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At least 865 records · Page 48Linked to original sources
USGS1971

Population ecology of the great blue heron with special reference to western Oregon

Great Blue Heron (Ardea herodias) begin nesting in western Oregon about 1 month earlier than reported from the Philadelphia region and about 2 months earlier than reported from Southern Alberta. The number of young fledged per nesting pair in Oregon was 2.04 in 1970 which was nearly identical to the 1.91 believed necessary to maintain a stable population in the northern United States. The level of p,p'DDE reported from two eggs in Oregon was within the same range as that reported from 40 eggs in Alberta. Although some thin-shelled eggs were being laid in Alberta, the observed production was believed sufficient for maintaining a stable population. Production rates reported from a heronry in central California suggested that the population there was also remaining fairly stable.

Canadian Field-Naturalist↗
USGS1976

Mapping wetlands on beaver flowages with 35-mm photography

Beaver flowages and associated wetlands on the Chippewa National Forest, north-central Minnesota, were photographed from the ground and from the open side window of a small high-wing monoplane. The 35-mm High Speed Ektachrome transparencies obtained were used to map the cover-type associations visible on the aerial photographs. Nearly vertical aerial photos were rectified by projecting the slides onto a base map consisting ofcontrol points located by plane-table survey. Maps were prepared by tracing the recognizable stands of vegetation in the rectified projection at the desired map scale. Final map scales ranging from 1:260 to 1:571 permitted identification and mapping of 26 cover-type associations on 10 study flowages in 1971. This cover-mapping technique was economical and substituted for detailed ground surveys. Comparative data from 10 flowages were collected serially throughout the entire open-water season. Although developed for analysis of waterfowl habitat, the technique has application to other areas of wildlife management and ecological investigation.

Canadian Field-Naturalist↗
USGS1956

Toxicity of chlorinated insecticides to quail and pheasants

'Residues from insecticidal applications of chlorinated hydrocarbons may remain toxic for extended periods. In experiments designed to furnish information on the effects upon quail and pheasants of prolonged feeding upon diets containing small percentages of these compounds, it was shown that aldrin, dieldrin and endrin are cumulative, and that quail are unable to survive after ingesting 5-10 mg./kg, of aldrin, 30-50 mg./kg, of dieldrin, or 6-15 mg./kg, of endrin. Maximum levels (p.p.m.) in the diets permitting survival for extended periods were: DDT, 200; strobane, above 500; aldrin, 0.5; dieldrin, 1.0; endrin, 1.0. Inclusion of these compounds in the diets of breeding quail and pheasants affected hatchability of eggs and viability of chicks, even though the adult birds appeared unaffected.' Detailed figures are given for all points mentioned.

Atlantic Naturalist↗