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At least 505 records · Page 28Linked to original sources
USGS1996

Productivity of the spruce grouse in fragmented habitat at the edge of its range

We measured productivity of the Spruce Grouse (Dendragapusc anadensicsa nadensis) in patchy black spruce (Picea mariana) habitat along the southeastern limit of its range in mid-coastal Maine. We captured grouse and attached necklace-mounted radio transmitters to hens prior to nesting. Of 19 females monitored, only 26% raised chicks to the late brood-rearing period. Predation was high on hens (37%) and five were killed before hatching eggs. Six (55%) entire broods were lost and only 30% of chicks survived to late summer. Production ( No. of chicks/female), an index of productivity, was < 1 and lower in Maine and Minnesota study areas in black spruce than areas dominated by jack pine (Pinus banksiana) or a mixture of jack pine and spruce with dense undergrowth. Where Spruce Grouse breed in patchy black spruce communities, immigration from neighboring populations or inter-patch movement by local individuals may be required to maintain viable populations.

Journal of Field Ornithology↗
USGS1984

Breeding biology of the blue-gray noddy

Blue-gray Noddies, the smallest marine terns, are similar in many respects to all tropical terns in Hawaii: single-egg clutches are laid, growth and development take about 7 weeks, breeding is colonial. Its small size results in eggs that comprise over 27% of adult body weight, compared to 15-20% for most marine terns (Langham 1983). Blue-gray Noddies are widespread in the tropical Pacific, but populations are generally small. This may be the result of its inshore feeding habits and the fact that it is a resident species (Diamond 1978). However, populations in the Hawaiian Archipelago are probably limited by the availability of suitable nest sites in cliffs or rocky outcrops, not food supplies..... Food habits in Hawaii confirm the unique dependence of this species on sea-striders but consumption may be seasonal Blue-gray Noddies take the smallest prey of any seabird in Hawaii and may feed on a lower trophic level..... The Hawaiian population is apparently heavier and produces larger eggs than Blue-gray Noddies elsewhere in the Pacific. This conforms with the general proposition that Hawaiian seabirds are larger than those in the central Pacific (Harrison et al. 1983). The Hawaiian population also has a more predictable breeding season than those farther south.This may be due to a greater seasonality of food supply, but the factors that control the timing of breeding are not clear. There does not appear to be any competition for nest sites with other seabirds.....Our information on growth and development will enable future investigators to estimate the ages of chicks during brief visits to Blue-gray Noddy colonies. This will facilitate programs that are designed to monitor the basic health of seabird populations and to detect changes from baseline that may result from human activities or oceanographic conditions.

Journal of Field Ornithology↗
USGS1989

Observations of a nest of red-crowned ant-tanagers in Paraguay

The nest and nesting behaviorof a pair of Red-crowned Ant-Tanagers ( Habia rubica rubica) from Paraguay is described. Results are compared with those from studies of other subspecies. Because the species occurs in temperate, subtropical, and tropical habitats from Mexico south to Paraguay, northern Argentina, and southeastern Brazil, we expected details of breeding to differ in different parts of the range. Other than differences in the timing of breeding north and south of the equator, only details of nest structure and egg coloration showed geographic variation.

Journal of Field Ornithology↗
USGS1998

Digital playback and improved trap design enhance capture of migrant Soras and Virginia Rails

We used playback of rail vocalizations and improved trap design to enhance capture of fall migrant Soras ( Porzana carolina ) and Virginia Rails ( Rallus limicola ) in marshes bordering the tidal Patuxent River, Maryland. Custom-fabricated microchip message repeating sound systems provided digitally recorded sound for long-life, high-quality playback. A single sound system accompanied each 30-45 m long drift fence trap line fitted with 1-3 cloverleaf traps. Ramped funnel entrances improved retention of captured rails and deterred raccoon ( Procyon lotor ) predation. Use of playback and improved trap design increased trap success by over an order of magnitude and resulted in capture and banding of 2315 Soras and 276 Virginia Rails during September and October 1993-1997. The Sora captures more than doubled the banding records for the species in North America. This capture success demonstrates the efficacy of banding large numbers of Soras and Virginia Rails on migration and winter concentration areas.

Journal of Field Ornithology↗
USGS1998

Effects of radio transmitters on migrating wood thrushes

We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of Wood Thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores. We used two strengths of line, 5- and 9-kg test-strength braided Dacron, to attach the transmitters using the thigh-harness method. We recaptured 13 returning radio-marked Wood Thrushes, seven of which were still marked. Six of the seven birds marked with the 5-kg test harnesses lost their transmitters within 1 yr while all six of the 9-kg test harnesses were still attached up to 21 mo later. Radio-marking did not reduce the return rates of adults and immatures, and the transmitters did not cause radio-marked birds to lose more mass than banded-only birds. Wood Thrushes can successfully carry a transmitter during migration with no detectable negative effects. We recommend continued use of the thigh-harness method, but we encourage the use of 5-kg cotton line.

Journal of Field Ornithology↗
USGS1998

Increasing point-count duration increases standard error

We examined data from point counts of varying duration in bottomland forests of west Tennessee and the Mississippi Alluvial Valley to determine if counting interval influenced sampling efficiency. Estimates of standard error increased as point count duration increased both for cumulative number of individuals and species in both locations. Although point counts appear to yield data with standard errors proportional to means, a square root transformation of the data may stabilize the variance. Using long (>10 min) point counts may reduce sample size and increase sampling error, both of which diminish statistical power and thereby the ability to detect meaningful changes in avian populations.

Journal of Field Ornithology↗
USGS1998

The North American Bird Banding Program: Into the 21st century

The authors examined the legal, scientific, and philosophical underpinnings of the North American Bird Banding Program [BBP], with emphasis on the U.S. Bird Banding Laboratory [BBL], but also considering the Canadian Bird Banding Office [BBO]. In this report, we review the value of banding data, enumerate and expand on tile principles under which any modern BBP should operate, and from them derive our recommendations. These are cast into a Mission Statement, a Role and Function Statement, and a series of specific recommendations addressing five areas: (1) permitting procedures and practices; (2) operational issues; (3) data management; (4) BBL organization and staffing; and (5) implementation. Our major tenets and recommendations are as follows: banding provides valuable data for numerous scientific, management, and educational purposes, and its benefits far outweigh necessary biological and fiscal costs, especially those incurred by the BBL and BBO; because of the value of banding data for management of avian resources, including both game and nongame birds, government support of the program is fully justified and appropriate; all banding data, if collected to appropriate standards, are potentially valuable; there are many ways to increase the value of banding data such as by endorsing, promoting, and applying competence and/or training standards for permit issuance; promoting bander participation in well-designed projects; and by encouraging the use of banding data for meta-analytical approaches; the BBL should apply, promote, and encourage such standards, participation, and approaches; the BBP should be driven by the needs of users, including scientists and managers; all exchange of data and most communication between banders and the BBL should become electronic in the near future; the computer system at the BBL should be modernized to one designed for a true client-server relationship and storage of data in on-line relational databases; the BBL should continue to maintain high quality control and editing standards and should strive to bring all data in the database up to current standards; however, the BBL should transfer a major portion of the responsibility for editing banding data to the bander by providing software that will permit the bander to edit his/her own data electronically before submission to the BBL; the BBL should build the capacity to store additional data tied to original band records able to be pre-edited and submitted electronically, such as recapture data, appropriate data from auxiliary marking (e.g. resightings of color-marked birds), and other data that gain value when pooled from many banders (e.g., measurements); however, the BBL should only accept such data if they are collected using standardized methods and as part of an established program designed to utilize such data; now is the time to consider options for implementing a Western Hemisphere banding program, with leadership from the BBL; the Patuxent Electronic Data Processing Section should become part of the BBL; additional scientific and technical staff must be added to the BBL; an Implementation Team should be formed to expedite our recommendations, following timetables outlined in this document.

Journal of Field Ornithology↗