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"Come Hell or High Water"


Fri, May 25th, 2001
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Monday, May 28, 2001

Weaver Dunes Field Report – Mid Spring 2001

Peepers and Chorus Frogs now sing in earnest from wetlands throughout Fillmore, Houston, Winona, and Wabasha Counties. The incredible din of these tiny inch long frogs an unmistakable, long anticipated, and quite noisy announcement of spring’s true arrival.

As I walk the dunes at Weaver, here in the third week of April, the love songs of these diminutive amphibians fill my ears. Of these two closely related species, the Chorus Frog is adapted to more open grassland habitats and the rasping click of their call emanates from every "fish-free" pond and other small temporary body of water in the region. Only in those areas with at least a modest stand of trees and shrubs, mainly Willow, Prickly Ash, Cottonwood and Birch, do the monotonous high-pitched peeps of Spring Peepers join in this springtime serenade.

Stopping to listen more closely, I hear the curious snoring grunts of a Northern Leopard Frog here and there as well. This comparatively large green frog with the black spots on its back, so familiar to biology students everywhere, typically does not begin calling in large numbers until somewhat later in the season. Unlike the larvae of their smaller cousins, which metamorphosis quickly, the young of Leopard Frogs frequently spend southeastern Minnesota winters as tadpoles and the premature calls of these few impatient adults provide an indication of the presence of deeper, far more permanent pools of water.

It is precisely these more stable bodies of water that I seek, as such will be where many of Weaver’s resident turtles will have also over-wintered. This is particularly true of Blanding’s Turtle, the main focus of the studies of my colleagues and myself, with some individuals sleeping winter away under the exact same sunken log or rock pile season, after season, after season. Turtles, it turns out, are quite the creatures of habit indeed.

In spite of the chilly temperature and the drab browns of Weaver’s still largely dormant vegetation, the voices of our three frogs assure me that Blanding’s Turtles are now awake and fully active as well. Possessing an almost uncanny ability to capture the feeble warmth provided by the rays of the still weak springtime sun, perhaps through the agency of their blue/black carapace or upper shell and despite an ectothermic or "cold-blooded" metabolism, Blanding’s Turtles can readily elevate their body temperatures well beyond the warmth provided by their immediate environmental surroundings.

This we have confirmed by the use of small electronic "data loggers," each approximately half an inch thick and about as big around as a quarter, which have been glued to the backs of selected turtles. These battery-powered, computer downloadable devices have been set to continually monitor the body heat of our turtles at 30 minute intervals throughout each day of the year and have frequently recorded temperatures thirty and even forty degrees higher than that of the ambient air!

Traps baited with cheap canned Sardines likewise provide certain confirmation of regional turtle activity and quickly catch the first Blanding’s, Painted, and Snapping Turtles of the season. The promising start to this year’s field research ends abruptly, however, as the snowmelt and rain swollen Mississippi River rapidly overflows to inundate area roads and fields. As floodwaters reach near record levels, most low-lying ponds are simply overwhelmed, becoming just another part of the muddy rampaging river.

Water levels in Weaver’s prairie "potholes," small water-filled sand dune depressions well isolated from the Mississippi, also rise dramatically, apparently in response to an increase in the underground aquifer. What have been little more then mere puddles in previous years are now sizeable ponds holding levels of water that tower well over my head. Narrow, normally placid Snake Creek is now wide and fast moving, a true river in every sense of the word. Appropriately and with more than just a hint of irony, snakes of various species festoon the branches of Snake Creek’s trees. Shallow, mud-bottomed lakes cover what are normally high and dry fields of corn and rye.

All of which means nothing to the turtles of Weaver, which steadfastly go about their business as if nothing has changed. About forty or so of these turtles, Blanding’s Turtles to be exact, carry expensive transmitters glued to their shells, radios which have allowed us to pinpoint their location and track their movements throughout all of last year. Transmitters that need to be serviced, refitted with fresh batteries and new antennas, and which may be lost forever unless recovered soon.

So come hell or high water, we will just continue trapping turtles at Weaver. Continue recording data on their sizes, weights and condition, and the locations of their capture. Transmitters will be refurbished and reattached, and the turtles that carry these radios will again be released to wander about for yet another year.

It is difficult to remember, however, that our turtle traps are now placed on what is normally dry land. That the lakes covered with White Pelicans, Ducks, Geese, and Coots that lay shimmering before my eyes are in reality flooded roads and fields. Of course, change is inevitable along the Mississippi, every river for that matter, which simply go where they will, when they will. This is something I believe turtles and other river dwelling wildlife already know full well. Too bad mankind has still not learned this lesson. Until next time, "Nuff Said" - JPL

John Levell

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