New research from the University of Utah and the Utah Division of Wildlife Resources (UDWR) finds that in dry years, birds funnel into the relative greenness of riparian (adjacent to river) environments. That increased diversity is accompanied by overcrowding that may cause increased competition for habitat and resources, the study finds, and an overall decrease in populations of birds who call the river home.
“In a changing climate, it is critical to understand how birds and other organisms are responding,” says Monte Neate-Clegg, recent U graduate and postdoctoral scholar at the University of California, Los Angeles. “From a conservation standpoint, the results are troublesome.”
“Riparian birds are reporting in on Utah’s most important habitat, the health of our riparian systems,” says Russell Norvell, Avian Conservation Program Coordinator for the UDWR. “We all know how crucially important water is in the West for human populations and everything else.”
The story of the study starts in the early ‘90s when UDWR and federal partners began monitoring bird populations in riparian areas in response to widespread concerns that riparian birds might be in trouble. At first, UDWR staff would go to a set location, stay for a set length of time, and record all the birds that they saw or heard during that time. The data generated from this method are called “point counts.”
In 1994, the program also began banding birds. In this method, a fine, nearly invisible net (called a “mist net”) is stretched across a flightpath, temporarily capturing small birds. Staff and volunteers carefully remove the birds from the nets, attach a small, light aluminum band etched with a unique number, and safely release the birds back into the wild. In such an effort, researchers repeat the mist netting at the same place many times and hope that they’ll find some banded birds in the nets in the future, allowing them to track the longevity of individual birds and then estimate the size and health of the population.