Reptile & Amphibian Forums

On friday night i went with my parents and a friend to the local "frog pond". There were both pacific treefrogs and spadefoots croaking together at the time. We heard probably hundreds and saw almost as many. As we were walking along, there were several pairs of frogs and toads in amplexus with the same species. But then, we saw something else. There was a female pacific treefrog and a male great basin spadefoot in amplexus! Now i had suspected this might have been happening but now I know for sure. Previous summers i have gone to that pond to get a few tadpoles for our backyard pond, and caught several "mystery tadpoles". They looked like a cross between a treefrog & spadefoot tadpole, and took longer to mature than all the others, but i never got to see the froglets(or toadlets, or whatever they were). Could this hybrid actually exist? I wish we had brought our camera along for documentation, but obviously we saw something cool so we forgot. Funny how that works. has anyone seen anything like this?
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Paullywog

Nobody's perfect. I'm nobody, so I'm perfect.

They were probably fighting... I highly doubt they could or would ever cross.

uuuh they really were in amplexus. we watched for a few minutes and they just stayed there. but fine, don't believe me. i mean, i was only there watching it.
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Paullywog

Nobody's perfect. I'm nobody, so I'm perfect.

Believe me, thats how frogs fight.... I dont think they can throw a left hook. For example there are several pics of Poison dart frogs in amplexus... one example is pumilio and tinc's (pumilio holding onto a tinc) and believe me thats not how those 2 frogs breed with their own species let alone another.

generally, when it comes to breeding, two animals of different species can only successfully breed if they are of the same genus, such as an american bullfrog, Rana catesbeiana, and the common green frog, Rana clamitans, create a commonly found hybrid in much of the eastern US. since pacific treefrogs are of the Pseudacris genus and western spadefoots are of the Spea genus it is possible they could amplex one another out of confusion, but intergenus breeding is not likly at best.

Of course they were in amplexus and not fighting. Male frogs' main criterion for mating is to grab onto the nearest correctly shaped object and hang on, They only let go when the female either spawns or makes specific movements to tell him she's already spawned. Obviously these are species specific so a spadefoot may not recognise the release movements of a tree frog. I often catch male frogs in amplexus with toads around here when the season overlaps. Last month I found a male frog in amplexus with one of my goldfish. he had one arm up each gill cover. As the previous poster said the species have to be very closely related to hybridise. Spadefoots and tree frogs are way too far removed. Lots of Bufos can interbreed when given the chance.

Hmm. Strange fighting method. Glad humans don't fight like that! Hahaha.
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Paullywog

Nobody's perfect. I'm nobody, so I'm perfect.

Hi Paullywog,

The frogs weren't fighting, the males that amplexed the wrong species were just confused. Male Pacific treefrogs have a standard 'fighting' behavior that they direct toward other male pacific treefrogs. They start by making an 'encounter call' that is distinct from the 'kreck-eeckk' advertisement call when another male gets too close. If the intruder doesn't leave, the male may attack him in a brief jump at him, but he does not amplex the intruder male for any long length of time.

It is not uncommon for frogs to amplex the wrong species in the excitement of the moment. See the attached photos of a male pacific treefrog amplexing a CA newt. Many frogs will occassionally amplex a female of the wrong species, but in most cases no viable hybrids are produced. In the case of a spadefoot toad and a pacific treefrog, they are far too evolutionarily divergent for viable hybrids to be produced.

Mike

my herp photos

Huh im curious, ive seen with my own eyes male tomato frogs in breeding season actually crush other male tomato frogs to death via amplexus. I would think that an animal that is unfamiliar with the warning behavior of the Grey treefrog would not respond to a warning call therefore would not move before hostile action took place. Also seeing as it was a male Spadefoot and not a male Pacific treefrog the aggression shown may be completely different (therefore possibly by amplexus). I dont see how you can completely disregard the amplexus as a possible act of aggression.

For anyone interested in the amplexus of the pumilio with the tinc, I refound the book it is in (The Encyclopedia of Amphibians; Robert Hofrichter). To make relevance of this it even states there that the amplexus was not a simple mis understanding during breeding season but a "Struggle for territorial dominance". This makes sense from an amphibians point of view, why would they want to share their breeding spot with an interloper...

Hi JaxMD,

I think it is highly unlikely that this represents aggressive behavior of a male spadefoot towards a female pacific treefrog. If you go out and spend a bunch of time in mating aggregations of spadefoot toads you'll see males making their advertisement calls quite close to one another. You can 'trick' the males sometimes by putting your arm under water and having your thumb pop out near a male, which will often grab onto your thumb. When a female or a non-calling male swims or hops past the calling male, the calling male will generally jump on them and grasp them in amplexus. If it is another male that they grab, the male makes a distinct release call, and the first male quickly releases it and resumes calling. This is a lot more consistent with the spadefoot toads being in a frenzy to breed, and grasping any potential female that comes near. Also, think about it from this perspective: the 'goal' of a breeding male is to mate with a female. In the short period that they have to find a mate, time that a male spends hanging onto another male is time lost during which they could have mated with a female.

I can't speak to your example of the tomato frogs breeding, as I've never observed their mating in the wild, or read any studies on their breeding behavior. Did you see this in the wild? I'd be interested hearing some more details. It is not uncommon for explosively breeding anurans, like many toads and wood frogs, to form large balls of multiple males hanging onto a single female. In these balls, the female and some males are occassionally killed. Here's a photo of a male wood frog in amplexus with a dead female.

Best,

Mike