Wisconsin/Minnesota Treefrog ID

Hi Guys,

This was posted on another forum, and as it got no replies, maybe someone here might be able to help?

apparently this frog was found in this person's garden, but it doesn't fit anything from the northwest that i can think of, let alone the US! I reckon it's an escapee Hyla from Europe, maybe meridionalis??

http://i127.photobucket.com/albums/p122/BrokenChainsX/Frog1.png

Cheers!

I would say that maybe it's a Hyla squirella that somehow made it to the left coast.

Looks like Hyla chyrsocelis to me.

I have no idea what it is, but that´s not H.arborea, nor H.meridionalis, at least not a normal individual. The markings are too faded...

SludgeMunkey said:

Looks like Hyla chyrsocelis to me.

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I would agree. I was a bit confused by references to the Northwest. If the tree frog is from Minnesota or Wisconsin, there is no need to consider it an escapee. Hyla chyrsocelis and Hyla versicolor both fit the picture pretty well. The fairly smooth skin and the lack of visible blotch borders would indicate Hyla chyrsocelis. These two species were sparated in 1968 when it was dicovered that Hyla versicolor was a tetraploid, that is it has twice as many chromosomes as Hyla chyrsocelis. People commonly produce tetraploids in plant breeding, but I think they are uncommon in the animal world. The definitive identification is to count the chromosomes. Hyla chyrsocelis is more common on prairie edges. Hyla versicolor is more common in in forests. Hyla chyrsocelis has a faster trill. Either can change from gray to green but the borders of the blotched pattern of the gray phase are visible in a green adult Hyla versicolor. In my experience the newly transformed frogs are green and I can't tell them apart. Amphibians and Reptiles Native to Minnesota, Barney Oldfield and John J. Moriarty, University of Minnesota Press, Minneapolis, MN, 1994, has nice descriptions of these species.

eyrops said:

In my experience the newly transformed frogs are green and I can't tell them apart.

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I agree that it is a young gray treefrog. I find young ones like the one posted above in my mom's garden often during summer.

eyrops said:

The fairly smooth skin and the lack of visible blotch borders would indicate Hyla chyrsocelis.

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Are you saying that you can tell the two Gray species apart just by looking at them? Surely not?

I don't know what it is but its skin is awfully smooth to be a Gray Tree Frog, but I'm not familiar with young specimens yet.

Hey Will, can you link that other forum's thread please?

John said:

Are you saying that you can tell the two Gray species apart just by looking at them? Surely not?

I don't know what it is but its skin is awfully smooth to be a Gray Tree Frog, but I'm not familiar with young specimens yet.

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Oldfield and Moriarty describe the visual differences I mentioned. I've seen other authors say they were identical in appearance or that they cannot be reliably distinguished by appearance. The ones pictured in Oldfield and Moriarty did differ in roughness of skin and in whether the outlines of blotches could be seen in green colored adults. I do not have access to chromosome testing, so I do not actually know from my own experience which species I am looking at. I do trust Oldfield and Moriarty, though, and I'm willing to bet that at least some adult individuals can be visually placed in one species or the other.

eyrops said:

Oldfield and Moriarty describe the visual differences I mentioned. I've seen other authors say they were identical in appearance or that they cannot be reliably distinguished by appearance. The ones pictured in Oldfield and Moriarty did differ in roughness of skin and in whether the outlines of blotches could be seen in green colored adults. I do not have access to chromosome testing, so I do not actually know from my own experience which species I am looking at. I do trust Oldfield and Moriarty, though, and I'm willing to bet that at least some adult individuals can be visually placed in one species or the other.

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I don't mean to be dismissive Steve, but this seems rather hokey to me. I'm well read on Gray Treefrog literature and I've never seen anyone say "here's a a visual character you can use to differentiate these two species". One publication that springs to mind did find that limb length and various proportions vary slightly between the two Gray Treefrog species but both overlap too. Aside from the call and the chromosomes, I don't think there is a way to tell them apart just by looking at them.

John said:

Aside from the call and the chromosomes, I don't think there is a way to tell them apart just by looking at them.

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OK, John,

I'll retreat for now, but I may try to contact Oldfield or Moriarty to see where they are coming from and whether they have changed their minds since 1994.

-Steve Morse

eyrops said:

I'll retreat for now, but I may try to contact Oldfield or Moriarty to see where they are coming from and whether they have changed their minds since 1994.

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I had a look at that book online and it's rather lovely looking. With regard to their assertion, I would have thought they'd give some reference or other evidence to back it up - anecdotal evidence in a book is hard to believe in the face of such overwhelming scientific literature. I am interested to hear what they say, though. To make an assertion like this they would have to compare a lot of specimens over a large range and then have them tested genetically.

John said:

I would have thought they'd give some reference or other evidence to back it up - anecdotal evidence in a book is hard to believe in the face of such overwhelming scientific literature. I am interested to hear what they say, though. To make an assertion like this they would have to compare a lot of specimens over a large range and then have them tested genetically.

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You are correct that their assertion should be backed with genetic data. Their reference was:
[FONT=&quot]
Vogt, R. C. 1981.[/FONT][FONT=&quot] Natural history of amphibians and reptiles of Wisconsin. Milwaukee Public Museum, Milwaukee, Wisconsin. 205 pp.[/FONT]

I'll try to get my hands on this book to see what's there in text and references.

-Steve Morse

Hi Guys, sorry I meant to say North Midwest!

link is here: http://www.birdforum.net/showthread.php?t=143106