Geology topics

C. L. Gratto-Trevor

Publications and source records attributed to C. L. Gratto-Trevor.

5 recordsLinked to original sources

USGS2010

Subspecies status and population genetic structure in Piping Plover ( Charadrius melodus )

Piping Plover (Charadrius melodus) is a migratory shorebird that is listed as endangered in Canada and the U.S. Great Lakes and as threatened throughout the rest of its breeding and winter range. We undertook a comprehensive molecular-genetic investigation to (1) address subspecific taxonomy, (2) characterize population genetic structure, and (3) infer past bottlenecks and demographic processes in this species. Analyses included individuals from 23 U.S. states and Canadian provinces and were based on mitochondrial DNA sequences (580 base pairs, n = 245) and 8 nuclear microsatellite loci (n = 229). Our findings provide support for separate Atlantic and Interior subspecies (C. m. melodus and C. m. circumcinctus, respectively). Birds from the Great Lakes region were allied with the Interior subspecies and should be referred to as C. m. circumcinctus. Population genetic analyses illustrated stronger genetic structure among Atlantic than among Interior birds, which may reflect reduced natal- and breeding-site fidelity of Interior individuals. Furthermore, analyses suggested that Interior birds previously experienced genetic bottlenecks, whereas there was no evidence of such patterns in the Atlantic subspecies. We interpret these results in light of 25 years of range-wide census data. Overall, differences between Interior and Atlantic Piping Plovers may reflect differences in spatiotemporal stability of nesting habitat between regions. ?? 2010 The American Ornithologists' Union.

The Auk↗

USGS2006

Fat dynamics of arctic-nesting sandpipers during spring in mid-continental North America

We measured fresh body mass, total body fat, and fat-free dry mass (FFDM) of three species of Arctic-nesting calidrid sandpipers (Baird's Sandpiper [ Calidris bairdii ], hereafter “BASA”; Semipalmated Sandpiper [ C. pusilla ], hereafter “SESA”; and White-rumped Sandpiper [ C. fuscicollis ], hereafter “WRSA”) during spring stopovers in the Prairie Pothole Region (PPR) of North Dakota, and evaluated the contribution of stored fat to (1) energy requirements for migration to their Arctic-breeding grounds and (2) nutrient needs for reproduction. All spring migrant WRSA ( n = 124) and BASA ( n = 111), and all but 2 of 99 SESA we collected were ≥2 years old. Male and female BASA migrated through North Dakota concurrently, male SESA averaged earlier than females, and WRSA males preceded females. Fat indices (ratio of fat to FFDM) of male and female SESA and WRSA averaged approximately twice those of male and female BASA. Total body fat of male and female BASA increased with date in spring 1980, but not in 1981; slopes were similar for both sexes each year. Male and female SESA arrived lean in 1980 and 1981, and total body fat increased with date in both years, with similar slopes for all combinations of sex and year. Male and female WRSA arrived lean in 1980–1981 and 1981, respectively, and total body fat increased with date, whereas females arrived with fat reserves already acquired in 1980. Interspecific and sex differences in migration schedules probably contributed to variation in fat storage patterns by affecting maintenance energy costs and food availability. Estimated flight ranges of BASA suggest that few could have met their energy needs for migration to the breeding grounds exclusively from fat stored by the time of departure from North Dakota. Estimated flight ranges of SESA and WRSA, along with fresh body masses of both species when live-trapped on or near their breeding grounds in northern Canada, suggest that major parts of both populations stored adequate fat by departure from temperate mid-continental North America to meet their energy requirements for migration and part of their nutrient needs for reproduction.

The Auk↗

USGS2003

Population identification of western hemisphere shorebirds throughout the annual cycle

Identification of relationships among geographically distinct populations of migratory species can provide an understanding of breeding and natal philopatry, migration pathways, and population mixing during winter. We used random amplified polymorphic DNA (RAPD) analyses to search for markers specific to difficult‐to‐differentiate shorebird species (e.g. long‐billed dowitcher Limnodromus scolopaceus and short‐billed dowitcher L. griseus ) as well as geographically distinct breeding populations of Hudsonian godwits Limosa haemastica , red‐necked phalaropes Phalaropus lobatus , semipalmated plovers Charadrius semipalmatus , dunlin Calidris alpina , pectoral sandpipers C. melanotos , semipalmated sandpipers C. pusilla and western sandpipers C. mauri . Markers clearly differentiated all shorebird species. Estimates of population differentiation varied greatly among species ( F ST = 0.095–0.685) and correlated with interspecific variation in philopatry and geographical separation of breeding populations. We assigned individuals to putative breeding locales with greater certainty in well‐differentiated species than in poorly differentiated species. Our findings indicate specific phylogeographical structure varies among species, which has strong implications for conservation of habitats within migratory corridors. We suggest that RAPDs are useful in identifying geographical populations of migratory species and that molecular markers should be considered for tracking migratory birds throughout the annual cycle.

Molecular Ecology↗

USGS2001

Estimates of shorebird populations in North America

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fall in the range of hundreds of thousands, particularly the low hundreds of thousands; estimated population sizes for large shorebird species currently all fall below 500 000. Population size is inversely related to size (mass) of the species, with a statistically significant negative regression between log(population size) and log(mass). Two outlying groups are evident on the regression graph: one, with populations lower than predicted, includes species considered to be either “at risk” or particularly hard to count, and a second, with populations higher than predicted, includes two species that are hunted. Shorebird population sizes were derived from data obtained by a variety of methods from breeding, migration, and wintering areas, and formal assessments of accuracy of counts or estimates are rarely available. Accurate estimates exist only for a few species that have been the subject of detailed investigation, and the likely accuracy of most estimates is considered poor or low. Population estimates are an integral part of conservation plans being developed for shorebirds in the United States and Canada and may be used to identify areas of key international and regional importance.

Occasional Paper of the Canadian Wildlife Service↗

USGS2000

Population estimates of Nearctic shorebirds

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Shorebird population sizes were derived from data obtained by a variety of methods from breeding, migration and wintering areas, and formal assessments of accuracy of counts or estimates are rarely available. Accurate estimates exist only for a few species that have been the subject of detailed investigation, and the likely accuracy of most estimates is considered poor or low. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fell in the range of hundreds of thousands, particularly the low hundreds of thousands; estimated population sizes for large shorebird species currently all fall below 500,000. Population size was inversely related to size (mass) of the species, with a statistically significant negative regression between log (population size) and log (mass). Two outlying groups were evident on the regression graph: one, with populations lower than predicted, included species considered either to be "at risk" or particularly hard to count, and a second, with populations higher than predicted, included two species that are hunted. Population estimates are an integral part of conservation plans being developed for shorebirds in the United States and Canada, and may be used to identify areas of key international and regional importance.

Waterbirds↗