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H.R. Carter

Publications and source records attributed to H.R. Carter.

6 recordsLinked to original sources
USGS2007

At-sea distribution and abundance of seabirds off southern California: A 20-year comparison

We conducted aerial at-sea and coastal surveys to examine the distribution and abundance of seabirds off southern California, from Cambria, California, to the Mexican border. From May 1999-January 2002, we flew 102 d, covered >54,640 km of transect lines, and conducted nine complete surveys of southern California in January, May, and September. We identified 54 species comprising 12 families and counted >135,000 individuals. Seabird densities were greater along island and mainland coastlines than at sea and were usually greatest in January surveys. Densities were greatest at sea near the northern Channel Islands in January and north of Point Conception in May, and lowest in the southwestern portion of the Southern California Bight in all survey months. On coastal transects, seabird densities were greatest along central and southern portions of the mainland coastline from Point Arguello to Mexico. We estimated that 981,000 ?? 144,000 (x?? ?? SE) seabirds occurred in the study area in January, 862,000 ?? 95,000 in May, and 762,000 ?? 72,000 in September. California Gulls (Larus californicus), Western Grebes (Aechmophorus occidentalis), and Cassin's Auklets (Ptychoramphus aleuticus) were most abundant in January surveys at sea, whereas Sooty and Short-tailed shearwaters (Puffinus griseus and P. tenuirostris), phalaropes (Phalaropus spp.), and Western Gulls (Larus. occidentalis) were most abundant in May and September surveys. On coastal transects, California Gulls, Western Grebes, Western Gulls, and Surf Scoters (Melanitta perspicillata) were most abundant in January; Western Grebes, Western Gulls, Surf Scoters, and Brown Pelicans (Pelecanus occidentalis) were most abundant in May; and Sooty Shearwaters, Short-tailed Shearwaters, Western Gulls, Western Grebes, Brown Pelicans, and Heermann's Gulls (Larus heermanni) were most abundant in September. Compared to historical seabird densities collected in the same area two decades ago (1975-1978 and 1980-1983), abundance was lower by 14% in January, 57% in May, and 42% in September. Common Murres (Uria aalge, ???75% in each season), Sooty Shearwaters (55% in May, 27% in September), and Bonaparte's Gulls (L. Philadelphia, ???95% in each season) had lower densities. Conversely, Brown Pelicans (167% overall), Xantus's Murrelets (Synthliboramphus hypoleucus; 125% overall), Cassin's Auklets (100% overall), Ashy Storm-Petrels (Oceanodroma homochroa, 450% overall) and Western Gulls (55% in May), and Brandt's Cormorants (Phalacrocorax penicillatus, 450% in September) had greater densities. Our results indicate that seabird abundance has declined off the southern California coast in the past two decades, and these declines may be warning signs of environmental degradation in the region or effects of larger forces such as climate change.

Studies in Avian Biology↗
USGS2003

Radio-telemetry evidence of re-nesting in the same season by the Marbled Murrelet

Unlike other alcids, laying of replacement eggs has not been well documented in Brachyramphus murrelets. Observations of two radio-marked Marbled Murrelets ( Brachyramphus marmoratus ) in northern California during 2001 and 2002 suggested that they can re-lay in the same breeding season. In 2001, aircraft telemetry first detected a male Marbled Murrelet at a forested inland location on 17 May. This bird alternated 24h incubation bouts with 24h at sea periods until 29 May, when data logger recordings indicated that the bird arrived at the nest at 05.17 h (PDT), but left at 05.32 h. This nesting effort had apparently failed. Sixteen days later, on 14 June this murrelet arrived in the vicinity of the first nest site at 05.19 h and remained there until 18.57 h that same evening and then left. We suspected that this event represented a second breeding effort that also failed, either near or at the site of the first effort. In 2002 a female Marbled Murrelet, first detected inland on 13 June by aircraft telemetry, alternated on the nest one day and at sea the next until 23 June when the breeding effort is presumed to have failed. This bird was again detected inland on 21 July, and alternated on the nest one day and at sea the following day until 3 August, when the radio-transmitter fell off the bird. Video recordings at the nest site indicated this second nesting attempt continued until 1 September, when the chick died of unknown causes. As in other alcids, re-laying apparently occurred 2-4 weeks after failure of the first eggs, either near or at the site of first eggs. Re-nesting may be frequent in murrelets, given the high rates of breeding failure reported.

California↗
USGS1997

Oiled seabird rescue at the J.V. Fitzgerald Marine Reserve, San Mateo County, California, 1968-1995

Records of oiled and injured seabirds at the J.V. Fitzgerald Marine Reserve, San Mateo County, California, were collated from the daily log at the Reserve for the period 1968-1995. These records serve to demonstrate that oil spills and chronic oiling have occurred frequently in this area, just south of San Francisco. Common Murres (Uria aalge) were the most frequently-oiled species rescued at the Reserve. Greater efforts should be made by wildlife rehabilitators to collate large volumes of past data (prior to the early 1990s) on oiled and injured seabirds for similar documentation of large or moderate oil spills (including undocumented or poorly-known spills), chronic oiling from small spills, and injuries from other sources.

Journal of Wildlife Rehabilitation↗
USGS1988

Effects of the 1982-83 El Niño – Southern Oscillation on Pacific Ocean bird populations

Seabird reproductive success, population size, and movements in the Pacific region responded dramatically to the 1982-83 El Niño – Southern Oscillation (ENSO). At sites within the North and South Pacific Gyres, the onset of seabird responses tracked oceanographic changes related to ENSO; to the north of the gyres, responses were delayed 1 yr. Reproductive failures and high adult mortality were detected at all sites investigated. Post-ENSO, the return to “normal” nesting patterns depended on species and locality. The 1982-83 ENSO revealed a dimension to the variability in seabird reproductive biology only now appreciated by ornithologists.

Conference Paper↗