How the zoo is helping Mexican black bears in Texas

Mexican black bear cubs along the Rio Grande, NPS Photo.

Zoo partners with Big Bend National Park on wildlife conservation

By Rick LoBello, Education Curator

Last year in March the El Paso Zoo piloted a Zoo-Park partnership with Big Bend National Park to help the park conserve endangered Mexican black bears.  Funding was made possible when the Zoo and Big Bend National Park were awarded a $10,000 America’s Keystone Wildlife Grant (AKW). The grant partnered the zoo with the park to help recover black bears that had been impacted during the fur trade and westward expansion era of the United States.  The El Paso Zoo was among a small inaugural group of accredited zoos selected that met certain criteria, including AKW Field Conservation, AKW Citizen Stewardship, Community Engagement, and Sustainability.

The natural recolonization of the black bear to Big Bend National Park from the cross-border population in northern Mexico, is one of the most important conservation stories in Texas.   By the time Big Bend became a National Park in 1944, the park’s black bear population was apparently on a perilous decline.  When I started working in the park during the 1970s the bear was for the most part considered absent from the area with little hope that it would ever return on its own.  Then something very magical happened during the late 1980s, a sow black bear crossed the Rio Grande from a mountain range in Mexico and at some point, ended up being followed by a boar.

On July 13, 1988 a park visitor and I were able to document a large male bear (boar) and sow on video tape on two separate occasions. This same apparently breeding pair, was observed in the Chisos Basin and upper Green Gulch not far from the paved road north of Panther Pass.  Both bears looked very thin as they walked through an area of gray oaks.  In my estimation their condition could have changed during the following weeks as the Chisos experienced a rich harvest of pinyon pine nuts along with a fair harvest of acorns. 

A little over a year later on October 20, 1989, David A. Lloyd of Austin documented what few people thought they would ever see in the park, when he photographed a sow with three cubs while hiking on the Chisos Pinnacles Trail.  Mexican black bears have been on the rebound in Texas ever since.  

The El Paso Zoo-Big Bend National Park project focused on three components to help conserve bears in the park: (1) remove non-native invasive vegetation along the Rio Grande, (2) place additional food storage boxes in the backcountry and (3) bear-proof power line poles. 

Entrance to Boquillas Canyon, Big Bend National Park.

For the past ten years scientists working with land managers and restoration partners, have been working with Big Bend National Park staff on exotic vegetation removal on approximately 100 miles of the Rio Grande.   As a result of their efforts to remove species like athel tamarisk, sandbars are more visible and wildlife, from butterflies to bears, have access to habitats that are now more biologically diverse.   Questions yet to be answered include are bears staying longer along the Rio Grande riparian corridor and are more bird species and butterfly species being detected in habitats with improved conditions? 

Boquillas Canyon Tamarisk Treatment March 2019

As a result of the Zoo’s team helping treat athel tamarisk growing along the Rio Grande, the park has recorded an approximate 50% mortality of the exotic species.  This is good news for Big Bend and efforts to control exotic species.  The following picture shows how athel grows back after the treatment methods that were used. Sometimes treatment is effective on part of the tree, but one limb stays alive. Other times you see sprouting from logs or stumps that weren’t sprayed thoroughly enough. The regrowth was expected, within our ability to retreat, and overall, the park is really happy with how the former athel stands looked one year later.  Monitoring will continue and plans are being made to re-spray the treatment and then start focusing on treating a new reach within the same canyon.   

Boquillas Canyon

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