Gunnison Sage-grouse: Population Genetics (Oyler-McCance)

Broad-tailed Hummingbird female (Selasphorus platycerus). Photo credit: San Andres National Wildlife Refuge, USFWS

Based on strong circumstantial evidence on numerous occasions, it is believed that adult female broad-tailed hummingbirds (Selasphorus platycercus) and one or both of her recently-fledged young remain together for two or more weeks after fledging. Due to proximity of banding sites to nesting areas in Rocky Mountain National Park, it cannot be accurately determined how long a family unit could remain together after beginning migration. The literature on broad-tailed hummingbirds reveals that the duration of maternal care beyond the first day is not observed. This study is using DNA analysis to determine whether groups of broad-tailed hummingbirds observed migrating together are family groups. USGS geneticists will isolate a set of polymorphic microsatellite loci directly from the broad-tailed hummingbird. These markers will then be used to determine the relatedness of individuals trapped together in Rocky Mountain National Park. Genotyping is achieved by extracting DNA from a tail feather from each trapped bird. Managers can use this information to monitor levels of genetic variability in populations.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Greater sage grouse (Centrocercus phasianus). Photo credit: Copyright R. Bruce Gill, courtesy of Animal Diversity Web

The Greater Sage-grouse recently was considered for listing under the Endangered Species Act. While it did not warrant the listing based on current science, questions remain about the genetic viability of, and distinctions between, different populations of this bird. Sage-grouse currently inhabit 56% of their historic range, leaving some populations isolated from each other. USGS scientists completed DNA analysis of Greater Sage-grouse sampled across their entire range of 11 states (including Wyoming) and two Canadian provinces. These data evaluate boundaries between Greater and Gunnison Sage-grouse populations as well as the two described subspecies of Greater Sage-grouse. In addition, the data provide information to help understand gene flow, genetic diversity, and evolutionary history between many additional populations. Collecting the same data across the entire species range made it possible to make comparisons between all surveyed populations. This will help managers develop species-wide management strategies that take genetic distinctiveness into account based in part upon the entire "genetic landscape" of the species.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Gunnison sage grouse (Centrocercus minimus). Photo credit: Copyright Dick Williams

Capture-recapture (CR) is a very important class of methods and models for study of wildlife populations and can be used to obtain movement information and estimate population abundance, survival probabilities, and population trends. Recently, biologists have begun using an individual animal's unique DNA as its mark. This is particularly useful in cases where DNA can be collected non-invasively. In this study USGS investigators are attempting to apply CR methodology to estimate population sizes of Gunnison Sage-grouse, a species of high conservation concern. DNA from Gunnison Sage-grouse is being extracted from fecal pellets collected on leks and used to uniquely identify individuals.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Gunnison sage grouse (Centrocercus minimus). Photo credit: Copyright Robert Bennetts

The newly described Gunnison Sage-grouse (Centrocercus minimus) is a species of management concern because of marked declines in distribution and abundance, a consequence of the loss and fragmentation of sagebrush habitat. This has caused remaining populations to be unusually small and isolated. USGS scientists used genetic data to assess the extent of population subdivision among Gunnison Sage-grouse populations. They found a high degree of population structure and low amounts of gene flow among all pairs of populations except the geographically adjacent Gunnison and Curecanti populations. Population structure for Gunnison sage-grouse was significantly higher than has been reported for Greater Sage-grouse (C. urophasianus). Further, investigators documented low levels of genetic diversity in some populations, indicating that translocations from larger, more genetically diverse populations may be warranted. This information can be used in conservation plans to guide monitoring and management actions that maintain genetic diversity and help ensure population persistence and species viability.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Kirtland's warbler. Photo credit: D.K. Dawson

Kirtland’s Warbler (Dendroica kirtlandii) is an endangered nearctic/neotropical migratory bird species, utilizing jack pine forests in Michigan, USA as the summer nesting habitat and overwintering in The Bahamas archipelago.  While recent demographic analyses suggest that individual warblers move regularly between geographic colonies no data exist on population structuring or on levels of genetic diversity.  Information on the extent of population structuring, extant levels of genetic diversity, and effective population size is essential to the evaluation of the current recovery program for D. kirtlandii and for any further consideration of the species’ endangered status.  To address these information needs, scientists from the Leetown Science Center, California University of Pennsylvania, and the USDA Forest Service’s International Institute of Tropical Forestry, USDA Forest Service have developed and characterized 23 microsatellite DNA markers for the nearctic/neotropical migrant passerine.  Multilocus genotypes resulting from this suite of markers should reduce the amount of resources required for initiating new genetic studies assessing breeding structure, parentage, demographics, and individual-level ecological interactions for D. kirtlandii. 

For more information contact Timothy L. King at the Leetown Science Center.

Lesser praire-chicken (Typmanuchus pallidicinctus). Photo credit: U.S. Fish and Wildlife Service

The Lesser Prairie-Chicken (Tympanuchus pallidicinctus) has one of the most restricted ranges of North American grouse, having sustained marked reductions in suitable habitat over the past 100 years. What remains is a highly fragmented distribution throughout its range. Despite a slowing in the rate of habitat loss, populations have continued to decline range-wide, and the bird is considered a “warranted but precluded” threatened species by the U.S. Fish and Wildlife Service (USFWS). USFWS managers are concerned that genetic diversity within individual populations might not be sufficient to maintain them. Using mitochondrial DNA sequence and nuclear microsatellite analyses on three Kansas populations of Lesser Prairie-Chicken, Fort Collins Science Center scientists and collaborators at Kansas State University are determining if this is the case. The results will help managers determine the best conservation practices for these birds at local and regional levels.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Micronesian kingfisher. Photo credit: Copyright John White

The Guam Micronesian kingfisher is extinct in the wild and only occurs in zoos in the United States. In a comprehensive study, molecular markers were used to identify the genetic relatedness among the captive birds so managers could develop a viable breeding strategy and plans for release of the birds back to Guam. Wild Micronesian kingfishers living on Pohnpei also were studied to help develop release plans. Researchers discovered that the Pohnpei birds, hence likely the Guam birds, were cooperative breeders, which means that offspring from previous nests stayed with the parents to help raise the chicks. This was a key clue to improving success in the captive Guam birds because previously older chicks were taken away from parents.  Scientists also learned that kingfishers on Pohnpei were highly territorial, an important fact if their dispersal options are limited by territory vacancies and forest resources as might be the case for the Guam birds. The killing of one sibling by another was also observed which underscores the importance of understanding evolutionary history of the birds.

For more information view http://fresc.usgs.gov/research/StudyDetail.asp?Study_ID=101 and contact Susan M. Haig, Forest and Rangeland Ecosystem Science Center.

Mountain plover. Photo credit: Fritz Knopf

Mountain Plover (Charadrius montanus) distribution and abundance have drastically declined in the past 30 years, and the conversion of shortgrass prairie to agriculture has caused breeding populations to become geographically isolated. This isolation, coupled with the fact that Mountain Plovers are thought to show fidelity to breeding grounds, leads to the prediction that individual breeding populations would be genetically distinct. If observed, such a pattern would have important management implications for a species of concern. However, when USGS scientists examined genetic variation at two mitochondrial regions for individuals from several breeding sites, they found no evidence of significant population differentiation. Further analysis suggested that the Mountain Plover underwent a population expansion following the Pleistocene glacial period. To explain the lack of detectable genetic differentiation among populations despite their geographic isolation and fidelity to breeding locations, investigators speculate that there is sufficient female-mediated gene flow to homogenize gene pools among populations. Such gene flow might ensue if pair bonds are formed in mixed flocks on wintering grounds rather than on the summer breeding grounds.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

Endangered Puerto Rican parrot. Photo credit: Tom MacKenzie, USFWS

The Puerto Rican parrot is considered one of the most endangered birds in the world. During Columbus’ time, the parrot population may have exceeded one million but dropped to a low of 13 by 1975. For over 30 years, scientists and managers have studied and nurtured the few remaining wild and captive parrots. USGS scientists at the Forest and Rangeland Ecosystem Science Center and North Carolina Cooperative Research Unit have spent more than a decade working with federal agencies and the Puerto Rican government to establish family trees for the captive and wild populations. Molecular markers have been used to identify individuals and verify their lineage to model potential strategies for moving birds to and from captive and wild populations and to set up pairings for breeding programs to maximize genetic diversity. Recovery of the parrot is far from realized, but some birds are being released into the wild.

For more information contact Susan M. Haig, Forest and Rangeland Ecosystem Science Center.

Adult western snowy plover. Photo credit: Courtesy of Morgan Ball

Resting western snowy plovers. Photo credit: Courtesy of Morgan Ball

Snowy plovers that inhabit the western coast of North America currently are listed under the Endangered Species Act as a distinct population segment (DPS) from other snowy plovers that inhabit the Great Basin and southeastern United States. An analysis of genetic information was conducted to examine whether there were significant genetic divisions, for example subspecies, among snowy plovers in North America and the Caribbean. Using snowy plover data from up to 15 breeding areas and from 155 different snowy plovers, few genetic differences were detected within the continental United States, suggesting there are no separate subspecies within the United States. More specifically, there was no evidence that the western snowy plovers were genetically distinct from those in the Great Basin. Other research has described population characteristics that distinguish the coastal population from inland birds, and this information can be combined with the genetics information in considering taxonomic and management decisions.

For more information view http://fresc.usgs.gov/research/StudyDetail.asp?Study_ID=425 and contact Susan M. Haig, Forest and Rangeland Ecosystem Science Center.

Spotted owl

Spotted owls are mostly non-migratory, long-lived birds whose populations have declined in mature forests of western North America. They are classified as three subspecies: California, northern, and Mexican. Northern and Mexican spotted owls are listed as threatened under the U.S. Endangered Species Act, and California spotted owls are not. In partnership with many others, the USGS has been collecting and analyzing information about spotted owl genetics for over a decade. The distinction of the northern spotted owl as separate subspecies from California and Mexican spotted owls has been reaffirmed. Genetic information also indicates a zone of mixing between northern and California spotted owls in a portion of southern Oregon. This suggests that the range of California spotted owls extends farther north than previously described. Management agencies used these and other genetic information to review the status of the northern spotted owl, and in combination with population estimates and habitat assessments, to consider management options for all three subspecies.

For more information view http://fresc.usgs.gov/research/StudyDetail.asp?Study_ID=46 and contact Susan M. Haig, Forest and Rangeland Ecosystem Science Center.

Barred owl in a tree along Skyline Drive. Photo credit: Eric Butler, NPS

Northern spotted owls are hybridizing with barred owls in the Pacific Northwest, and the offspring can be difficult to distinguish from either parent species. From management, law enforcement, and research perspectives, it is important to be able to determine whether a specimen is a northern spotted owl, (a species listed under the Endangered Species Act), a barred owl (protected under the Migratory Bird Treaty Act), or a hybrid (protected under the Migratory Bird Treaty Act). The USGS has worked with the U.S. Forest Service and the U.S. Fish and Wildlife Service to assess maternal and bi-parental gene flow in the process of hybridization between northern spotted owls and barred owls. The results indicate that hybrids have unique genetic combinations, including distinct markers from both parents. The analyses also corroborate the findings of many field studies, which have indicated that most hybrids result from crosses between female barred owls and male spotted owls. These genetic markers allow scientists and managers to clearly identify these species as well as hybrids, and provide solid evidence needed in law enforcement cases.

For more information view http://fresc.usgs.gov/research/StudyDetail.asp?Study_ID=298 and contact Susan M. Haig, Forest and Rangeland Ecosystem Science Center.

Trumpeter swans. Photo credit: Copyright Phil Myers, Museum of Zoology, University of Michigan, courtesy of Animal Diversity Web

For management purposes, the range of naturally occurring trumpeter swans (Cygnus buccinator) has been divided into two populations, the Pacific Coast Population (PP) and the Rocky Mountain Population (RMP). Little is known about the distribution of genetic variation across the species’ range despite increasing pressure to make difficult management decisions regarding the two populations and flocks within them. To address this issue, USGS scientists used rapidly evolving genetic markers to elucidate the underlying genetic structure of the species. Genetic data revealed a significant difference between the two populations, with the Yukon Territory as a geographic area of mixing and population overlap. Additionally, they found that both populations have somewhat similar levels of genetic diversity (PP is slightly higher), suggesting that the PP underwent a population bottleneck similar to a well-documented one in the RMP. Both genetic structure and diversity results reveal that the Tri-State flock, a suspected unique, non-migratory flock, is not genetically different from the Canadian flock of the RMP and need not be treated as a unique population from a genetic standpoint. Finally, trumpeter swans appear to have much lower mitochondrial DNA variability than other waterfowl studied thus far, which suggests a previous, species-wide bottleneck.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.

White-tailed ptarmigan. Photo credit: Copyright Steve Hinshaw, courtesy of Animal Diversity Web

Investigation into the interaction between ecological and evolutionary responses to global change is an important aspect of climate change studies. To address this issue, USGS scientists are documenting changes in genetic diversity and allele frequencies in white-tailed ptarmigan from Mt. Evans, Colo., over a 40-year time span and also are comparing current levels of diversity and patterns of allele frequencies with a northern population on Vancouver Island, British Columbia. Further, they are attempting to identify genetic markers under selection and to determine whether these markers can be correlated with environmental changes associated with climate change, as an understanding of the genetic basis of phenotypes under selection allows for the prediction and mitigation of the effects of climate change on the viability of populations.

For more information contact Sara J. Oyler-McCance, Rocky Mountain Center for Conservation Genetics and Systematics.