Search USGS⌕ Search

Geology topics

D. H. Ellis

Publications and source records attributed to D. H. Ellis.

At least 109 records · Page 6Linked to original sources
USGS1988

Crested caracara

The crested caracara's range extends from the southern United States south to Tierra del Fuego. Although the caracara has been recorded in all of the southwestern states, it occurs regularly only in southern Arizona and central, southern and coastal Texas. Its distribution is closely linked to the availability of carrion. Throughout its range, thecaracara is associated with open habitats such as desertscrub, grassland and savanna. Nesting pairs usually produce one brood each breeding season, which extends from December through August. Eggs are laid from March into early June and clutch size averages two to three eggs. Young fledge in June and July and may remain with the adults for several weeks. Management recommendations for the crested caracara include clarifying its status in the Southwest. using supplemental feeding and modifying habitats to encourage recolonization of previously occupied areas and movement into new areas.

Book chapter↗
USGS1988

Ferruginous hawk

In the Southwest, the ferruginous hawk is a local and isolated breeder and an uncommon but consistent winter visitor. Apparently, the breeding range of this species in the Southwest was historically much greater than today. The ferruginous hawk is being considered for listing by the U.S. Fish and Wildlife Service but remains unclassified by the individual states comprising the Southwest region. Habitat and diet information is summarized. Nest location and structure, breeding, and wintering biology are also discussed. Long-term and seasonal monitoring is conducted annually at several nest locations in New Mexico, while documented reproductive efforts in Arizona, Texas and Oklahoma are extremely rare and isolated. Research and management recommendations include population and habitat surveys, dietary and reproductive investigations, and habitat protection.

Book chapter↗
USGS1988

Raptors and aircraft

Less than 5% of all bird strikes of aircraft are by raptor species, but damage to airframe structure or jet engine dysfunction are likely consequences. Beneficial aircraft-raptor interactions include the use of raptor species to frighten unwanted birds from airport areas and the use of aircraft to census raptor species. Many interactions, however, modify the raptor?s immediate behavior and some may decrease reproduction of sensitive species. Raptors may respond to aircraft stimuli by exhibiting alarm, increased heart rate, flushing or fleeing and occasionally by directly attacking intruding aircraft. To date, most studies reveal that raptor responses to aircraft are brief and do not limit reproduction; however, additional study is needed.

Book chapter↗
USGS1988

Peregrine falcon

Since 1975, 101 peregrine falcon breeding sites have been documented in Arizona, New Mexico and western Texas. Eyries were found in either riverine or montane canyons, habitats which supported dense and diverse avian prey and provided structural characteristics that may increase prey vulnerability. Approximately 85% of the sites visited each year were occupied. Egg-laying (mid-February to mid-May) typically occurred first in the south and at lower elevations, and later in the north and at higher elevations. Mean productivity of adult pairs (mean =1.55 young/year) was comparable to rates reported for healthy populations. Poor productivity and decreased territorial occupancy in western Texas and southeastern New Mexico occurred in the presence of high levels of environmental DDE. Estimates of the breeding population (141-187 occupied territories) are twice the U.S. Fish and Wildlife Service (USFWS) recovery goal for the region; however, the population is not considered recovered. The discrepancy of these assessments stems from the suitable-habitat approach used by the authors vs. the narrower eyrie-based USFWS recovery plan. Recommendations include reevaluation of recovery goals to ensure adequate habitat protection, elimination of regional sources of organochlorine pesticides, delineation of suitable habitat, formulation of habitat management prescriptions, winter habitat studies,continued monitoring of territorial occupancy and productivity, and accountability for sensitive information.

Book chapter↗
USGS1986

An overview of raptor conservation in Latin America

Prior to the last decade, biological studies of raptorial birds in Latin America were almost nonexistent. For many species little more was known than their general range and habitat type. The last few years have seen the opening of a door to what will surely be a flood of scientific investigations. Ultimately, the survival of raptor communities in Latin America depends not only on research but also on several other equally significant conservation efforts. These typically appear in the following order: first, appropriate legislation must be enacted and enforced to provide legal protection; second, the public must be educated concerning the value of wildlife; third, substantial blocks of favourable habitat must be identified and preserved; fourth, economic incentives must be generated so that the local human populations actually benefit from the preservation of vulnerable wildlife and natural habitats; and finally, the long-term success of all of these efforts in each nation depends on the attainment of political, economic and social stability.

Birds of Prey Bulletin↗
USGS1986

Domingo's story

Explore the source record for details and available documents.

North American Falconers Association Journal↗
USGS1985

The Andean condor as a research surrogate for the California condor

Captive propagation of Andean Condors ( Vultur gryphus ) was initiated at the Patuxent Wildlife Research Center in 1966 in anticipation of the need to apply resulting techniques to the captive breeding of the endangered California Condor ( Gymnogyps californianus ). This report summarizes the progress made on this Andean Condor breeding and research project, with emphasis on recent fostering/cross-fostering studies. These studies include: (a) fostering eggs/chicks between Andean Condors; (b) fostering of two chicks each to Andean Condor pairs; (c) cross-fostering of a Turkey Vulture ( Cathartes aura ) to Andean Condors; and (d) cross-fostering an Andean Condor chick to wild California Condors. Implications of these studies for the recovery of the California Condor will be discussed.

Book chapter↗
USGS1985

Productivity, pesticides, and management of the Peregrine Falcon in Arizona

In the decade since research commenced with the Peregrine in Arizona, over 60 sites have been identified which historically or presently are occupied by breeding pairs. Productivity was determined for about 120 breeding attempts from 1975-85. Almost all sites, for which productivity information is available for two or more years, have hatched young. Average values for fledging success were ca. 1.4 young/attempt for all active sites and ca. 2.3 young/attempt for successful sites. Eggshell thickness values were highly varied, but few samples reflect thinning sufficient to cause reproductive failure, and the population appears to be increasing slightly. Management practices which can further benefit the falcon include: controlling pesticide use, habitat protection, and information management.

Book chapter↗
USGS1985

An overview of raptor biology and conservation in Latin America

Prior to the last decade, biological studies of raptorial birds in Latin America were, with a few exceptions, nonexistent. For many species all that was known was the general range and habitat type. While the logistical and political challenges are still present, the last few years has seen the opening of a door to what will almost surely be a flood of scientific investigations. From over 40,000 ground miles traveled in 16 countries, field contact with over two thirds of the raptor species, and interviews with conservation officers in 10 nations, I will report on some raptor concentration areas, identify topics for future research, and generalize on raptor conservation issues. I will also briefly mention some recent biological studies and touch briefly on the challenges awaiting the biologist who tries his or her hand at reaping the rewards that are present in abundance for those who engage in raptor studies in Latin America.

Book chapter↗