15 research outputs found
Long-term monitoring of Scripps’s Murrelet and Guadalupe Murrelet at San Clemente Island, California: evaluation of baseline data in 2012–2016
San Clemente Island (SCI) supports one of the smallest Scripps’s Murrelet (Synthliboramphus scrippsi; SCMU) colonies in the world, and perhaps the only colony of Guadalupe Murrelets (S. hypoleucus; GUMU) in California. In 2012–2016, the U.S. Navy sponsored development of a long-term murrelet monitoring program at SCI that utilized nocturnal spotlight surveys, night-lighting at-sea captures, and nest monitoring. Standardized spotlight survey transects were established in nearshore waters off breeding areas at Seal Cove and southeast SCI (SESCI). Baseline mean spotlight counts were 29 ± 15 murrelets (n = 31) at Seal Cove in 2013–2016 and 21 ± 10 murrelets (n = 15) at SESCI in 2014–2016. We banded 201 SCMU captured in congregations at Seal Cove (n = 158) and SESCI (n = 43); 12% of the SCMU from Seal Cove and 7% from SESCI were recaptured ≥1 year after banding. We also banded 21 GUMU at Seal Cove, but none were recaptured. Murrelet nests or eggs were found in 6 shoreline breeding “refuges” at Seal Cove and SESCI that were seldom if ever visited by island foxes (Urocyon littoralis clementae) and feral cats (Felis catus). Incubating SCMU were observed in 4 nest sites, but in 8 other sites only eggs or eggshells were found. Overall hatching success was very low (12%; n = 17 clutches) in 2012–2016, apparently due to intraspecific competition for limited nest crevices at Seal Cove and predation (or possibly abandonment and subsequent egg scavenging) by foxes or black rats (Rattus rattus) at SESCI. Using spotlight survey data, we estimated 115 murrelet pairs (range 79–208) at SCI, including 110 pairs (range 76–199) of SCMU and 5 pairs (range 3–9) of GUMU, although a GUMU nest has not yet been found. Power analyses of Seal Cove spotlight data indicated that surveys conducted over 9 nights per year for 20 years could reliably (power ≥ 0.90) detect minimum population changes of ± 1.7% per annum. Additional efforts are needed to (1) confirm the breeding status of GUMU; (2) investigate alternative methods of rat control to increase hatching success in murrelet breeding refuges; and (3) enhance breeding habitats to reduce intraspecific competition for nest sites and increase the number of monitored nests
Scripps's Murrelet at San Miguel Island, California: Status of a Small Population at the Northwest Limit of the Breeding Range
Breeding of the Leach\u27s Storm-petrel Oceanodroma Leucorhoa at Santa Catalina Island, California
Occurrence, Morphometrics and Plumage Variability Among Leach\u27s Storm-petrels Oceanodroma Leucorhoa in the California Channel Islands, 1976-2015
Internationale Unternehmensbesteuerung : Handbuch zur Besteuerung internationaler Unternehmen mit Auslandsbeziehungen
San Clemente Island (SCI) supports one of the smallest Scripps’s Murrelet (Synthliboramphus scrippsi; SCMU) colonies in the world, and perhaps the only colony of Guadalupe Murrelets (S. hypoleucus; GUMU) in California. In 2012–2016, the U.S. Navy sponsored development of a long-term murrelet monitoring program at SCI that utilized nocturnal spotlight surveys, night-lighting at-sea captures, and nest monitoring. Standardized spotlight survey transects were established in nearshore waters off breeding areas at Seal Cove and southeast SCI (SESCI). Baseline mean spot- light counts were 29 ± 15 murrelets (n = 31) at Seal Cove in 2013–2016 and 21 ± 10 murrelets (n = 15) at SESCI in 2014–2016. We banded 201 SCMU captured in congregations at Seal Cove (n = 158) and SESCI (n = 43); 12% of the SCMU from Seal Cove and 7% from SESCI were recaptured ≥1 year after banding. We also banded 21 GUMU at Seal Cove, but none were recaptured. Murrelet nests or eggs were found in 6 shoreline breeding “refuges” at Seal Cove and SESCI that were seldom if ever visited by island foxes (Urocyon littoralis clementae) and feral cats (Felis catus). Incubating SCMU were observed in 4 nest sites, but in 8 other sites only eggs or eggshells were found. Overall hatching success was very low (12%; n = 17 clutches) in 2012–2016, apparently due to intraspecific competition for limited nest crevices at Seal Cove and predation (or possibly abandonment and subsequent egg scavenging) by foxes or black rats (Rattus rattus) at SESCI. Using spotlight survey data, we estimated 115 murrelet pairs (range 79–208) at SCI, including 110 pairs (range 76–199) of SCMU and 5 pairs (range 3–9) of GUMU, although a GUMU nest has not yet been found. Power analyses of Seal Cove spotlight data indicated that surveys conducted over 9 nights per year for 20 years could reliably (power ≥ 0.90) detect minimum population changes of ±1.7% per annum. Additional efforts are needed to (1) confirm the breeding status of GUMU; (2) investigate alternative methods of rat control to increase hatching success in murrelet breeding refuges; and (3) enhance breeding habitats to reduce intraspecific competition for nest sites and increase the number of monitored nests.
La isla San Clemente (SCI, por sus siglas en inglĂ©s) aloja a una de las colonias de mĂ©rgulos de Scripps (Synthliboramphus scrippsi; SCMU) más pequeñas del mundo, y tal vez la Ăşnica colonia de mĂ©rgulos californianos aliclaros (S. hypoleucus; GUMU) en California. Entre los años 2012–2016, la Marina de los EE.UU. patrocinĂł el desarrollo de un programa a largo plazo de monitoreo de mĂ©rgulos en la Isla San Clemente, apoyándose de muestreos nocturnos, capturas en el mar mediante iluminaciĂłn y monitoreo de nidos. Se establecieron muestreos en transectos estandarizados en zonas cercanas a la costa, fuera de las áreas de crianza, en Seal Cove y el sudeste de la Isla San Clemente (SESCI, por sus siglas en inglĂ©s). El nĂşmero promedio fue de 29 ± 15 mĂ©rgulos (n = 31) en Seal Cove entre 2013–2016, y de 21 ± 10 mĂ©rgulos (n = 15) en SESCI entre 2014–2016. Anillamos 201 mĂ©rgulos de Scripps que fueron capturados en grupos en Seal Cove (n = 158) y SESCI (n = 43), el 12% de los mĂ©rgulos de Seal Cove y el 7% de los de SESCI fueron recapturados ≥1 año despuĂ©s de haber sido anillados. AsĂ mismo, anillamos 21 mĂ©rgulos californianos aliclaros en Seal Cove, pero ninguno fue recapturado. Encontramos nidos y/o huevos de mĂ©rgulos en 6 “refugios” de reproducciĂłn cercanos a la costa en Seal Cove y en el sudeste de la Isla San Clemente, que parecen ofrecer protecciĂłn contra el zorro isleño (Urocyon littoralis clementae) y el gato domestico (Felis catus). Observarmos mĂ©rgulos de Scripps incubando 4 nidos, pero sĂłlo encontramos huevos o cáscaras de huevos en otros 8 sitios. El Ă©xito de eclosiĂłn total fue muy bajo (12%, n = 17 puestas) en 2012–2016, aposiblemnete debido a la competencia intra-especĂfica por el nĂşmero limitado de grietas para el establecimiento de nidos en Seal Cove y por la depredaciĂłn (o el posible abandono y posterior consumo de huevos) por ratas negras (Rattus rattus) en SESCI. Utilizando los datos de los muestreos, estimamos 115 parejas de mĂ©rgulos (rango 79–208) en la Isla San Clemente, incluidos 110 parejas (rango 76–199) de mĂ©rgulos de Scripps y 5 parejas (rango 3–9) de mĂ©rgulos californianos aliclaros, aunque aĂşn no se encontraron nidos de estos Ăşltimos