Geology topics

Martha A. Hatch

Publications and source records attributed to Martha A. Hatch.

6 recordsLinked to original sources

USGS1990

Breeding seasons of oceanic birds in a subarctic colony

We studied the breeding seasons of marine birds on the Semidi Islands, western Gulf of Alaska, from 1976 to 1983. Distributions of laying or hatching observed in 11 species during 1–7 years are presented; less detailed information is available on the breeding schedules of three species. The combined laying period of 14 species lasted 3 months from mid-April to mid-July; the first eggs of the earliest and latest species were laid about 9 weeks apart. Mean laying dates varied by 2–16 days in nine species observed in 2 or more years. Although the egg-laying sequence of species was largely preserved from year to year, we found little evidence of concordant annual variation in breeding seasons. Species that fed lower in the food chain tended to breed earlier than those that fed at higher trophic levels. Early laying was correlated with longer laying periods, both within and between species. With the exception of three puffin species, birds with similar food habits exhibited less overlap in hatching and fledging dates than laying dates. A test for nonrandom dispersion of breeding times failed to find evidence for competitive avoidance of breeding overlap in piscivores or planktivores. Species may not have timed their egg laying to provide for maximum food availability during chick rearing. Rather, the comparative analysis of breeding schedules suggests that breeding times were determined more by the food requirements of laying females. Young females laying relatively late probably account for the right-skewed distributions of egg laying observed in this and other studies of colonial seabirds.

Alaska↗

USGS1990

Components of breeding productivity in a marine bird community: key factors and concordance

We estimated components of annual breeding productivity for eight species of marine birds on the Semidi Islands in the western Gulf of Alaska. Mortality of eggs and young, caused primarily by avian predators, accounted for most of the annual variation in productivity. Failure to produce eggs, clutch size variation, and the hatchability of eggs were generally less important. The stage of breeding at which annual productivity was most strongly regulated differed among species. In murres, chick-rearing success accounted for the largest share of annual variation in overall productivity, whereas incubation success was the key factor in fulmars, kittiwakes, and puffins. Although avian predators were the dominant proximate cause of egg and chick losses in some species, food supply seemed ultimately responsible for variation in all the major components of productivity. Concordance of productivity among species was low for the marine bird community as a whole, but selected pairs of species exhibited a greater tendency for high and low productivities to occur in the same years. Compared with the same or similar species outside Alaska, Semidi Islands birds were in one of three categories: ( i ) species whose productivity was about the same as reported from other areas (fulmars and gulls), ( ii ) species with comparatively low productivity (murres, puffins, kittiwakes), and ( iii ) species with similar mean productivity but greater annual variation (cormorants). These patterns suggest that specialized consumers of forage fish experienced food shortages at the Semidi Islands and that surface feeders were more severely affected than divers.

Alaska↗

USGS1989

Attendance patterns of murres at breeding sites: Implications for monitoring

We studied attendance patterns (presence and absence at breeding sites) of common murres ( Uria aalge ) and thick-billed murres ( U. lomvia ) at a colony in the Semidi Islands, western Gulf of Alaska. The period from mid-laying through hatching was appropriate for censusing because counts were subject to the least amount of daily variation. Time of day and weather did not have large effects on the counts and serial dependence was weak or absent. A trend in murre numbers during the census period occurred in 2 of 4 years but the direction of change was inconsistent. Counts made on 40 consecutive days were needed to detect a 6-8% change in numbers between years, whereas 5 counts were adequate to detect a 20-26% change in numbers. Annual changes in murre numbers varied among study plots but mean combined counts differed by 6-16% between years. Behavioral differences alone were inadequate to explain the annual variation in plot counts because site occupancy rates of individual murres were relatively constant.

Alaska↗

USGS1988

Colony attendance and population monitoring of Black-legged Kittiwakes on the Semidi Islands, Alaska

Patterns of colony attendance in Black-legged Kittiwakes ( Rissa tridactyla ) were studied over 5 years on the Semidi Islands, western Gulf of Alaska. A census period of 50 days, extending from first egg laying through final hatching, was appropriate because counts made then were subject to the least amount of daily variation. Five counts during that period were sufficient to detect a 25% change in numbers between years; counts made on all 50 days of the census period would detect a 5 to 7% change. There was little evidence for seasonal trends or serial correlation of counts during the census period, but attendance was negatively correlated with wind speed. Half of an apparent 17% increase in population between 1980 and 1981 was due to birds spending more time at their nest sites in the latter year, thereby increasing the mean of attendance counts. Despite such difficulties in the interpretation of attendance counts, birds were considered to be better counting units for population monitoring than nests, because nest densities were subject to large annual fluctuations in breeding effort.

Alaska↗

USGS1983

Populations and habitat use of marine birds in the Semidi Islands, Alaska

About one-quarter of the resident seabirds in the Gulf of Alaska breed on the Semidi Islands. In terms of biomass, the proportion is closer to one-third. The most abundant birds are Common and Thick-billed Murres, with a combined population exceeding 1 million birds. Hundreds of thousands of Horned Puffins breed in burrows on two islands. Other species numbering more than 100,000 individuals include the Northern Fulmar, Fork-tailed and Leach's Storm-Petrels, and possibly also the Black-legged Kittiwake and Tufted Puffin. Both species of storm-petrels commonly nest in side chambers of puffin burrows. Parasitic Jaegers nest in a loose colony on Chowiet Island. This behavior has not been reported elsewhere in the Gulf of Alaska. Red-faced and Pelagic Cormorants commonly change breeding colony location from year to year. The Semidi Islands are the easternmost breeding site for Least Auklets.

Alaska↗

USGS1983

An isolated population of small Canada geese on Kaliktagik Island, Alaska

Recently we discovered that a small form of the Canada Goose Branta canadensis breeds on Kaliktagik Island, one of the Semidi Islands, about 80 km south of the Alaska Peninsula near longitude 157°W (Figure 1). The unexpected occurrence of geese on this oceanic island and the possibility that they are closely allied with the endangered Aleutian race of Canada Geese B. c. leucopareia prompt this summary of observations made between 1977 and 1981, in the course of field studies on seabirds of the area.

Alaska↗