Biologists knew the Oxbow Preserve was some the best habitat along the Animas River, but now they are getting a better picture of the many bird species it can support.
“The value is how many different species are there, that’s what encouraging,” said Brian Magee, a biologist with Colorado Parks and Wildlife.
This summer, biologists and volunteers spotted 76 species in the preserve and netted more than 300 birds during the hundreds of hours they spent completing a study funded by the city and Colorado Parks and Wildlife.
The researchers set up specialized nets in thickets and cottonwoods on nine days from May through August to catch and band birds.
The bands are tagged with an individual number that is part of a national database. This allows researchers to look up the bird if they are captured again.
Over time, this kind of work, called a Monitoring Avian Productivity and Survivorship study, can show how well a habitat is supporting bird life. There are more than 500 areas where such studies are conducted in the United States, but this is the only one in Southwest Colorado.
So far, biologists are pleased to see numbers consistent with last year.
“We have got some really good functioning habitat,” Magee said.
This year, it took the group 100 fewer hours to catch the same number of birds as in the previous year. But it is too soon to interpret what that might mean, he said.
The scientists also captured 42 of the same birds banded last year, which is positive because it means a portion of the population is surviving migration.
“Many of the birds we band at Oxbow migrate to Central and South America for the winter and return in the spring to nest. This is a significant migration with lots of perils along the way, including habitat loss, invasive species, pollution and insecticide use,” Magee said.
Researchers aren’t sure whether 42 recaptured birds is high or low at Oxbow.
Over time, the data at Oxbow could be used as a standard to help measure how successful habitat enhancements are working in other areas, he said.
The Oxbow has been closed from December through June for the last two years, and it was closed again this year.
The city’s Natural Lands Preservation Advisory Board had planned to keep the preserve open this year and next to collect data on how allowing people in the park might impact bird populations.
But Durango City Councilor Sweetie Marbury voiced concern about opening the preserve, so the preserve was closed until the council could take up the issue. The council is scheduled to make a decision on Jan. 12.
mshinn@durangoherald.com
