httpv://youtu.be/Du9oQr8PQC4
This occurred at 10:20 AM April 12, 2004 in South Miami Florida. I was working in my kitchen at my home in South Miami Florida with my back porch door open, when my attention was captured by a loud “yelp-yelp” sound in repetition. I also noticed that I heard the “distress” call of a cardinal – similar to what I would hear if there was a cat or snake in my backyard. I grabbed my Sony cybershot 3.2MP and ran out my back door. On an adjacent pony tail palm (Nolina recurvate) just below the crown, about 8’ off the ground I saw a large knight anole (Anolis equestris) in a head down position. The anole had in its mouth, the back legs (below the knees) of a Cuban treefrog (Osteopilus sepentrionalis). The frog was making a very loud repetitive “yelp-yelp” sound while trying to climb out/away from the lizard’s mouth using its front legs. There were a pair of cardinals and mockingbirds, and a blue jay that were attracted to the sound. The cardinal was calling, and the mockingbird was approaching and slowly opening and moving its wings in a “swimming fashion,” making it obvious as it walked across the ground. The birds’ focus seemed due to the frog’s call. I have never experienced any reaction of a bird to the many resident Knight anoles in my property or elsewhere. I managed to get a short clip (meaning to take an image) and a captured still is what you see attached. After a few more cycles of yelping, the frog managed to break free from the Anolis’ mouth and hopped away behind my AC unit. Having had some firsthand past experience with Osteopilus’s antipredatory compounds, I wondered if they had the same effect on lizard’s bucccal cavity as they did on this (at the time intoxicated) human. I had heard a very similar call from an unidentified tree frog in Costa Rica 1998. It had been captured by a parrot snake (Leptophis sp.) that fell to the ground in front of a friends horse while we were jungle riding in Guanacaste. To humans, the call does sound very much like a baby, or toddler’s wail. I would be interested in knowing if it serves to attract other predators giving the “crier” a possible distracting means of escape.
Robert Heathcote
Awesome observation! There’s also some observations of equestris predating Cuban treefrogs in Walter Meshaka’s thesis.
Distress calls are still pretty controversial, and whether they function to startle an attacker, attract other predators to come and ‘help’, or attract other animals which start mobbing a predator, is pretty inconclusive. Personally I think the benefits can include all three depending on the scenario. Clearly more specialised/experienced predators should become less susceptible to being startled than generalist/naive predators, so the ‘startle’ effect could only work for the latter, but then the other benefits will start playing a role for experienced predators. There was some work done on this by Conover (will dig the reference out of you’re interested) with racoons and possums attacking caged bird (I think they were starlings) where distress calls were then blasted out of a loudspeaker…. some were bothered, others weren’t.
Distress calls clearly don’t startle most snakes (surely one of the most common predators of many tree frogs), and I doubt if they would startle many lizards either. I guess the benefit in your observation is that a lot of meso-predators become pretty wary if mobbing birds and animals start rocking up whilst they’re tackling a large prey item, which might distract the predator enough to make escape more likely.
Maybe of some relevance, but in the UK, you can get predators such as stoats and foxes to come running straight towards you if you mimic a rabbit distress call. Stoats or buzzard aren’t going to continue attacking a rabbit once a fox rocks up!
Armando Pou
That’s a great observation, thanks for sharing! I also live in south Florida and have seen large equestris take Cuban tree frogs during mid-morning hunts; particularly after a rainstorm or rainy night when the frogs are still out in daylight when Anolis are active. Whatever toxins the frogs posses do not seem to bother equestris. Perhaps it was as you note, an attempt to attract other predators, particularly mocking birds. This is breeding season, and mocking birds will absolutely drive any and all equestris from the general vicinity of their nests. I don’t think the cardinals or even the blue jays are as aggressive although they will mob and form a ruckus at the sight of any predator. Additionally, I have never seen mocking birds eat Cuban tree frogs, (an added benefit). It is interesting to note that all three (Mimus polyglottos, Osteopilus sepentrionalis & Anolis equestris) exist and may have co-evolved in Cuba.