by Greg Mayer
Lizards, as Grace Slick used to say, are the crown of creation. It thus is always a sadness to learn that horrible, predatory birds are eating them. And, what’s more, it turns out that seeds in the lizards’ stomachs wind up in the birds’ stomachs, which then eject the seeds in their pellets; this turns out to be an important form of dispersal for the plants.
These results are in a paper in press in the Journal of Ecology by David Padilla and colleagues in the Canary Islands. The lizards are members of a very interesting genus, Gallotia, which is endemic to the Canary Islands. They are in the family Lacertidae, which will be familiar to British and European readers of WEIT as wall lizards, sand lizards, and the like.
The BBC has covered the story, and has more superb pictures.
Padilla, D.P., A. Gonzalez-Castro and M. Nogales. 2011. Significance and extent of secondary seed dispersal by predatory birds on oceanic islands: the case of the Canary archipelago. Journal of Ecology in press. pdf
75 thoughts on “The horror”
I suppose this would be a bad thread to mention Baihu’s fondness for lizards….
Fondness for lizards, which would be kind of cute, or fondness for nomming lizards, which would be less adorable?
Oh, he’s quite fond of lizards. First, he runs up to greet them. Then, he hugs them tight and maybe even tosses them in the air out of sheer joy. And then he kisses them absolutely to death.
Most adorable, I assure you!
Well, as long as it’s in the name of science…
Have you tried planting any of his stool in the back yard to see if anything grows?
Well, I plant it in the dumpster in the alley. Does that count? I’m afraid I’ve never had a chance to examine the results of the experiment…you see, these large trucks keep coming along and emptying the dumpster, and I still don’t know where they take the contents….
Hmmm. I was going to suggest regular watering, but that seems a tad irrelevant.
It’s not cute and it’s not adorable. Letting pet cats out to kill the local wildlife is unconscionable, imo.
He most emphatically does not get “let out.” He only goes outside on a leash, and the blue-bellied fence lizards he preys on are no more remarkable than the grasshoppers he also noms.
Are you being funny? I can’t really tell, but unconscionable seems a tad too strong, too black and white.
Killing local wildlife can be a primary reason some people have cats. Sometimes the local wildlife are pests themselves and cats can do an adequate job of keeping their numbers in check (depending on the type of pest, of course).
Local wildlife? Cats are mostly useless against rats. Weak to useless on gophers (depending on the cat). Helpful with respect to mice. Absolute killers for lizards and small songbirds.
Coyotes are common wildlife pests — but cats are no help with them at all. You all know that story.
Cats are best kept indoors and away from the local wildlife, except from the occasional mouse that may sneak through a crack. Then the mouse police can come in handy.
Ding ding ding!
Mine only kills roaches (and I kinda disaprove of that, because I find roaches fascinating in their own way)…
I’ve always had a similar feeling with respect to mammals being killed and eaten by non-mammals. I’m very classist and I find it genuinely disturbing in nature programmes when I see non-mammals killing mammals.
I have suggested to people that we should launch a great crusade to hunt all such non-mammal species to extinction, but so far I’ve not had any takers.
I get something similar whenever I see an arthropod eat a vertebrate.
Yeah, spineless scum. String ’em up, that’s what I say.
Speaking of shrikes, my introduction to this species was during a winter walk when we came across a mouse impaled on a large thorn.
Initially we wondered what sort of (human) sadist was torturing animals but after some research discovered that shrikes do not have a strong enough jaw to tear apart their prey so they “age” them on a convenient thorn and revisit them when they have had a chance to “tenderize”.
Is that why they do it? Not simply caching?
I’ve accidentally caught shrikes while trying to trap kestrels with a bal-chatri, and the shrikes were quite capable of tearing holes in my not-so-aged fingers with their strong and sharp beaks.
Shrikes have sharp, hooked beaks. The impaling seems more like a compensation for not having a raptor’s talons.
I’ll have to dig out the bird books so I can give a reference as it’s been a while.
This was in south west Ontario (Toronto area).
It’s evolution in action! (Though technically it is a modern lizard.)
T-Rex was a “modern” T-Rex too…
I was expecting someone to say lizard gizzard which sounds like some 1970s rock group!
I was the founder member!
Also residents of Long Island NY, Topeka KS, a small but growing area of south-central New Jersey, and (reportedly) Vancouver BC and San Pedro CA, all of which have introduced populations of European wall lizazrds.
That is not good. Probably accidental imports. It is pretty rare to see them in the UK unless you pick the right spots – sand dunes are a good site. Last year when my brother was working at Knole for the National Trust, they had a lizard appear from a pot that contained an orange tree imported from Italy. It had to go to a local herpetologist as it would have been illegal to release it in case it mated with the local lizard population.
Did they identify the species?
I’ve never seen a sand-lizard in the UK…only common lizards and slow worms (and on only ONE occasion a grass snake). I get the feeling we (the UK) are losing our reptiles and amphibians.
They did but I cannot remember – he sent me a picture & I tried to work it out but if I recall correctly they can be quite variable…?
There are also some in Ohio. I was going to mention the introduced populations in the US, but it slipped my mind as I finished up the post. The introduced lizards are escapees/releases from the pet trade.
Yes, that’s right–Cincinnati. Threre are a couple of species involved, Podarcis sicula and P. muralis.
Good news for plants and birds, bad news for lizards, or will it force them to evolve a defense.
Lizards already have pretty good defenses against predators. Their camouflage is pretty good, especially when they’re still. They’re excellent sprinters and seem to always stay close to a hiding hole like a crack in a wall. Some species will readily shed (and later re-grow) their tails as a decoy, allowing the lizard to escape while the predator is occupied with the still-twitching tail.
But cats are amazing predators. Faster than lizards, superlative eyesight, enough intelligence to remember where the escaped lizard can be found the next day. They’re also quite skilled at flushing out prey that’s found a less-than-perfect hiding spot.
I think the lizard’s primary defense against cats is their prolific breeding — which, of course, means that they are themselves rather impressive hunters (insectivores) to be able to sustain their populations.
Domestic cats are also not subject to normal predator-prey ratios.
Just one of those things managed to wipe out my entire crew (of lizards) in less than 24 hours…
Yup. I have the only fence lizard population in my neighborhood and I think it’s because our dog does not allow cats in her yard. And, she’s not able to catch lizards herself, though she might try sometimes.
Well, she could probably catch alligator lizards, but they’re so secretive that she probably never sees them. I just had a very young one come into the house yesterday. I caught and put it outside under a lavender bush before any canids were the wiser.
Eh, I can guarantee you there are a great many lizard populations in your neighborhood, and the lizards in your own yard are by no means restricted to just your yard. They do, in fact, have excellent defense mechanisms against predation.
And why isn’t anybody here getting upset at all the insects the fence lizards eat? Y’all don’t think they breed and move that fast just by eating grass, do you?
Honestly, it borders on unbelievable how followers of a biologist’s Web site can be so ignorant of the most elementary grade-school facts of biology.
What facts are those, jackass?
It is an empirical fact that domestic cats can indeed extirpate local lizard populations. OK? That’s number one.
Number 2, your crack about the insects is simply stupid. My concern is not (so much) for the individual lizards you think it’s so adorable to see killed so unnecessarily. It’s for the populations of native wildlife that belong there in the local ecosystem. Your Friskies-subsidized killing machine and her neighborhood catbuds are imposing artificially and very likely unsustainably high mortality rates on the local lizards, rodents, and birds, none of which evolved with cats as part of the biotic environment. Fish in a fucking barrel, no matter how fast or camouflaged they seem to you.
In short, please think harder next time you feel moved to question the biological knowledge of others, because yours is damn crappy, and self-serving to boot.
p.s. I like cats; my family keeps 2. Inside.
And those facts have…what, exactly, to do with leashed cats?
Conversely, care to indicate where I’ve advocated that cats be permitted unsupervised outdoor access?
Or, perhaps, you could explain the great crime in a cat preying on such ubiquitous species as grasshoppers and western fence lizards? Is my understanding of their (perfect lack of) conservation status somehow erroneous?
You might try reading for comprehension in the future, you know. Could do wonders for your blood pressure.
that’s great! i hope you have a really good time watching your cat unnecessarily kill the lizards! the fact that the cat is on a leash and you’re there admiring its hunting skills makes it completely different from some irresponsible pet owner allowing his feline to roam freely…uhhh…right?
‘Scuse me, but where on Earth did y’all get this bizarre fantasy that cats are herbivores?
I mean, when he’s not snacking on lizards and grasshoppers and what-not, I’m feeding him meals of lamb and venison and bison. Do you expect me to feel guilty about feeding Bambi to him? How ’bout the chicken I ate for dinner tonight? What kind of guilt do I bear for that?
Like it or not, carnivory is an essential part of life on Earth. Eliminate it, and the whole web immediately disintigrates. What I personally have a hard time understanding is the kind of self-loathing that must go on in those who would thus destroy life. Do you weep for the viruses your immune system kills? How many tears do you shed for the termites I had poisoned so they wouldn’t eat my home?
‘unnecessary’ was the operative word; your cat doesn’t NEED to eat lizards to survive, and the ecosystem of the world will not collapse if it does not. the pleasure you seem to take in watching your cat kill pointlessly says more about you than it does biology; your ludicrous attempts to obfuscate by trying to refute arguments that weren’t made don’t say much for your intellectual honesty.
So, it’s okay for him to eat lambs and deer out of necessity, but it’s bad for him to eat grasshoppers and lizards because it’s not necessary for him to do so?
Do you have any idea how utterly bizarre that reads to me?
What is your criteria for determining necessity?
Would you be okay with me breeding and raising grasshoppers and lizards in my back yard to feed exclusively to him and foregoing the commercial diet altogether? What if I raised lambs and deer and slaughtered them? It’s not like Baihu can kill ungulates himself, you know.
Your “necessity” argument favors the small prey his ancestors have been eating for millions of years, not the large prey humans have only recently started “hunting” on behalf of cats.
Indeed, all there is to your “argument” is your own personal squeamishness about the facts of life. Sorry. Life is icky and messy. Death is inevitable. Sucks, eh? To be you, that is.
if you were actually interested in discussing the issue, your argument would not depend on making unfounded assumptions and putting words in my mouth, which is usually referred to as the ‘straw man’ fallacy.
You’re right. I’m not much interested in discussing the issue, because there isn’t any sort of rational “issue” worthy of discussion.
There’s nothing even remotely worng about a cat in Arizona eating western fence lizards, any more than there’s anything worng about a cat eating grasshoppers or venison, or a human eating bacon (which I will soon do for breakfast).
You’re the one trying to “open” a “discussion” by suggesting otherwise. Sorry, but I ain’t buyin’ what you’re sellin’.
put your money where your mouth is, mr natural, and let your cat go hunting unescorted and take his chances with the coyotes.
Ah — now it becomes clear.
You’e one of those people who hates cats, nothing more and nothing less.
But that’s your problem. Why you should expect others to share your irrational antipathy is beyond me, but what’s one more bit of irrationality added to your pile?
I have no problem whatsoever with the fact that I like cats and that cats eat other animals and that I don’t want one particular cat to get eaten. And I don’t have anything against the animals that the cats eat; it just doesn’t bother me that they get eaten, is all.
Yet it does bother you that it’s cats doing the eating, and it’s not-cats being eaten. Sorry. I ain’t got nuttin’ for ya. You’re the crazy one, and you’ll just have to learn to live with it, is all.
is it actually physically painful to be so stupid?
Cats are not even omnivores. The only vegetation they get is in the stomachs of their prey. If you try to feed them a vegetarian diet, as my sister-in-law did, they will be come ill. Biology. Ever hear of it?
I see no signs that Ben is an irresponsible cat owner. Ben takes Baihu out for supervised walks on a leash in his own yard. It’s not as though he’s decimating the lizard population in the Phoenix area. I seriously doubt that Baihu is even decimating the lizard population in his back yard. In fact, if I remember correctly, Baihu was a feral cat that Ben rescued, so Ben has actually reduced the number of lizard kills in his neighborhood.
Oh, but that’s not enough for Joe. Nothing short of trapping all cats and feeding them to wild coyotes will satisfy his bloodlust when it comes to the cats he so desperately hates.
i guess if the pain were commensurate with the stupidity, the knuckleheaded utterances would have ceased by now.
“I know you are, but what am I?”
Maybe I should copy / paste it a few times.
“I know you are, but what am I? I know you are, but what am I? I know you are, but what am I?”
allowing a domestic pet to prey on endemic wildlife is irresponsible. it doesn’t matter how cute or impressive it may be, or whether the pet only kills a few animals…it is irresponsible, for a variety of reasons, not least because it poses unknown risks to the pet itself.
There aren’t any risks to cats from eating grasshoppers or western fence lizards or any of the other endemic wildlife to be found in the back yard that he’d be interested in eating. None. Zero, zip, nada, zilch.
(Well, I suppose he could trip over his own feet and bruise his ego, but that’s a risk I’m willing to live with. Besides, it hasn’t happened yet.)
Care to try again?
Pretty sure fence lizards and grasshoppers are known risks. It’s the kind of thing feral cats live on. Thanks for your concern.
seriously, how do you KNOW that? given that your assertion is at odds with the advice proffered by wildlife organisations, veterinarians, and even feline advocacy groups, on what basis do you make that claim? and if you can respond without attributing to me things i did not say and views i do not endorse, it might be possible to have a constructive exchange.
Oh, what bullshit.
I challenge you to link to even one reference to a non-PETA-type organization that advises against leashed outdoor excursions for cats.
Unsupervised non-farm outdoor access? Sure. That’s a problem. But you’ll find that the only caution against supervised outdoor access is that the cat be current on all vaccinations — and, not only is Baihu current, his physical is in a few weeks where he’ll get whatever boosters he’s due for.
(To be fair, there’s also the PETA-style insanity that you’re promoting out there, but those self-loathing nutjobs see humanity as the must disgusting imaginable vermin.)
The reason this is such an unproductive discussion is that the only specific reason you’ve offered for your objection to my walks with Baihu is that you’d rather see me feed him to wild coyotes than let him eat those poor cute widdle defenseless grasshoppers.
I challenge you to link to even one reference to a non-PETA-type organization that advises against leashed outdoor excursions for cats.
that’s not what i objected to, and, as has been pointed out numerous times on this site, it is pointless and futile to ‘debate’ someone who refuses to address the pertinent points and tries to shift the argument with illogical digressions.
So, what were you doing all those times in the thread when you expressed great moral outrage at the fact that I was taking Baihu out on a leash and threatening dire consequences for the fact that I do so?
Face it, joe. All you’ve got is your PETA hand-wringing over your love of every sacred grasshopper. If you were anything more than bluster, you’d have posted something specific. If you want it, you can have the last word — until you offer up something in the peer reviewed literature that says there’s some sort of danger to me, Baihu, or the environment from our leashed backyard excursions, I’ll just laugh at you silently from the sidelines.
In the mean time, I’ve got actual work to do — and, later, a cat to walk. Maybe he’ll get lucky and catch that lizard he spotted the other day near the shed.
“all those times in the thread when you expressed great moral outrage at the fact that I was taking Baihu out on a leash and threatening dire consequences for the fact that I do so?”
never once did either. my first comment, in fact, made clear that i consider the matter of the leash irrelevant. last word: you, sir, are an idiot.
Is this the face of a wanton killer?
I wonder if this is the case with other carnivorous birds which eat seed eating creatures.
What I wonder is what the record is for the largest number of nested stomachs travelled through before successful germination.
This is most thoughtful and interesting comment so far. Thanks, Thanny!
The nesting process would depend on consumption of whole prey items, rather than those eaten in bites. True, shrikes consume their prey in bites, but they still eat the whole thing, eventually. I can imagine a chipmunk with its cheeks full of seeds eaten by a snake and in turn consumed by a coyote, and that would seem about as far as it goes. Some predators, such as hawks, dissect out the gut when eating prey, so they probably don’t disperse many seeds. Owls wolf down the whole mouse, so they would be better potential seed dispersers.
There used to be a fox in my rural backyard that would kill rabbits, and somehow ate everything but the stomach and intestines. I found several such remnants before I finally got a brief chance to see who left them.
“horrible predatory birds”??? horrible? No way! My avian dinosaurs are AWESOME! and by the way what about horrible snakes eating my birds?
This group of theropod dinosaurs are well cool, I agree – and some species display incredible levels of intelligence. I really like sulphur-crested cockatoos – they are stupidly sociable.
How can you not like birds? And according Wikipedia, that group of Tetrapods containing the most species.
Speaking of seed dispersal, we had a plumbing problem at the house a few years ago. It involved the sewer line clean-out in the back yard, a messy mess in the grass, etc. A few weeks later: Tomato plants!
Tomato seeds are persistent little buggers
Seeds eliminated in bird or animal poo get a nice nutrient package to help them grow.
There is christian style evidence this behavior resulted from teleological transfer between species. Now it has come full circle as the christian parents point to the bird eating the lizard and tell their children; “See that bird is eating its relative as we eat christ.”
Odd that these Canary Ids. lizards are eating so much fruit with ripe seeds. Some years ago I helped identify stomach contents of chuckwallas (large herbivorous iguanas)and I don’t remember seeing seeds at all in the pickled stomach contents that the herpetologists brought me. Lots of leaves, flowers, tender shoots and the like. Seeds? Not that I remember. Different organisms, different ecological settings.
I too was surprised by lacertids eating lots of fruit. Iguanas and relatives, as Achrachno notes, are more herbivorous. I specialize in anoles, and they are not big fruit eaters, but I have found small dark seeds in purplish feces, so they are passing intact. (I might even have a vial or two of seeds somewhere in my lab, or perhaps with anole specimens at the Museum of Comparative Zoology.) There are lots of natural history notes on anoles over at Anole Annals, but nothing on seeds; there is this account of frugivory in Anolis sagrei.
Interested if you posted this to gain comments from the group. Atheists are the least trusted group!
Thank you to above poster (Dawn Oz) for paving the way for my non-saurian post. This may interest your readers:
which headline is “Muslim medical students boycotting lectures on evolution… because it ‘clashes with the Koran'”
also featured in Pam Geller’s no-hold-barred blog Atlas Shrugs
It will surely hearten followers of this blog to know that the worst rated comment in the Times piece above (-2390) is the following: “evolution is just a theory, like ‘climate change’ it is all socialist-marxist science and needs to be stopped.”
Then read the comments on Geller’s blog and return to a depressed state.
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