OUTDOORS: Making head counts one strand at a time on Coastal Bear Study
By: JOHN FLORES
Underneath the canopy of a stretch of bottomland hardwoods a thick cloy odor of honey scent wafted through the gentle currents of air. The teasing smell was like the enticement of a bakery on Main Street before sunrise and rush hour traffic. It was unmistakably worth the pain.
The heavy bruin worked its way through two strings of barbed wire bound tightly around three trees forming a quasi corral. Several strands of hair pulled out of the bear’s hide from their roots and conspicuously clung to the barbs.
Days later, Wildlife Refuge Specialist, Matthew McCollister, also visited the corral. Meticulously checking each barb for any sign of bear activity, McCollister said, “We got several hits on this set,” clearly satisfied with the work and effort that had gone into setting up the corral.
Since 2010, a University of Tennessee study to try and determine population density, growth, and survival rates of the endangered Louisiana black bear has been going on in St. Mary and Iberia Parishes. Now in its second summer, the ongoing study is currently set for three years.
“Sometimes you’ll end up with a sample as big around as your thumb,” McCollister, who works for the United States Fish & Wildlife Service and is assigned to Bayou Teche and Mandalay National Wildlife Refuges, said. “Ideally you want 5 strands – 5 hairs – just because you need a certain amount of volume to do the technique. A single hair is not useable.”
Conducting the study in the two parishes this summer, which are considered the core area of the coastal bear population, is UT Graduate Research Assistant, Jesse Troxler.
Troxler, who is from Knoxville, Tennessee said, “We’ve got two wires, one on the top and one on the bottom. You go around three or four trees with maybe 10 feet between them and the top wire is set at 70 cm (27.5”) and the bottom wire is set at 35 cm (14”). The reason we do that is because there has been problems in the past with large bears going over the wire. Then if you put it too high small bears go under it. So, we have two wires where we can get both large bears and small bears.”
The study is being conducted on both public and private land says Troxler. Public land includes Bayou Teche National Wildlife Refuge; the only National Wildlife Refuge dedicated with a primary mission of preserving and managing habitat for the threatened Louisiana black bear. Of the 118 hair sampling sites Troxler has set up this summer, 100 of them are on private lands with 37 different landowners.
Sampling sites are set up in a specific grid to ensure biologists form an accurate picture of the population density by providing every bear an equal chance of capture and eliminating the potential for bias.
McCollister explained saying, “You want to have a density of traps that allow you to encounter all of your animals if possible. A lot of times they’ll decide they need four traps for every x-factor. Usually that x-factor is the average female home range size. Females have a smaller home range size than males do. And, there are several factors that go into determining a specific population – like births, deaths, immigration and emigration.”
Hair collected off of each barb is considered a separate sample. Hair caught on several barbs could mean multiple bears visited the set location and are treated as such, until DNA testing results prove otherwise. After the hair sample is removed using forceps, the barbs are burned using a propane torch to eliminate any chance of left over hairs that might taint subsequent samples later.
Troxler said, “The best hairs are the root hairs, where you can actually see some skin on them. Those samples are the ones they clip those roots from and use that. But, we burn the barbs to make sure there is nothing left from week to week. Part of this is important not only to identify which bear you get, but also which week you caught them in. You don’t want to leave a sample on there and come back and think you caught the bear again the next week. We also burn and sterilize the forceps we use to collect the sample keeping everything clean.”
McCollister points out the study is part of multiple agencies such as the Louisiana Department of Wildlife and Fisheries, USF&WS, and a variety of stakeholders public and private working together with the common goal of eventually delisting the black bear.
According to McCollister each threatened or endangered species has specific criteria. In order to delist this particular species three goals have to be achieved. There must be two main viable populations specifically defined as having a 95 percent chance of survival for over 100 years. Second, there must be critical habitat designation and preservation. And, third, exchange between populations.
Louisiana black bear population studies have been previously conducted in Tensas, Madison and Point Coupee Parishes, habitat that is superior and in a lot of ways more suitable for long-term viability when compared to marginal coastal habitat.
“Here in St. Mary Parish we don’t have a lot of that prime habitat, like Tensas. There (Tensas) it’s an optimum situation. Not only does it have great forests that produce on their own, it’s surrounded by matrixes of private land, with mixed WRP that are very productive. And, there the agricultural farming benefits the species as well,” McCollister said.
By comparison, St. Mary and Iberia Parishes are made up of coastal marsh and sugarcane for its agriculture that isn’t considered beneficial to bears, with remnant forests in between. Though bears have adequate soft mast to forage such a blackberries, the region lacks hard mast acorn crops that it and other species of mammals thrive on.
Bayou Teche NWR consists of 9028 acres of mixed cypress-gum and bottomland hardwood, but it’s only a small fraction of approximately 716,000 acres of land that makes up St. Mary Parish, which roughly 42 percent of is water.
Much of the hard mast crop production is limited to canal and bayou spoil banks and forest available on private land, near populated areas, where human encounters and traffic mortality do occur periodically.
Once studies are completed, it will take some time for biologists to determine the results of the population estimates and develop accurate computer models that may one day lead to delisting the Louisiana black bear. Until then one strand of bear hair at a time will be collected with hopes of achieving that goal.
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