June ecology lessons 2015

Greg Gerrritt July 1, 2015

I keep spending more and more time in Providence’s North Burial Ground, and continue to find it the liveliest place in the city. For several years I have been filming the wildlife in the Burial Ground, with a special emphasis on life in two small ponds and especially the amphibians that inhabit them. This is my 4th year of study and the third year I have been filming. I decided to up the ante this year by getting a new camera, and setting a goal of creating a fictionalized children’s story on toad evolution, development and behavior from the footage I shoot this year.

I created some very interesting videos last year, using the process to further study the anatomy and behavior of Fowler’s Toad tadpoles. I was familiar with the mating behavior, somewhat, but realized that there were huge gaps in both my video footage and my knowledge of the Toads. I have doubled the number of hours I am spending with the camera in the Burial Ground and extended my night hours. I can not say my knowledge is in any way complete, but I can say that I have some amazing night time footage and know much more about the Fowler’s Toads, Gray Tree frogs, and Bullfrogs that inhabit the two ponds.

One of the things I learned this year is that Fowler’s Toads, at least a few, use the large permanent pond for breeding as well as the drainage swale. I did not realize they would try to breed in a permanent pond, and assumed if they did they would be unsuccessful. I heard, and have audio to prove it, that Fowler’s Toads call in the area of the pond amongst the Bullfrogs. In early June I saw some very small tadpoles in the pond right up against the peninsula that juts into the middle of the pond. I posted some video asking what they were since I have never seen very young Bullfrog tadpoles and was not sure what they looked like. Turns out I still have not seen young Bullfrog Tadpoles, and as these few tadpoles have developed it has become obvious they are Fowler’s Toads. As of July 1 at least one of the Fowler’s toad tadpoles in the large pond has some fairly well developed legs, appropriate for having been hatched several weeks ago, and something small Bullfrog tadpoles do not have.

Other video and naturalist highlights from the large pond include the very shy Great Blue Heron that I catch a glimpse of nearly every day, and the video of it swallowing a 12 inch fish that it caught as I was arriving at the pond. I have some closeups of a Red eared Slider turtle, have seen a nest laid by a snapping turtle, and have found that the population of Painted Turtles in the pond is at least 17, which is up 3 from last year and the most I have ever seen since I started watching. When I began 5 years ago there were 6 turtles.

Many people relish the larger pond and often I meet people there who tell me of childhoods in the neighborhood catching frogs and fishing in the pond. But my research is much more focused on the drainage swale/impermanent pond near the maintenance building just below the intersection of Branch Avenue and I-95. The drainage swale is about 75 ft long by 60 feet wide in a small bowl. It is entirely rain-fed, with a small watershed of cemetery roads draining in. It takes about 1/2 inch of rain to make the pond go up noticeably, but 3 inches of rain fills it up to a depth of maybe 18 inches. Its design is such that even 12 inches of rain could be absorbed with no threat to anything. The pond regularly goes dry, whenever we go three or 4 weeks with no appreciable rain. It went dry this year as soon as the snow melt was absorbed, filled up rains of May 31 and June 1, and then went dry again June 14. The second time it went dry was a bit traumatic as the frogs and toads were breeding as soon as the rains came, by June 9 there were many tadpoles swimming around, and thousands of tadpoles died from lack of water. I had seen small pools that had been cut off trap tadpoles before, but never had it gone completely dry with and entire crop of tadpoles. It was not a pretty sight.

In additon to studying the Tadpoles of the Burial Ground, I am concerned about amphibian populations and in conjunction with the Green Infrastructure Coalition I am exploring the use of rainwater green infrastructure for amphibian habitat in an effort to help amphibians in their struggle to survive the paving of the planet. I need to figure out how much water is necessary to get through breeding seasons and how to indentify appropriate places to put amphibian friendly green infrastructure.

June 15 it rained. And by the 16th the Fowler’s Toads and Gray Tree Frogs were calling and mating as if all was right in the world. By June 29 the mating had dwindled and there appeared to be only one Fowler’s Toad calling at the pond, but a number of Tree Frogs were still actively calling and frolicking. Spending more time among the calling night amphibians, for the first time I got to see and film the adults. I find that one tree frog seems to live in the stop sign at the corner right across from drainage swale, and i have footage of him calling at night before he leaps off the top of the sign and heads to join the fun in the pond. It will be interesting to see how late into the season breeding of the Tree Frogs goes.

The Toads , as it past years, seem to stop breeding earlier than the Tree Frogs, but again I have finally gotten to observe and film the adults so i am still learning. The toads are basically nocturnal (though I have audio of faint calling from the drainage swale in the middle of the day) and this year on a sand bank across the road from the pond (right next to the Tree Frog’s STOP sign) I found a number of Toad Burrows dug into the hillside. The first night I filmed a toad sitting in the burrow, and since have much footage of toads hanging out on the hillside after it gets completely dark. I also have figured out that on mating nights, once the females have mated they leave the pond, while the males keep calling until done for the night. I have on video several toads leaving the pond.

As of June 22 there was a new crop of tadpoles in the drainage swale. It takes a week for the eggs to hatch, so right on time. And almost every day since a new crop has hatched. When observing carefully one can now discern by size at least 5 different hatch days worth of tadpoles, and I expect there will be at least one more batch hatching soon.

While Gray Tree Frogs seem more numerous calling around the pond than the Fowler’s toads, Tree frog tadpoles seem to be much rarer in the pond. They are observed and filmed much less frequently, when netting fewer are caught. I am not sure why this is but have a few hypotheses that could be tested some day. One is that it is suboptimal habitat and that the Tree frogs are somehow constrained in mating even though calling loudly. Another is that the Tree Frogs use the pond differently than the Toads, not hanging out in shallow water for instance or staying further way from the shorelines so that I can neither see or net them. As yet it is a mystery, one that I will continue to ponder and seek evidence for.

Not much else new to report, but if you are interested check out the Moshassuckcritters Youtube channel https://www.youtube.com/user/Moshassuckcritters?view_as=public and the Late June video that inspired this essay. https://www.youtube.com/watch?v=hBurdpgfTp4

 

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