NMSU researchers estimate density, abundance of black bears in New Mexico


A black bear’s curiosity gets the best of him when he discovers a lure set by NMSU researchers. (NMSU photo by Matt Gould)
A black bear’s curiosity gets the best of him when he discovers a lure set by NMSU researchers. (NMSU photo by Matt Gould)

Using noninvasive genetic sampling, researchers from the Department of Biology and the Department of Fish, Wildlife and Conservation Ecology at New Mexico State University are leading the way in estimating the density and abundance of black bears in the state of New Mexico.

Funded by the New Mexico Department of Game and Fish, the research, in its third year, will conclude its data collection this summer in the Sangre de Cristo Mountains in northern New Mexico and the Sacramento Mountains in south-central New Mexico. 

“The goal is to provide accurate estimates of bear abundance that will contribute to the establishment of harvest objectives for the state,” said James Cain, assistant unit leader in the New Mexico Cooperative Fish and Wildlife Research Unit. The research unit consists of three NMSU faculty members, who support graduate students and post-doctoral associates through research topics ranging from native fish conservation to mammal resource selection and population ecology. 

The project includes Gary Roemer from FWCE and William Gould of the Applied Statistics Program at NMSU.

Ph.D. biology student Matthew Gould works closely with the research unit to gain in-field experience while applying statistical research to determine the necessary data on the bears. 

The management of the black bear populations will benefit from the research because the estimates of abundance are an integral part of establishing sustainable hunting quotas. 

Researchers use two methods to collect the necessary samples: bear rubs and hair traps. 

A hair trap is a single strand of barbed wire, which is stretched around 3-6 trees in a corral fashion at knee height. The barbed wire snags hair, allowing researchers to extract DNA from the root.

Bear rubs are different because they use the bear’s natural behavior to obtain samples. 

“They like to rub up against structures, which is a natural behavior,” Matthew Gould said. “We attach short strips of wire from knee height to head height and when they rub on these structures, the barbs collect hair.”

Bear rubs can be placed on anything, such as telephone poles, trees, posts and large buildings. 

Researchers will deploy hair traps every 5 km across the Sacramento Mountains. They will visit and check about 160 hair traps over six sampling occasions. The team will conduct the research throughout May to August. During travel days, researchers hike to the areas and camp at night. 

Black bears are generally active from mid April to mid November.

Looking at the bears’ genetic health allows the researchers to check if they are connected to any other populations and see any landscape factors that may influence movement between populations. 

“In the Southwest, these populations don’t exist as one contiguous population. They’re often separated, almost like islands,” Gould said. 

Researchers look at factors that may cause habitat loss and fragmentation and what the potential effects are on black bear populations. Factors could include transportation corridors, city developments, agriculture, or natural and human-influenced climate change. 

“As fragmentation and habitat loss occurs, the distance between populations may become greater, which may isolate these populations from each other,” Gould said. “If you have isolation, then over time these populations can become smaller, which may result in inbreeding. As inbreeding increases it can cause problems with health, reproduction and survival.”

This research and data collected from the study prove useful in many ways. 

“It provides a really good opportunity for training graduate students who are looking into fish and wildlife research as a career,” Cain said. 

Game and Fish funded the research to use the data in establishing sustainable harvest limits for black bear populations throughout the state, helping keep the bears on the landscape while still providing hunting opportunities. 

“NMSU is dedicated to conducting research that benefits all New Mexicans,” Gould said.

Watch this video on YouTube at https://www.youtube.com/watch?v=qw3HQqY6rQQ.

For more information on this, and other NMSU stories, visit the NMSU News Center.

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