A team of biologists with the Colorado Natural Heritage Program of Colorado State University recently returned to YVLT’s Rehder Ranch Nature Preserve for the third consecutive year to study the large maternal bat colony residing in the historic Main House.
Led by Rob Schorr and Jeremy Siemers, the researchers joined YVLT at the Rehder compound to enjoy some grilled bratwurst before night set in, when the bats begin to stir from their mid-day lull.
Locating a suitable research facility to study bats was one of the team’s biggest challenges, explained Jeremy. “Abandoned buildings like [the RRNP Main House] are ideal for us; the hard part is finding a place where people don’t mind the bats living there,” he said.
Rob concurred. “We didn’t want to invest time and money in a project where the test group gets kicked out shortly thereafter, so this was a great opportunity for us,” he explained.
During their visit to Routt County, the team will also conduct bat research at the Carpenter Ranch, a Hayden-area property under conservation easement with YVLT. The multi-year study is documenting mortality rates among “little brown bats,” a population that has been decimated in recent years by the spread of White Nose Syndome (read more about the disease here). Researchers are also examining the bats’ activity levels at various times of year and how often they enter and exit the roost.
Pika inspecting the harp trap alongside Jeremy.
Members of the team spent the afternoon getting the Rehder facility ready for the evening’s research, including setting up the “harp trap” pictured above. The basic premise is this: researchers temporarily seal off the porch with netting, so when the bats emerge from their roost inside the Main House at dusk, they get funneled into the harp trap, depositing the bats into a bag situated below.
The biologists then “process” the bats by taking their weight and forearm measurements, photographing their wings (fun fact: the veins on their wings are unique to every individual, like fingerprints are to humans), and affixing a “PIT tag” – Passive Integrated Transponder. A PIT tag is similar to RFID tags for cats and dogs, assigning a particular frequency to each bat which allows researchers to determine when bats are coming in and out of the roost, as well as documenting their seasonal activity.
Jeremy and Rob prep the house before the bats ramp up their evening activity.
“There are probably a few hundred bats inside,” Jeremy estimated. “This is predominantly a female roost; they give birth and raise their young here. They actually love hot attics like this with the metal roof insulation.”
“We think the bats love this facility because they can get any temperature range they want,” Rob explained. “They can move around from hot to cool areas. Some were even discovered happily roosting at 113 degrees Fahrenheit.”
As the evening crept in, bats began to emerge from the roost and the researchers got back to work.
The process involves weighing the bats, taking forearm measurements, determining their age and sex, and tagging them with Passive Innovative Transponders. PIT tags allow researchers to track the bats from day-to-day and year-to-year.
“The Rehder Ranch has become a study site for a wide range of groups – biologists from across the county have come here,” said Rob.
We think the Rehder Ranch is pretty special, too. YVLT always enjoys hosting the CNHP team – thanks for visiting us at RRNP!