Invasive species.

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gopher
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Invasive species.

Post by gopher »

I am sure many of us have run into some invasive species during our herping trips, or as I would call them, adventures!
As a a novice to the world of herps I still carry my various field guides to see if my finds are native or introduced. (already lost one petersons field guid) :cry:
For the most part I have it all figured out but better safe than sorry.

My question is what do you do with them?

Some people tell me to leave them, other say to kill them. I admit to killing crayfish and a bullfrog at one point (which was already half dead due to the colder water). Other species I have run across were red eared sliders, I only caught one and was able to find a home for him.

Hopefully I don't come off as cynical but just from an ecological stance I just think introduced species should not be kept in native areas. To each their own however. For the most part I am curious to see what the seasoned herpers deal with this.
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Re: Invasive species.

Post by Zach_Lim »

That is a tough question.

Although I know the ecological impact of invasive species can be dire, especially with herps, I find it very hard to get myself to kill any living creature.

However, when I am able to get my hands on Bullfrogs (tadpoles or small ones), I often put them in a container and bring them home for my garter snake.

In San Francisco, we have invasive house geckos (now Tokays, apparently!) in Golden Gate Park. As they seem to just become food for birds and don't really bother any natives, I just enjoy their presence.
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gopher
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Re: Invasive species.

Post by gopher »

That is a good way to take care of the bullfrogs in your area. Most of my herping is done between classes so bullfrogs are safe as I don't want to be reeking of questionable pond water in class.

I am a bit biased as any invasive species is welcome to live around my home and neighborhood; but in wilderness biotopes my natural instinct is to remove them. There was a time there were a pair of anole lizards were living in my green house, and they were happily welcomed.

I am planning on joining a ranger reserve program and they have jobs where you are required to kill all the invasive species you come across.
Hopefully one can it can be seen as helping the environment as opposed to heartless.

If I ran across any geckos, Tokays in particular, I would certainly keep those as pets!
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Fieldnotes
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Re: Invasive species.

Post by Fieldnotes »

In urban settings or spots where invasive have become established it is wasted effort to kill. However, there are times when a single invasive or recent colony pops up beside a still present native population, such as Foothill Yellow-legged Frogs. If you feel there is a chance to save the native frogs from the invasive Bullfrogs then a worthy effort to remove the invasive is justified. Pescadero Marsh in San Mateo County, native Red-legged Frogs are currently battling introduced Bullfrogs. This place needs help now or more than just Red-legged Frogs may be lost; Bullfrogs will readily consume small-endangered snakes.



Zach_Lim wrote:In San Francisco, we have invasive house geckos (now Tokays, apparently!) in Golden Gate Park. As they seem to just become food for birds and don't really bother any natives, I just enjoy their presence.

Tokays? Are these indoor at the Museum?
I imagine winter in SF too cold for this gecko to be able to spread and sustain itself in the surrounding park. Have all age classes been spotted free roaming to show they are actually reproducing? Sometimes, they will last through the hot summer only to parish once experiencing a cold boreal winter.
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Jeff
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Re: Invasive species.

Post by Jeff »

When I lived in California there was a bag limit on bullfrogs. That may still be true, so watch what you are doing. There is some evidence that redlegs have an advantage over bullfrogs where both species occur, and the bullfrog tends to invade areas where redlegs have disappeared for other reasons (the Central Valley is an example). Bullfrogs are notably voracious feeders, but empirical cases that those in California are traumatizing native species are very rare. Evidence is welcome.

Jeff
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Re: Invasive species.

Post by Zach_Lim »

Jeff wrote:When I lived in California there was a bag limit on bullfrogs. That may still be true, so watch what you are doing. There is some evidence that redlegs have an advantage over bullfrogs where both species occur, and the bullfrog tends to invade areas where redlegs have disappeared for other reasons (the Central Valley is an example). Bullfrogs are notably voracious feeders, but empirical cases that those in California are traumatizing native species are very rare. Evidence is welcome.

Jeff
Per the Fish and Game Regulations:

20) Bullfrog (Rana (Lithobates) catesbeiana): Limit: No limit.
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Jeff
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Re: Invasive species.

Post by Jeff »

Thanks, Zach

I'm still dwelling on the 70s and 80s. The limit (I think 15) was a real biological head-scratcher.

Jeff
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gopher
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Re: Invasive species.

Post by gopher »

Jeff wrote:Bullfrogs are notably voracious feeders, but empirical cases that those in California are traumatizing native species are very rare. Evidence is welcome.
Jeff
The closest thing to scientific evidence is this example of extensive bullfrog predation on western pond turtles.
WESTERN POND TURTLE
Clemmys marmorata
Author: Jeff Lovich, United States Geological Survey, Western Ecological Research
Center, Department of Biology, University of California, Riverside, CA 92521-
0427

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Fieldnotes
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Re: Invasive species.

Post by Fieldnotes »

Jeff wrote:When I lived in California there was a bag limit on bullfrogs. That may still be true, so watch what you are doing. There is some evidence that redlegs have an advantage over bullfrogs where both species occur, and the bullfrog tends to invade areas where redlegs have disappeared for other reasons (the Central Valley is an example). Bullfrogs are notably voracious feeders, but empirical cases that those in California are traumatizing native species are very rare. Evidence is welcome.

Jeff
Red-legs have an advantage over Bullfrogs... And this is what?
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Southwest wanderer
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Re: Invasive species.

Post by Southwest wanderer »

I am no seasoned herper, getting a pretty good introduction in the past couple years. This discussion is very interesting. I personally have a very difficult time with the killing part. I enjoy the capture part, but then please someone else do it in for me.

When I took a trip to Florida, I was driving through the everglades at dusk when I came upon an enormous Python spread out across the entire road like a speed bump. My brain was telling me to run it over, but dang it I just couldn't do it.

I know how devastating these invasive species are on our natives, yet I personally have the hardest time with the killing.

Janine
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Re: Invasive species.

Post by hellihooks »

While a certain Arroyo Toad habitat I survey every year isn't overrun with bullfrogs... they are there, and I haven't noticed any drastic drops in Arroyo or Western toad numbers. I still kill every bullfrog I find.
I'll be there tomorrow night (Sat), so hopefully have an Arroyo post in a few days. If interested, pm me. jim
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Jeff
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Re: Invasive species.

Post by Jeff »

In response to the quote pasted by Gopher: I checked with Jeff Lovich and he replied this morning that he had no direct evidence regarding bullfrog/pond turtle depredation. The citations are difficult to trace (he's lost contact with Goodman, Dan Holland vanished over a decade ago and his reference was an unpublished report, and the other citation was in a turtle newsletter. However, he referred me to Dave Germano's work on pond turtles in bullfrog-infested waters in California, and I paste here what Dave published last year (Germano et al. 2012. Northwest Fauna, volume 7, page 87)

"As an example, it is often
stated in reports that American Bullfrogs
(Lithobates catesbeiana) are eating small-sized
Western Pond Turtles and, thus, reducing
recruitment into populations. Yet, these species
co-occur in many waters where turtles persist in
large numbers and young turtles are regularly
found (DJ Germano, pers. obs.). There is no
evidence in published literature, where the
scientific method was followed, to conclude
that Bullfrogs are causing declines in Western
Pond Turtles. Instead of being stated as a factor
in declines of turtles, this speculation should
be posed as a hypothesis that needs testing.
Further, if Bullfrogs are predators on small
turtles, effects may vary seasonally, by habitat
type, or by geographic location. We are not
stating that Bullfrogs are not a problem. Rather,
this anecdotal speculation has become fact or
dogma for some, yet no rigorous data have been
gathered to support this conclusion.
Although resource managers abhor duplication
of effort, replication is an important
component of scientific research. Too often,
data or evidence are collected at a site and
may be suggestive of a problem or a concern,
but without additional corroboration, often
transform into dogma. "

....which was my point, that the presence of bullfrogs, and occasional (even infrequent) observations of depredation have not demonstrated that they are having a negative impact on native species of turtles or amphibians. When FHF readers do kill bullfrogs, open them up and see what they have been eating.

Jeff
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Gluesenkamp
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Re: Invasive species.

Post by Gluesenkamp »

I vaguely recall a photo of a bullfrog eating a WPT hatchling in one of Dan Holland's slide shows many years ago. Pic taken in Oregon, I believe.
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Re: Invasive species.

Post by Fundad »

....which was my point, that the presence of bullfrogs, and occasional (even infrequent) observations of depredation have not demonstrated that they are having a negative impact on native species of turtles or amphibians. When FHF readers do kill bullfrogs, open them up and see what they have been eating.
I challenge anyone here to show young turtles and bullfrogs in the same pond habitats..

Hubbs is undertaking a massive effort to document as many ponds/streams that he can in Cali and also to show where he is seeing Bullfrogs and young turtles.. You just don't see many, if any, baby turtles if a good size and established Bullfrog population is, though you will still see plenty adult turtles.. Once those adult turtles die of old age, it may be game over at a number of locations..

Fundad
devlin
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Re: Invasive species.

Post by devlin »

While I'm not a fan of killing animals, when I see a baby SF garter and then look thirty yards away and see two massive, adult bullfrogs, I would not lose a wink over dispatching them (frogs).
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gopher
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Re: Invasive species.

Post by gopher »

Jeff wrote:In response to the quote pasted by Gopher: I checked with Jeff Lovich and he replied this morning that he had no direct evidence regarding bullfrog/pond turtle depredation. The citations are difficult to trace (he's lost contact with Goodman, Dan Holland vanished over a decade ago and his reference was an unpublished report, and the other citation was in a turtle newsletter. However, he referred me to Dave Germano's work on pond turtles in bullfrog-infested waters in California, and I paste here what Dave published last year (Germano et al. 2012. Northwest Fauna, volume 7, page 87)

....which was my point, that the presence of bullfrogs, and occasional (even infrequent) observations of depredation have not demonstrated that they are having a negative impact on native species of turtles or amphibians. When FHF readers do kill bullfrogs, open them up and see what they have been eating.

Jeff
Interesting, I will talk to Goodman about this in person tomorrow. He personally told me that he has dissected number of bullfrogs and has found baby wpt inside them.
While the frogs are not the only cause to the decline in wpt in my area, they certainly play a factor in preventing the populations from growing. Ultimately the population will die of when the older members kick the bucket.
I am certainly no expert, just someone who wants to know opinions and find out some answers.
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Re: Invasive species.

Post by Fieldnotes »

The thought about young turtles being safe from Bullfrogs sound nice. Any thoughts about how Y-L and R-L Frogs will be able to last once Bullfrogs overrun their ponds. There are factors beyond just one frog consuming the other; there is the factors of rivalry for food and other resources. Last week at the Mojave River, i noticed the pools that would normally have Western Toad and Pacific Chorus Frogs overrun by Bullfrogs. The remaining native frogs were forced into dense reeds.
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Jeff
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Re: Invasive species.

Post by Jeff »

Red-legs have an advantage over Bullfrogs... And this is what?
About six years ago I was involved in an e-mail exchange with several biologists regarding western ranid frogs, and Sean Barry made some very interesting observations based on his studies in northern California. My recollection is that he found bullfrogs had a very difficult time, if they could persist at all, in ponds with healthy red-legged frog populations. Details have suffered temporal ephemerality, so I leave the story here until I can contact Sean. One factor, though, is that red-legged frogs are winter breeders, and metamorphs appear shortly after bullfrogs have begun their reproductive ventures. That timing allows the small red-legged frogs to feed and grow while the bullfrogs are still in tadpole stage.

With due deference to Williams F's penultimate observation in the Mohave River -- From the late 1960s to early 1990s I was able to watch the decline of native ranids in California, Arizona and Montana. Generally, the native frogs were gone before bullfrogs moved in, and I believe that an assumption that bullfrogs forced the native species out is not supported in most cases.

I previously suggested, but now recommend, that FHF/NAFHA members propose a methodologically sound survey of bullfrog stomach contents in California. As part of the study, volunteers should note pesence or absence of native species. Native bullfrogs in Louisiana feed heavily on crawfish, and perhaps they are helping reduce invasive populations in the west.

Jeff
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Re: Invasive species.

Post by jonathan »

I know at least one lake in Vancouver, British Columbia that used to have red-legged frogs and pacific chorus frogs, then had bullfrogs and green frogs mixed in with the population, and now has no red-legged frogs and possibly no pacific chorus frogs left either.

As far as what to do with invasives, if I catch them then I donate them to the local natural history museum. The LACNHM has 4 southern water snakes, 2 Italian wall lizards, 2 Colorado River Tree Lizards (from the introduced population in S.B.), and 6 Mediterranean House Geckos courtesy of me.

Introduced lizards can also make great herp food, as my Pyxicephalus adspersus could attest.
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Re: Invasive species.

Post by shredsteban »

devlin wrote:While I'm not a fan of killing animals, when I see a baby SF garter and then look thirty yards away and see two massive, adult bullfrogs, I would not lose a wink over dispatching them (frogs).
Exactly. I know there are a lot of folks who are not into killing living creatures, but letting invasive species live, in some cases, is allowing a high possibility for vulnerable native species to be "killed" indirectly. But most people prefer to have peace of mind knowing that the blood is not on their hands when they allow nature to take its course. I also feel that even with our best efforts, we would be killing invasives at a relatively low number in comparison to the amount of natives the invasives are killing. I have a friend who did bird surveying for a living, and he carried a high powered pellet gun to take out all invasive birds he would find. I'm not sure if he would openly admit that to the law, but he knew the effects of negative changes in the avian community better than anyone else in some regions. I do wanna give Zach a thumbs up for finding great use with the bullfrogs. Anyone try taking the frog legs and dropping them in a frying pan?
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Re: Invasive species.

Post by mattg »

KILL ALL BULLFROGS!!! (WHERE THERE NOT NATIVE) and clawed frogs too!!
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Re: Invasive species.

Post by Zach_Lim »

I have always thought about taking home some of the larger bull frogs and cooking them...but I am not too sure on how to make sure they are "cleaned". I mean, generally people just munch on the legs, but is there any fear of parasites from under cooked frog legs (that is, non gut content meat)?

I guess frying them up would be good!
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Re: Invasive species.

Post by Snakeherper5 »

@Zach, if you properly gut and rinse the bullfrog, and fry the legs nice and hot it should kill any parasites. As you stated, just dont undercook them and follow proper sanitary food preperation guidelines. You can always make em a little well done to be sure, and another good trick is to soak the prepared bullfrog in vinegar for about 5 mins before seasoning and frying. This not only adds a nice flavor to the legs, but the vinigar can kill some bacteria and parasites and also helps cleanse the animal of other chemicals it may have encountered in its environmant.... (Eating a bullfrog captured in a pristine mountain stream might be prefferable, as oppose to one caught in a stagnant vernel pond next to a farm lol) I have eaten Bull frog legs a few times and they are pretty dang tasty i gotta say. Never hurts to try. I personally, like others on here, can't bring myself to kill an invasive animal. Only way I'll ever kill an animal is if it's suffering and death is eminent (like a snake that's been hit by a car and still alive)
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Re: Invasive species.

Post by dcooper137 »

Jeff wrote:In response to the quote pasted by Gopher: I checked with Jeff Lovich and he replied this morning that he had no direct evidence regarding bullfrog/pond turtle depredation....
Jeff - thanks for tracking this down. Always good to check what the citations are actually citing. Often the primary source turns out to be something even more general than what you're reading. I'm a huge fan of "pers. comm.'s" and use them all the time, but again, trying to get something resembling a record or observation into writing and citing that is so much more useful.

I can only add to this turtle/bullfrog debate that I was up surveying an area of lower Sespe Creek above Fillmore (Ventura Co.) last week, and stopped counting after around 50 pond turtles, of all sizes. Had several Bullfrogs "plunking", and had one of the largest ones I've ever seen (will try to post photo) sunning on a rock.

I'm inclined to believe that these debates can't be solved "once and for all", by stomach dissecting or otherwise, and that each site is really different. Sespe drains an enormous watershed with countless little tributaries where turtle refugia could persist if necessary. Contrasting this with a tiny farm pond up on a ridge in San Mateo County that might be far from any other water body is a totally different scenario. Have no idea how far up Sespe Creek bullfrogs get, but maybe all we can really say is that bullfrogs *can* extirpate, or at least replace RFL, but not always.
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Re: invasives; boolyfrogs.

Post by regalringneck »

Jeff, good on you to question the dogma, i hadn't, despite an affinity for anything ranid, (rather than rancid :p )

Dont know if you've had a chance to see this; a fellow named Travis posted the link on the news subforum : } http://www.eurekalert.org/pub_releases/ ... 031413.php

Hope you're able to dodge the twisters and mebbe send some of that moisture out our way, the deserts about as dry as ive ever seen it ... : {
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Brian Hubbs
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Re: Invasive species.

Post by Brian Hubbs »

Jeff just brought this to my attention. What a crock. The bullfrogs are definately a problem for the turtles (which they eat, ask Sam Sweet) and the red-legs, which they eat and I hear tell can pass chitrid fungus to. Probably more damage is done to the red-legs from the (hearsay) chitrid than anything else (but, I guess that needs to be studied while the frogs disappear). I have noted in my 3 years of intensive pond turtle documentation a lack of juvenile turtles at 90% of the places where I found healthy bullfrog populations. Just a coincidence? I don't think so. Most of the places where I saw both young turtles and bullfrogs were creeks and ponds that dried up in the summer, which is evidently a hinderance to the bullfrogs, but not the turtles or red-legged frogs (which have evolved to deal with CA droughts).

KILL all the bullfrogs you can. It's great fun. Use a pellet gun and hit them in the brain or dip net tadpoles. :x
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Re: Invasive species.

Post by hellihooks »

Brian Hubbs wrote:
KILL all the bullfrogs you can. It's great fun. Use a pellet gun and hit them in the brain or dip net tadpoles. :x
I read them your books aloud... they usually commit suicide by chapter two... :crazyeyes: :lol: :lol: :lol: jim
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Re: Invasive species.

Post by Zach_Lim »

Fieldnotes wrote:In urban settings or spots where invasive have become established it is wasted effort to kill. However, there are times when a single invasive or recent colony pops up beside a still present native population, such as Foothill Yellow-legged Frogs. If you feel there is a chance to save the native frogs from the invasive Bullfrogs then a worthy effort to remove the invasive is justified. Pescadero Marsh in San Mateo County, native Red-legged Frogs are currently battling introduced Bullfrogs. This place needs help now or more than just Red-legged Frogs may be lost; Bullfrogs will readily consume small-endangered snakes.



Zach_Lim wrote:In San Francisco, we have invasive house geckos (now Tokays, apparently!) in Golden Gate Park. As they seem to just become food for birds and don't really bother any natives, I just enjoy their presence.

Tokays? Are these indoor at the Museum?
I imagine winter in SF too cold for this gecko to be able to spread and sustain itself in the surrounding park. Have all age classes been spotted free roaming to show they are actually reproducing? Sometimes, they will last through the hot summer only to parish once experiencing a cold boreal winter.

I apologize that I never responded to this! Must have missed it.

You are correct- from what I am told, the Tokays are in and around some of the botanical houses within Golden Gate Park and Laurel Park (I highly doubt this, but a gecko breeder friend of mind swears he sees them), same with house geckos.
I have never seen Tokays, but have managed to spot one or two house geckos outside of these greenhouses near lights. This was a year or two ago.

I have not seen any since- as you noted, the Cold probably wiped them all out and what I saw was the first and only initial release of them.
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Re: Invasive species.

Post by Sam Sweet »

*((#@^ site dropped my log-in, I will retype later.

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Re: Invasive species.

Post by Fieldnotes »

mmm... Lobster and Froglegs..
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Re: Invasive species.

Post by Brian Hubbs »

:lol: :lol: :lol:

I think we're in for a banquet from the Master...
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Sam Sweet
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Re: Invasive species.

Post by Sam Sweet »

I recommend that everyone kill every bullfrog they can, anywhere outside of their native range. In addition to their role as predators, bullfrogs are basically immune to chytrid fungus and often have extremely heavy loads, shedding thousands of infective larvae daily and maintaining consistently high levels of infestation among sites and among years.

Like other ranids, bullfrogs will eat anything they can catch and fit in their mouths. Some years ago (1980s) we tried to stop bullfrogs from reaching upper Sespe Creek after a mess of them were introduced to some ponds nearby. For three summers we shot bullfrogs several times, on the first occasion having 77 lbs of dressed frog legs, from just the big ones. We checked guts on all the larger frogs, and found a broad range of prey. The most common large items were crayfish and small bullfrogs, with dragonflies and yellowjackets in almost every stomach too. I don't have the full list right at hand, but recall 3-4 each kangaroo rats and pocket mice, a gopher, a song sparrow, 3-4 Thamnophis hammondii to about 20" TL, several Bufo boreas including a couple adults, an alligator lizard and several small sunfish. There were no hatchling turtles in guts, although the ponds had a few adults.

I have only seen hatchling/yearling Clemmys twice in bullfrog stomachs (both in creeks), but I also can't think of any place that has significant numbers of both hatchling turtles and bullfrogs.

Bullfrogs are a big problem for arroyo toads where the opposite bank of a toad breeding pool has deep-water bullfrog habitat. Male toads come splash around and call for hours each night for 6-8 weeks, and the bullfrog(s) will cruise across and get them all. A saving grace is that bullfrogs do not move around much early in the season, so you can shoot out the frogs in or near toad pools and few or no bullfrogs will replace them until toads are done breeding. The point is that you don't need to shoot every frog on the creek to greatly reduce their effects in any given year.

We are a little bit lucky that bullfrogs are not very well adapted to western North America, in two critical respects. First, they hibernate in the stream vs. in terrestrial sites, and suffer near-total elimination in heavy flood winters. Second, they breed late and the tadpoles require a full year to reach metamorphosis, so when streams dry up in fall or flood heavily all of the previous years' young are lost. But for these attributes there would be a lot more bullfrogs in a lot more places. The larval stage length is an obvious candidate to be reduced by strong selection (whether favoring frogs that breed earlier or tadpoles that develop faster), and I always catch and pickle a gallon of tadpoles whenever I can so that one day we might have evidence of this.

There is no such thing as a good bullfrog, even dead. Our shootout did not stop the frogs from invading Sespe Creek.
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MarcLinsalata
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Re: Invasive species.

Post by MarcLinsalata »

Call me stupid, but why on the East Coast do the bullfrogs not apparently affect the number of turtles you can find at a given location? Do the frogs themselves just have more natural predators out there to keep them in check (birds, fish, raccoons, water snakes)? I can go to any spot I can think of that will be hopping with bullfrogs and I can scoop you out baby turtles all day long, too...... :?: As well as multiple species of smaller, more vulnerable frogs (carpenters, crickets, wood, leopards, etc....) :?:
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Re: Invasive species.

Post by hellihooks »

I survey for Arroyo's/bullfrogs every year at Deep creek... and kill every bullfrog I can.
Interestingly enough... I may accept the caretaker position this coming May, for the 2400 acres of land there, that encompasses the Arroyo Toad Habitat. In other words... I will live there, full time. Dream come true, really... it's my favorite place in the whole world. :) Hopefully I can make a real difference too... towards protecting the Arroyos there... :thumb: jim
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Re: Invasive species.

Post by Jeroen Speybroeck »

hellihooks wrote:I survey for Arroyo's/bullfrogs every year at Deep creek... and kill every bullfrog I can.
Interestingly enough... I may accept the caretaker position this coming May, for the 2400 acres of land there, that encompasses the Arroyo Toad Habitat. In other words... I will live there, full time. Dream come true, really... it's my favorite place in the whole world. :) Hopefully I can make a real difference too... towards protecting the Arroyos there... :thumb: jim
Sounds great, Jim!

Europe also has a number of bullfrog pest areas. A colleague of mine investigated different eradication methods on a population in my country. From what I gather from him and the few research papers I read on the subject, killing individual adult bullfrogs seems not a very productive eradication measure, as a seemingly endless line of sub-dominant individuals swiftly takes the place of the eliminated frog (often literally). It's a rather complex issue. Collecting tadpoles might work better, but can be costly (in terms of volunteer energy or otherwise). Early phase action is preferable, but of course that's often overseen... Another thing we see overhere is that bullfrogs not really threaten the more sensitive/critical herp species, as they mainly occupy degraded habitat (which is probably quite different in the US and CA).
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Brian Hubbs
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Re: Invasive species.

Post by Brian Hubbs »

I think bullfrogs are controlled by natural predators in the east, but most of those predators are absent in CA (like water snakes) and most native species do not like to eat them.
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Re: Invasive species.

Post by hellihooks »

Jeroen Speybroeck wrote:
hellihooks wrote:I survey for Arroyo's/bullfrogs every year at Deep creek... and kill every bullfrog I can.
Interestingly enough... I may accept the caretaker position this coming May, for the 2400 acres of land there, that encompasses the Arroyo Toad Habitat. In other words... I will live there, full time. Dream come true, really... it's my favorite place in the whole world. :) Hopefully I can make a real difference too... towards protecting the Arroyos there... :thumb: jim
Sounds great, Jim!

Europe also has a number of bullfrog pest areas. A colleague of mine investigated different eradication methods on a population in my country. From what I gather from him and the few research papers I read on the subject, killing individual adult bullfrogs seems not a very productive eradication measure, as a seemingly endless line of sub-dominant individuals swiftly takes the place of the eliminated frog (often literally). It's a rather complex issue. Collecting tadpoles might work better, but can be costly (in terms of volunteer energy or otherwise). Early phase action is preferable, but of course that's often overseen... Another thing we see overhere is that bullfrogs not really threaten the more sensitive/critical herp species, as they mainly occupy degraded habitat (which is probably quite different in the US and CA).
While deep Creek itself flows year round, the west fork of the Mojave (where I see the most Arroyos) typically dries out every summer/fall and I see scattered pools with 100's (if not thousands) of bullfrog tads... these (at least) I can do something about, as a full-time resident. :D
Start carrying a frog gig, as part of my herping gear, on my daily 'rounds' and gig every adult I see... I anticipate frog legs becoming a major staple in my diet... good thing I like chicken... :crazyeyes:
What blows me away is they'll PAY ME to live there... when I would pay TO live there... great herping... naked 'hippy chicks' abounding... plenty of peace and solitude... my own 'private' herping road (the now closed to the public 173)... I will LITERALLY be a Happy Camper... :lol: :lol: :lol:
You know where I live... don't be a stranger... :thumb: jim
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Re: Invasive species.

Post by jared68nova »

Fundad wrote:
....which was my point, that the presence of bullfrogs, and occasional (even infrequent) observations of depredation have not demonstrated that they are having a negative impact on native species of turtles or amphibians. When FHF readers do kill bullfrogs, open them up and see what they have been eating.
I challenge anyone here to show young turtles and bullfrogs in the same pond habitats..

Hubbs is undertaking a massive effort to document as many ponds/streams that he can in Cali and also to show where he is seeing Bullfrogs and young turtles.. You just don't see many, if any, baby turtles if a good size and established Bullfrog population is, though you will still see plenty adult turtles.. Once those adult turtles die of old age, it may be game over at a number of locations..

Fundad


There is a pond here in Eastern Alameda county that is overrun with bullfrogs and I still manage to find young pond turtles, the red legged frogs are very few and far between. I have caught (on accident) 4 WPT's and 2 red eared sliders while taking my ex girlfriend fishing for the first time... talk about a weird day off fishing. Used live shiners under a sliding float, only caught two bass and a crappie that day, the other 6 hooksets were on turtles of varied sized...oops :cry: I have convinced Bullfrogs to hit 8'' plastic worms while fishing too, so I know they would scarf a garter no problem. This pond however does manage, somehow... to cohabitate in large numbers, Bullfrogs, WPT's and RES's of all sizes, Pacific Chorus frogs by the 1000's in wet months, a few toads...and a dwindling population of Red Legged frogs. When late spring/early summer rolls around I'll take anyone interested turtle fishing haha. But yeah... Bull frogs suck, fry them legs up!!! I find they taste like a mixture of chicken and catfish... deep fry and serve with cold beer..not bad at all. :mrgreen:
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Brian Hubbs
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Re: Invasive species.

Post by Brian Hubbs »

How many years have the bullfrogs been there? I know that pond...saw two adult WPTs there in Oct. and no bullfrogs. We talked about that...
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jonathan
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Re: Invasive species.

Post by jonathan »

Jared's statement is a good reminder that different ponds have different conditions too. One place might have a certain bank or vegetation structure that allows hatchling pond turtles to hide from predation effectively, while another may not.

Up in the Northwest, I believe that spotted frogs are almost always wiped out when bullfrogs move in. However, there's one large lake in Washington where the two coexist. On one hand, the hydrology and climate is apparently a little different and allows the young spotted frogs to grow faster than the young bullfrogs. On top of that the spotted frogs in that area actually have a faster reaction time than other spotted frogs when faced with threats! Possibly a regional variation that has allowed them to survive coexistence with bullfrogs, and possibly the result of natural selection from living in a bullfrog-infested lake.

http://www.oregonzoo.org/news/2013/01/z ... og-mystery
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Re: Invasive species.

Post by hellihooks »

I wouldn't doubt that spotted frogs Jonathan speaks of are selecting for faster reaction times. I've seen such processes in play myself, and was actually the agent of change, in a population.

Doing 'live' herp ed talks for decades, I by necessity had to collect a lot of 'feeder' lizards, every year, typically Uts's and Sclops. I had several places where they both abound, but would only go to each spot once a year, so as to not exhaust any given area.

One particular spot is a quarter mile stretch of road bordered on both sides with large rocks, upon which Western Swifts would bask. At first, there was always a good number of swifts that would just sit there and allow you to easily noose them, but over the course of a decade, the swifts at that spot have become more and more unapproachable... now... it's nearly impossible to get within noosing range of any of them.

I sometimes wonder if I should feel guilty for changing the behavior of this (admittedly small) population, even though it improves their ability to survive... but fortunately, it's as natural for me to rationalize those concerns away, as it is for me to be an ultimate predator... :crazyeyes: :roll: :roll:

My point? Evolution happens a lot quicker than most might imagine... even with people. Since the advent of civilization, the human visual system now acquires and processes straight lines and right angles more readily than curves, except... in populations that still live in thatched huts... they still process curves better. :shock: :D

Change...is actually the only constant, for everything, including us. jim
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Re: Invasive species.

Post by Owen »

It's interesting how bullfrogs and red-legged frogs live together in the same ponds and maintain healthy breeding populations of both. The RLFs lay eggs earlier, around Feb. The young transform around July and occupy the shoreline in cover from the edge of the water to about 3 feet from it. They jump into the water to escape danger on the shore. As the season extends, you can find the young RLF under cover maybe 20 yards from the water. On the other hand, bullfrogs are laying eggs around April/May and the tadpoles don't transform until early the next years summer. The young frogs occupy the shallow water to the water's edge.

Where I find a problem is actually with black bass (Micropterus). In ponds with bass populations, I see healthy bullfrog populations, but not RLFs. My guess is that the huge number of eggs (10x RLFs) allows them to maintain populations when bass are present. Bullfrog tadpoles will also occupy the shallows up to the shoreline where bass are not present as opposed to RLF tadpoles usually staying on the bottom a distance from shore. I'm sure that many of the ponds that have bullfrogs had the frogs introduced as a food supply for bass.

IMO, the bass are a far bigger threat to young pond turtles than the frogs. If you've ever fished with a top water bait, you'll know what I'm talking about. Bass will eat anything that they can swallow and a 12" bass could swallow a 2" turtle with ease. I only see old adult turtles in ponds with bass. I've seen juvenile turtles in spots also populated with bullfrogs.

This turtle is basking on a rock on the side of a creek that contains bullfrogs:
Image
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Re: Invasive species.

Post by El Garia »

Owen wrote: Where I find a problem is actually with black bass (Micropterus). In ponds with bass populations, I see healthy bullfrog populations, but not RLFs. My guess is that the huge number of eggs (10x RLFs) allows them to maintain populations when bass are present. Bullfrog tadpoles will also occupy the shallows up to the shoreline where bass are not present as opposed to RLF tadpoles usually staying on the bottom a distance from shore. I'm sure that many of the ponds that have bullfrogs had the frogs introduced as a food supply for bass.

IMO, the bass are a far bigger threat to young pond turtles than the frogs. If you've ever fished with a top water bait, you'll know what I'm talking about. Bass will eat anything that they can swallow and a 12" bass could swallow a 2" turtle with ease. I only see old adult turtles in ponds with bass. I've seen juvenile turtles in spots also populated with bullfrogs.
BINGO! Decades of bass fishing and herping have proven this out, time after time.
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Brian Hubbs
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Re: Invasive species.

Post by Brian Hubbs »

So, all we need to do is get rid of the bass...I'm sure all the fishermen will understand how important that is and fall in line to voluntarily remove bass from CA... :roll:
And of course, CA F&W will stop raising them to plant in lakes...

I think we need some secret bass-shocking teams to roam the state and take care of this problem... :o
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Re: Invasive species.

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They've stopped stocking trout in some of the last Southern Mountain Yellow-Legged Frog streams, and even experimented with barriers to block trout from moving back in. Perhaps there is a chance that they could stop stocking bass in at least some CRLF ponds as well?
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Re: Invasive species.

Post by Helleri »

Seems to me like the whole matter should be handled on a case by case basis, considering heavily, what is the effect of leaving vs. removing it.

I think the first question to be asked in any particular instance is "Does feral necessarily equate to invasive?"

Now, in the cases where "Yes! get rid of that thing!" is the answer...fair game for pet feed.

But, calling it invasive, because it isn't native, might be a mistake in some instances. A few non-native species may have very well carved out a non-invasive niche' for themselves. And, if they are well established removing them might do more harm then good. I am thinking. If in a known area, a non-native species is discovered. A first good action might be to re-survey the entire area. And compare the results against the last census of the local inhabitants.

If there seems to be just as many in the same types of habitat as there was before...check back next season. Maybe just monitor new species to a biome for 2-3 years. Keep a close eye on them and if there is any sign that they are having a truly negative effect...Well it can't be too hard to get a crew of herpers out there to clear them out. Iv'e seen you guys go all fellowship of the ring over things like a slight range extension, after all.
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Re: Invasive species.

Post by klawnskale »

Helleri wrote:Seems to me like the whole matter should be handled on a case by case basis, considering heavily, what is the effect of leaving vs. removing it.

I think the first question to be asked in any particular instance is "Does feral necessarily equate to invasive?"

Now, in the cases where "Yes! get rid of that thing!" is the answer...fair game for pet feed.

But, calling it invasive, because it isn't native, might be a mistake in some instances. A few non-native species may have very well carved out a non-invasive niche' for themselves. And, if they are well established removing them might do more harm then good. I am thinking. If in a known area, a non-native species is discovered. A first good action might be to re-survey the entire area. And compare the results against the last census of the local inhabitants.

If there seems to be just as many in the same types of habitat as there was before...check back next season. Maybe just monitor new species to a biome for 2-3 years. Keep a close eye on them and if there is any sign that they are having a truly negative effect...Well it can't be too hard to get a crew of herpers out there to clear them out. Iv'e seen you guys go all fellowship of the ring over things like a slight range extension, after all.
Start with the Starlings, Gibraltor Rock Doves and English House Sparrows and go from there. They are so ubiquitous now on this continent that most people don't even pay attention to them.
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Re: Invasive species.

Post by Brian Hubbs »

I doubt the Med geckos are a problem...
or the Mustard or Licorice...but the thistles (like star thistle and all the others)...yeah, definite problem, as well as ice plant, castor bean, and tumble weeds (russian thistle). Oh, oh, let's not forget the largest invasive of them all...the stupid Eucalyptus trees.
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Re: Invasive species.

Post by Owen »

Brian Hubbs wrote:I doubt the Med geckos are a problem...
or the Mustard or Licorice...but the thistles (like star thistle and all the others)...yeah, definite problem, as well as ice plant, castor bean, and tumble weeds (russian thistle). Oh, oh, let's not forget the largest invasive of them all...the stupid Eucalyptus trees.
Around here, teasel is most annoying. The finches, bushtits (for the aphids) and anise swallowtails love the licorice!
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Re: Invasive species.

Post by jared68nova »

Brian Hubbs wrote:How many years have the bullfrogs been there? I know that pond...saw two adult WPTs there in Oct. and no bullfrogs. We talked about that...

The Bullfrogs I'm pretty sure have been there from damn near the beginning of the ponds construction. My best friend was born and raised in one of the houses that back up to the pond, his dad had moved into the house back in the late 70's and he said they almost wanted to sell the house after the first year because the noise from the Bullfrogs would keep him up all night during the summer :lol: They have definitely been there for 20 plus years. From what I remember from fishing that pond for the last 20 years, it seems like there actually used to be a whole lot more of them there back to about 10 years or so...probably all the feral cats that came in with the newer housing developments, that and of course the planting of Largemouth Bass. 10 years ago you would see Bullfrogs, or most any of the frogs for that matter.. out during all times of the day, they were everywhere...nowadays you mostly find them at dusk or after dark. Its sad to have watched this whole little pond area slowly deteriorate over the years... "dog people" everywhere throwing tennis balls in the water for their dumbass dogs thrashing habitat and leaving dog logs all over the bank, The place gets slammed by fishermen now after the word spread of 12lb bass and monster slab crappie ..I remember seeing garters, gophers and kings all around the area...cats and lawnmowers took care of that... Getting old sucks. :| But you can still find pond turtles and bullfrogs clinging on. The red leggeds are probably just about extinct at this location. I saw very few this year, infact I believe it actually was 3, 3 total... and I frequent the area atleast 2-3 times a week collecting Gambusia and baby Lepomis to feed my garters.
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