A team of scientists successfully moved sage-grouse, a threatened bird species in Washington state, from one area of their range to another to increase their numbers and diversify their gene pool.
A WSU study on the project in The Journal of Wildlife Management — “Effects of post‐release movements on survival of translocated sage‐grouse” — shows relocating the birds is a viable and productive step towards helping their population recover in the state.
“In the first year after moving sage-grouse in, they tended to move around a lot and didn’t reproduce as effectively as the native population,” said Kyle Ebenhoch, a researcher now working at the U.S. Geological Survey. “It took them about a year to settle in and get used to their new surroundings.”
Ebenhoch, a WSU graduate student during this project, wrote the paper with WSU School of the Environment professors Daniel Thornton, Lisa Shipley, and Jeffrey Manning. Kevin White, a contract wildlife biologist with the Yakima Training Center at Joint Base Lewis-McChord, was also a member of the research team. The training center hosts a population of sage-grouse where the relocation work was done.
Ebenhoch wanted to investigate how newly introduced sage-grouse would survive and reproduce in order to determine if relocating birds to the area could be a workable way of keeping the species from further decline in Washington.
It turns out, the birds can adjust, though the training center population continued to decline.
“The birds did adjust to their new surroundings, but it didn’t stabilize the population,” Ebenhoch said. “This can be one tool in our toolbox for helping, but we’ll need more research to find other tools as well.”
As for how the birds adjust, it’s not too far off from a person or family moving to a new state.
“It reminded me of me when I go somewhere new,” Ebenhoch said. “When I move to a different area, I know where my home and work are. Over time, I start to find a grocery store, or a barber. My knowledge and home range expand as I get used to the new place. It’s basically the same for these birds.”
The relocated birds, brought in from populations in Oregon, Idaho, and Nevada from 2004–2006 and 2014–2016, were fixed with radio-transmitting collars so Ebenhoch and his colleagues could track their movements and see if they survived in their new area.
The researchers also collared several native sage-grouse each year, to serve as a baseline on how much those birds move around and reproduce. That comparison produced conclusions about the one-year adjustment period.
The collars also had a “mortality signal” built in, so researchers would be notified if a bird perished while wearing a collar. This allowed the team to monitor the mortality rate of the native and transplanted birds.
Due to several factors, mostly human-caused like agriculture habitat conversion or wildfire, populations of sage-grouse in Washington have shrunk and become fragmented. There are four central and eastern Washington areas where the birds live, but they can’t intermix because these areas are too far away from each other. That leads to inbreeding and less genetic diversity at each area, potentially increasing diseases and abnormalities, which are important factors that biologists monitor when conserving rare or declining wildlife.
Ebenhoch hopes the paper, which was his thesis for his Master’s degree from WSU, will help policy makers and other wildlife biologists see that relocation can work. Though the paper is specific to Washington sage-grouse, some of the techniques may be suitable for sage-grouse conservation in other states, or even other species.
“This bird is right on the brink of being listed as threatened at the federal level,” Ebenhoch said. “We showed that relocation, while disruptive in the short term, can work once the birds acclimate to their new surroundings.”
ABSTRACT
Translocation is a vital tool in conservation and recovery programs, and knowledge of factors that determine demographic rates of translocated organisms is important for assessing the efficacy of translocations. Greater sage‐grouse (Centrocercus urophasianus) have been the subject of recent translocation efforts because of their declining range and their usefulness as an umbrella species for conservation. Using a long‐term data set on sage‐grouse in central Washington, USA, we compared movement and demographic rates of translocated and resident birds. Because newly translocated birds experience physiological stress during translocation and are released in unfamiliar habitat, we hypothesized their demographic rates would differ from residents. We analyzed 18 years of radio‐tracking data acquired from resident, newly translocated (<1 yr post‐translocation; T1), and previously translocated (>1 yr post‐translocation; T2) sage‐grouse between 1989 and 2017 to estimate movement rates, survival, and productivity. Newly translocated sage‐grouse exhibited farther daily movements (0.58 km/day) and smaller 95% home ranges (89 km2) than residents and previously translocated birds. Daily movements and sex influenced survival, but survival did not differ according to residency status. Furthermore, birds that survived to a second year after translocation exhibited shorter daily movements compared to their first year (urn:x-wiley:0022541X:media:jwmg21720:jwmg21720-math-0001 = −0.727 ± 0.157 [SE]), which corresponded with increased survival the second year (T1 = 0.526, T2 = 0.610). This decrease in movements and increase in survival the second year was not apparent in the control group of resident birds, indicating a possible behavioral link to survival of newly translocated sage‐grouse. Most productivity metrics were similar for translocated and resident birds, except for nest propensity (i.e., nest initiation rate), which was lower for newly translocated birds (35%) compared to residents and previously translocated birds. Our results reveal that translocated sage‐grouse exhibit temporary differences in some demographic parameters in their first year, which later align with those of resident birds in subsequent years. Similarities in adult and nest survival according to residency status further suggest that translocation may prove to be a viable tool for restoring and conserving this species. Continued declines in sage‐grouse populations in Washington, however, indicate that habitat conversion and fragmentation may be reducing demographic rates of residents and translocated birds, which warrants further study.