Wildlife Conservation: Banding Together For A Songbird
It was your typical spring San Diego day. No clouds in the skies and tourists enjoying everything our beautiful city has to offer, including a visit to the San Diego Zoo Safari Park. As park guests meandered through the paved trails scientists with the San Diego Zoo Institute for Conservation Research, United States Geological Survey Western Ecological Research Center and Nature Reserve of Orange County slipped past them hiking through rugged trails used by wildlife and biologists.
On the 900-acre Biodiversity Preserve at the San Diego Zoo Safari Park, away from tourists, a U.S. Geological Survey biologist examines a wild cactus wren after banding the 8-inch-long songbird. The species is the focus of ongoing studies by USGS, San Diego Zoo Institute for Conservation Research, and Nature Reserve of Orange County scientists that focus on habitat restoration and understanding population dynamics of a species protected under the Migratory Bird Treaty Act and listed as a California Species of Special Concern. Photo taken May 9, 2011, by Ken Bohn, San Diego Zoo Safari Park.
The 1,800-acre San Diego Zoo Safari Park is home to 3,000 animals under its care, but it includes the 900-acre Biodiversity Preserve, designated only for local wildlife. Here, away from the tourists and the exotic animals, the Institute for Conservation Research scientists study native flora and fauna including the cactus wren, a songbird listed as a Species of Concern in California and protected under the Migratory Bird Act. This 8-inch long bird is the focus an ongoing study focusing on habitat restoration and understanding population dynamics.
On this beautiful day, I followed the coalition of scientists into what is a biodiversity hotspot. Amongst the native vegetation live a variety of reptiles, birds and mammals. But today we were listening for the distinctive call of the cactus wren. It was described to me as sounding like a sewing machine and sure enough it does! The brown bird can be distinguished from other local birds by the white strip over its eyes, creating the appearance of a white eyebrow. But it isn’t the bird’s song or its speckled body that is most unique, it is it’s choice of habitat.
“Cactus wrens only make nests in prickly pear or cholla catcus greater than 3 feet in height. Without it, they cannot survive,” said Bryan Endress, Ph.D., San Diego Zoo Institute for Conservation Research director of Applied Plant Ecology. “Native cactus and coastal sage scrub habitat is not only beneficial to cactus wrens but also supports a wide range of other native wildlife, and this is one of the reasons San Diego County is globally known as a biodiversity hotspot.”
The cactus wren is so dependent on this habitat that its numbers throughout Southern California are declining and becoming isolated due to urbanization and habitat loss. The 2007 Witch Creek wildfire added to the devastation when it wreaked havoc on San Diego County. At the Safari Park alone, 600 acres burned, reducing the available cactus scrub that this wren species relies on year round. These types of fragmentation can decrease genetic diversity which can increase this species’ chance of extinction.
“Our goal in this research is to determine how connected cactus wren populations are to one another and to be able to use this information to inform cactus wren habitat restoration projects,” said Barbara Kus, Ph.D., U.S. Geological Survey Western Ecological Research Center research ecologist. “We can then determine where additional connectivity is needed and make recommendations to guide cactus-planting scenarios that will eventually connect patches.”
Biologists with U.S. Geological Survey release a pair of cactus wren after banding them and taking genetic samples for a population study at the San Diego Zoo Safari Park.
The multi-disciplinary and multi-agency study’s goal is to add to the knowledge of this species before it becomes endangered. Little is known about the coastal cactus wren and its habitat needs or best practices for restoring cactus scrub habitat. So the biologists of several organizations have banded together to learn as much as they can from each other and from the birds themselves. This day, the hands of USGS scientists’ swiftly affixed tiny metal bands on wild cactus wren at the Safari Park and they collected feathers and blood samples from toe clippings for a genetic analysis of the population. Understanding the biology and habitat requirements of this species is an important part of ensuring proper habitat restoration and the cactus wren’s ability to rebound.
“Through this collaborative effort, we hope to determine the needs and requirements of this species to aid in its recovery,” said Lisa Nordstrom, Ph.D., San Diego Zoo Institute for Conservation Research scientist. “We are also monitoring cactus wrens at the San Diego Zoo Safari Park Biodiversity Preserve to confirm that our restoration efforts are having a positive effect on their population.”
So some scientists at the Institute for Conservation are monitoring the birds while others restore cactus habitat at the Safari Park. But throughout Southern California biologists are searching through prickly pear and chollas cactus for signs of a football shaped nest. Inside, they may find hope for future generations of cactus wren. It was never more clear to me that on this day that the work of conservationists goes unrecognized by the average person. As Safari Park guests enjoyed their tour watching herds of elephants, giraffe and rhinos, we were maneuvering carefully around thorns and looking through binoculars to protect the precious wildlife in our own backyard.
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