself, totally homeless)!
One may reasonably ask if it is so easy to find this cute endangered species in logging coups on demand, is it not possible to find them elsewhere?
These are surely “millionaire” possums, as the state government has effectively protected at least a million trees for each known individual of this cute small-framed nocturnal mammal species, which is clearly one or two more than they really need.
Whilst it is perfectly sensible to support legislation for the protection of an endangered species, the critical foundation of this must be sound population studying of said species. Too often, the protection comes first and the sound population studying comes never, even for famously cute state emblems.
For the record, I have followed current best practices by referring to the species as “cute” as often as I reasonably could. And then some. One couldn’t call oneself a conservationist if one didn’t.
.
I want to know how they counted those 2.9 billion birds. Armies of volunteers with clickers scouring the trees for birds? What’s that? They didn’t actually count all 2.9 billion, you say? Huh. Never mind. Nothing to see here. Moving on to the next imaginary apocalypse…
I was also wondering what proportion of total bird population this number represents?
In any case, most small and medium birds have numerous eggs, and many have more than one clutch per year.
Some thoughts on cats and one on birds:
-Cats do kill birds but I’ve only ever known one that was good at it and you would regularly see him hunting and catching healthy adult birds. Outside of that one cat I’ve seen a lot of cats try and fail, can’t say anything about how many nests they raid. While our house cats brought us all sorts of mice so we knew they were doing their job, they’ve only managed to bring us a couple of birds in decades worth of mouse gifts.
-There’s no way in hell you’ll be able to catch and euthanize all the feral cats and likely not even put much of a dent in their population. I grew up on a farm with a lot of feral cats, we didn’t hunt them as they helped with the uncounted number of mice/rats we had. Here’s the issue, they darn near breed like rabbits in the wild. They also had a high fatality rate, we never saw any one feral cat for years on end like you do a house cats. Disease and predation cull their numbers on a regular basis. Not only did we have feral cats but we had hawks, coyotes, foxes, dogs and non predators that would kill a cat if provoked. I pity the cat that decides a baby neutria is edible if one of the parents are anywhere nearby assuming the baby didn’t kill it first.
-You can’t license/chip/tag cats and keep them on your property like we do dogs. Cats are master of going under, through and over barriers so the only way you can have a cat outside and stay in your yard is to keep it in a cage or on a leash/chain. Do either of those and the ASCPA (and other animal rights groups) will be suing you for animal abuse. Doubt me? Look what they’ve done to change laws for keeping dogs.
-This one is on birds and because of the conversation on nesting habits. We had a pair of barn swallows that nested on the side of the house and returned every year to their nest. They would have 3 batches of babies with 3-4 eggs per batch. Almost 100% survival rate when they flew south for the winter. It’s species dependent on how many batches, eggs and survival rate you get. FYI, get a long term couple like these were and they damn near become domesticated, cat even treated them as part of the family and wouldn’t touch a baby that fell out of the nest. Parents would come screaming to us until we went to see what the problem was, they knew we would put the baby back up in their nest. The only real issue is they though it was perfectly OK to fly into the house, sit on the pictures, talk to us and crap all over the place (we had no AC so door/windows were always open during the summer). On the plus side they kept the fly and mosquito population in check so it’s all about trade offs.
Darrin ==> “-Cats do kill birds but I’ve only ever known one that was good at it and you would regularly see him hunting and catching healthy adult birds. ”
The threat of domestic cats to birds is MOSTLY to nestlings — see any of the KittyCam studies.
Feral Cats — It WOULD be difficult to totally eliminate feral cats — but not that difficult. It has been done wth dogs very successfully — and cats tend to clump together. The first step it to eliminate feral cat colonies.
Keeping cats in — Those who don’t wish to keep their cats indoors will simply have to forego cat ownership. There is a unending list of animals that we would not let people keep as pets if they chose to let them run free in the environment. Cats should be on that list. Re: Laws on dogs — it is illegal nearly everywhere in the USA to let your pet dog run free in the environment — it should be so for cats as well.
Working cats — there is a place for the working cat — which are mostly known as Barn Cats — barn cats generally not roam the environment but stay in their place and do their jobs where they have plenty of food (both human provided and through hunting barn pests).
The cat questioin requires rationality — and a proper solution is inhibited by the misguided emotionality attached to cats.
My impression is that there are two sides to the calculation. Many birds caught by cats exist because human activity creates food, such as earthworms in lawns – robins like those, and berry bushes.
Note also that some people say that barn cats are not effective unless they are fed some food. Dunno why, surprising.
Thankyou for information.
A negative mentality where I live likes to claim there are no more songbirds in the city.
Yet I see robins on lawns in the sun after a rain, eating earthworms.
One error is assuming the birds not only show up when the claimant is out and about, but also sing for them.
In reality birds utter whatever they do for a reason, when it is present. Perhaps happiness in some cases, but definitely to attract a mate (rock doves, aka pigeons, coo), to remind a mate where the nest is when their mate is out foraging, and as a warning (a harsh sound from rock doves). And to communicate to others abut danger – crows are quite loud, or maybe a good source of food.
(Behaviour will vary with species. Orcas for example were cavorting near Seattle last year when there was much of their favourite source of food – large salmon, which has not been as plentiful as they want. But the supposedly intelligent creatures limit themselves culturally whereas their itinerant cousins eat other things too. Yes, some humans are also Darwin Candidates, like those who suffer from lack of iron and vitamin B12 because of the diet they choose.)
And in the Victoria BC area there’s the misleading bird count at Christmas, which I say is not accurate because birds take shelter in poor weather or windy weather, birds vary location, watchers may not choose the best place to look, watchers may not stay out a s long or may stay home when weather is bad, smaller birds are less easily spotted, larger birds may be counted twice as they move away from a gawker.