Feeding Invasives to Natives

So I feed Cuban Tree Frogs, Greenhouse Frogs, Brown Anoles, and sometimes Tropical House Geckos to either a Snowy Egret or Great Blue Heron.

My question is, is this considered a good way to “dispatch” of invasives, or considered rather… mean?

If you think about it, the birds are getting fed… I know some people euthanize frogs themselves but to me that seems hard.

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I think that’s pretty cool. It’s a form of biological control. If I could catch House Sparrows I’d totally feed them to local wildlife. Or my (indoors only!) cat.

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Thanks. I feel like the feral cats here are taking care of the house sparrows lol.

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In late summer I like to collect Japanese Beetles and throw them into Argiope webs.

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problem is, feral cats are also invasive so you’re just moving from one problem to another… not to start THAT discussion again

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Oh great I didn’t think about that :woman_facepalming:t4:

It’s preferable to kill animals first, before feeding them to another animal. It’s a cleaner death. These are prey animals, so their eventual death is likely to be at the beak of a predator, but it’s still better to kill them first. The egrets may not be interested in a dead animal, but something will, if you leave it out.

I can’t find the article at the moment, but I read a study a couple years ago that had been done on cane toads. They placed electrodes on the toads’ brains, so they would see if there were any pain signals received. Then they put the toads in a refrigerator for a few hours, before moving them to the freezer. There were no pain signals seen, so it was decided to be a humane method. That’s likely applicable to many reptiles as well. The fridge slows them down until they’re unaware, then the freezer kills them. The main problems are ones that can survive being frozen.

Another method, albeit a much more gruesome one, is to instantly destroy the brain via blunt force. I’ve killed severely injured lizards by placing them on the sidewalk, putting a paper towel over them, and crushing their head with the flat of a brick. It can’t feel pain if its brain is destroyed. But you have to be confident- you have to swing hard and finish the job in one motion.

If you want to feed animals to your cat, probably don’t. There’s a major parasite risk. If you absolutely have to, make sure to kill it first, cats are not known for clean kills. And, yes, don’t encourage feral cats.

For house sparrows, find the nests and addle the eggs. Shake the eggs vigorously for several seconds, which will kill them. You can also coat them in oil. No need to worry if it’s humane if you get the eggs young, bird fetuses aren’t thought to feel pain until halfway through development. Then, put the eggs back. The sparrows will spend a long time brooding eggs that won’t hatch, wasting their time and energy. Or, of course, you can trap and kill the parents. Don’t just destroy the nest, as they’ll move on to another nest, and quite possibly kill whatever was already living there.

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Thank you for your detailed response! I have found a few dead lizards, and the herons and egrets do eat them, although the other birds, such as crows, enjoy them the most. I do not feel comfortable killing a live and adult bird, although I have removed many house sparrow and starling eggs.

I have read an article about researchers bashing the heads of iguanas, and that seems to work the best for humanly killing lizards. With frogs, someone told me to “spray/rub benzocaine on them and place them in a sealed bag. Let the benzocaine settle in and they’ll fall asleep eventually, and after that you place them in the freezer where they will die a painless death. Then you can throw them away, or host a funeral in remembrance.”

I think that also would work instead of a freezer, although if I want to feed the frog to a bird, the freezer option is the best.

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I think it being a good way to dispatch an animal and being mean aren’t necessarily exclusive. A few thoughts:

As a researcher, this type of feeding generally wouldn’t be allowed in a controlled scientific setting. There is demonstrable stress and suffering occurring for the prey animal (reptiles and amphibians can certainly feel pain). I think sometimes we can tend to devalue invasive species a bit in terms of their suffering. So a good question is: would you feel that the level of suffering was/wasn’t justified if feeding a native species to a heron (a native frog for instance)? If that wouldn’t feel ok, I wouldn’t feed them.

I also think it’s worth pointing out that getting rid of a few individuals of an invasive species in this type of manner isn’t going to have any real positive impacts. All these species are firmly established, and a few individuals taken out of a population isn’t going to have any noticeable positive impact.

Euthanizing animals before feeding them is certainly an option (but again, with realizing that incidental taking of a few invasive individuals isn’t going to have a serious positive impact). However, the rules on euthanizing wild animals vary very widely from place to place and you could open yourself to the risk of getting in trouble for animal cruelty depending. As @fishkeeper notes, blunt force trauma to the head is a very quick and relatively painless way of killing vertebrates. In my opinion, it would be ethically preferable to feeding a living, pain-feeling organism to another if the sole goal is death of the focal individual. I’ve done this myself with injured animals (lizards/snakes hit by lawnmowers or cars but still alive), but it’s not pleasant (even if I think I’m doing what’s best for the individual animal).

Another option is just throwing the body of a dead organism in the water or leaving it on the ground somewhere other humans won’t find it. Plenty of things will find it and eat it (turtles, fish, insects, fungi, etc.) It won’t go to waste.

Last thought: Feeding individual animals frequently has its own consequences. They can become dependent on the food supply or attracted to areas and situations that are not advantageous for them. They become desensitized to human presence, they may eat too much and become unhealthy, they may have nutritional issues when supplemental food is removed, etc. So it’s worth taking into account whether feeding other animals will be having those or other impacts.

And yes, exposure to benzocaine and other oral anesthetics followed by freezing is a fairly humane way of killing amphibians. You should not dispose of any resulting bodies anywhere outside however, as that risks poisoning any animals which feed on the dead bodies.

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How do you catch them so easily. It seems that you get them alot Im curious because Id like to observe them.

My question is, where are you gathering those invasives, and where/how are you feeding them to the natives? If you gather the non-natives from other locations and then transport them to a different location to make them available to the natives, and set out the non-natives w/o killing them first, are you possibly spreading the non-natives if the herons, etc do not catch and eat them all?

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Brown anoles are quite easy to catch, as long as you wait for the right moment. I generally will come across an anole, and then walk away. Then I’ll come back, slowly walk up, and quickly put my hand around the tree. This will either scare them off the tree or closer to me so that I can use my other hand to catch one. The easiest way is to go to an anole-infested area during the night and start picking them out of the plants.

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The invasives are found in my yard and fed in my yard. Once or twice they have gotten away, but they usually don’t as the birds eat out of my hand. (ever since my neighbor’s tamed them with hotdogs, which can’t be good for them)

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Oh ok. So if I wanted to catch some geckos I should go to an area with alot of them in them and wait for the right chance?

Yes, and for house geckos, just get a butterfly net and use it to knock them off the walls and into your hands, or chase them until you can grab them.

Tysm this will help me alot

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But it’s not a bigger amount of suffering than what is felt by frogs that heron catch by themself?

As a researcher, this type of feeding generally wouldn’t be allowed in a controlled scientific setting. There is demonstrable stress and suffering occurring for the prey animal (reptiles and amphibians can certainly feel pain).

Not to mention many animals can and will fight back if you try to feed them to another animal. This is why, for example, it’s considered unethical to feed live mice and rats to snakes: in the wild the snake can often ambush the rodent at its leisure and minimize injury to itself (but notably it is still at risk), whereas in a captive setting the rodent can kick and bite the snake and cause serious injuri0es.

I think sometimes we can tend to devalue invasive species a bit in terms of their suffering. So a good question is: would you feel that the level of suffering was/wasn’t justified if feeding a native species to a heron (a native frog for instance)? If that wouldn’t feel ok, I wouldn’t feed them.

This is actually something I think might need to be discussed more often. There’s been this discourse that invasive species are worthless, but then that gets extended to all introduced species, whether or not they are actually harmful or whether or not they dispersed to the environment naturally or by anthropogenic means. There’s been a general trend in biology that all species that weren’t there when scientists first started surveying the area are pests that must be exterminated, and anything you do to them is acceptable, no matter how cruel and inhumane. I remember in mammalogy classes someone claimed that coyotes and red foxes were non-native and invasive in the United States, and it provoked a huge argument specifically because of this logic that “if they’re invasive, they aren’t legitimate animals and don’t have a right to exist”. I’ve even seen biologists and field researchers kill invasive organisms in horrifically cruel ways. This doesn’t even get into how someone might inhumanely kill a native species if they mistake them for an invasive. Reminds me of the creepy eugenics-esque “cleansing” that was done to try and save the red wolf, where in the mid 20th century they killed ~75% of the surviving red wolf population (mostly in zoos) believing them to be “tainted” by coyote and gray wolf DNA, only for it to turn out that red wolves originally evolved in a hybridization event between Canis latrans and C. lupus. Or how people argue whether the red wolf is a “legitimate” species that should be allowed to exist today.

What gets really creepy is how this dehumanization (de-something, I don’t know what the word is when it applies to animals) can easily get extended to humans, given how our species was an African-Middle Eastern endemic until about 90,000 ka and our species migrates so frequently. From a certain perspective it’s kind of hypocritical for our own species to consider the existence of any introduced species illegitimate. I’ve actually seen some biology professors with PhDs refer to specific ethnic groups of humans as “invasive species”, which is really creepy and I suspect comes from the fact that they were specialists in invasion biology (and thus this sentiment is pretty much an extrapolation of the mindset mentioned above). There are a lot of invasive species that are destructive and must be controlled for the sake of ecological health (garlic mustard, sea lamprey, alewives, house sparrows), but the current general attitude encouraging a lack of empathy for other organisms is concerning.

Euthanizing animals before feeding them is certainly an option (but again, with realizing that incidental taking of a few invasive individuals isn’t going to have a serious positive impact). However, the rules on euthanizing wild animals vary very widely from place to place and you could open yourself to the risk of getting in trouble for animal cruelty depending. As @fishkeeper notes, blunt force trauma to the head is a very quick and relatively painless way of killing vertebrates. In my opinion, it would be ethically preferable to feeding a living, pain-feeling organism to another if the sole goal is death of the focal individual. I’ve done this myself with injured animals (lizards/snakes hit by lawnmowers or cars but still alive), but it’s not pleasant (even if I think I’m doing what’s best for the individual animal).

Not to mention the way most animals kill their prey tends to be excessively cruel. Not because they want to be, mind you, but rather because natural selection doesn’t build animals for maximum efficiency in combat and killing, only what works well enough for the animal to be fed (and to be fair even the most humane ways that humans have invented for killing such as guillotines or lethal chemicals have been found to still cause a great deal of suffering). A lot of animals kill their prey by eating it alive, dismembering it limb from limb while still alive, or both (as in the case of crocodilians and most canids). About the only animal that regularly kills its prey with a minimum of suffering are felids. Cats are known to torture what they catch, but their hunting strategy lends them to kill prey with a minimum of suffering when they decide to get serious. I had a box turtle that I had to feed a fish to in order to give him antibiotics, and he killed it by dragging it out of the water, ripping its eyes out, and then waiting until it suffocated to death before eating it (needless to say, I vowed to never feed him any vertebrates again out of ethical concerns). Nature tends to be rather messy.

And yes, exposure to benzocaine and other oral anesthetics followed by freezing is a fairly humane way of killing amphibians. You should not dispose of any resulting bodies anywhere outside however, as that risks poisoning any animals which feed on the dead bodies.

As an addendum: never, ever try to euthanize vertebrates by freezing them. I’ve talked to some vets and they’ve said they’ve had cases where ignorant pet-owners have tried to euthanize iguanas and turtles by putting them in a freezer overnight, only to find them still alive when they come back the next day.

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The thing is a lot of people who do this kind of stuff tend to (perhaps unintentionally) torture the animal beforehand when feeding them to the other animals. E.g., for frogs people might break their legs beforehand to ensure that the frog cannot run away from the heron and thus not put the invasive animal back in the environment, which puts the animal in a lot more pain for a lot longer than if the heron were to catch them itself. I know of people who feed grasshoppers to herps that deliberately rip off their hind legs or pull off their wings first so they cannot escape.

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So don’t do it is basically what every one is saying.

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