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At least 1,045 records · Page 58Linked to original sources
USGS1981

Breeding habit of the toad Bufo coccifer in Costa Rica, with a description of the tadpole

The breeding habits of Bufo coccifer were studied in northwestern Costa Rica between 1971 and 1974. This species breeds during the rainy season, at least from May through August. Males chorus from areas of shallow water. Their calls resemble those of Mexican representatives of the species in pulse rate and duration, but are closer to those of other Costa Rican and Panamanian populations in dominant frequency. Thus, our data do not clearly support recognition of Bufo cycladen as a distinct species for the Mexican populations. Amplexus is axillary, and two strings of eggs are extruded simultaneously during oviposition. Tadpoles, described for the first time in this paper, are secretive and do not aggregate. Development to metamorphosis requires about 5 weeks.

Southwestern Naturalist↗
USGS1997

Migration chronology and distribution of redheads on the lower Laguna Madre, Texas

An estimated 80% of redheads (Aythya americana) winter on the Laguna Madre of southern Texas and Mexico. Because there have been profound changes in the Laguna Madre over the past three decades and the area is facing increasing industrial and recreational development, we studied the winter distribution and habitat requirements of redheads during two winters (1987-1988 and 1988-1989) on the Lower Laguna Madre, Texas to provide information that could be used to understand, identify, and protect wintering redhead habitat. Redheads began arriving on the Lower Laguna Madre during early October in 1987 and 1988, and continued to arrive through November. Redhead migration was closely associated with passing weather fronts. Redheads arrived on the day a front arrived and during the following two days; no migrants were observed arriving the day before a weather front arrived. Flock size of arriving redheads was 26.4 ± 0.6 birds and did not differ among days or by time of day (morning midday, or afternoon). Number of flocks arriving per 0.5 h interval (arrival rate) was greater during afternoon (21.7 ± 0.6) than during morning (4.3 ± 1.2) or midday (1.5 ± 0.4) on the day of frontal passage and during the first day after frontal passage. Upon arrival, redhead flocks congregated in the central portion of the Lower Laguna Madre. They continued to use the central portion throughout the winter, but gradually spread to the northern and southern ends of the lagoon. Seventy-one percent of the area used by flocks was vegetated with shoalgrass (Halodule wrightii) although shoalgrass covered only 32% of the lagoon. Flock movements seemed to be related to tide level; redheads moved to remain in water 12-30 cm deep. These data can be used by the environmental community to identify and protect this unique and indispensable habitat for wintering redheads.

Texas↗
USGS1996

Denning behaviour of non-gravid wolves, Canis lupus

Wild wolves (Canis lupus) that had produced pups in earlier years but were not currently pregnant, and ovariectomized captive wolves, dug dens during and after the whelping season even though they produced no pups. These observations suggest that den digging is not a function of pregnancy or of ovarian estrogen or progesterone. We hypothesize that increasing prolactin in spring elicits or mediates den-digging behavior.

Canadian Field-Naturalist↗
USGS1985

Sperm whales (Physeter catodon) in the Gulf of Mexico

The distribution of the sperm whale, Physeter catodon, was documented in the Gulf of Mexico during 1979 to 1981 using regular aerial surveys and opportunistic sightings from ships. Most sightings were in the western Gulf of Mexico in deep waters near the edge of the continental shelf. A total of 47 adults and 12 young animals was sighted in groups containing from one to 14 animals.

Southwestern Naturalist↗
USGS1989

Growth and fatbody cycles in feral populations of the African clawed frog, Xenopus laevis (Pipidae), in California with comments on reproduction

Feral populations of the African clawed frog (Xenopus laevis) exist in several areas of southern California. By following the first cohort of progeny produced by African clawed frogs at a recently colonized site, data on the growth rates and age at first maturity were obtained in field conditions. Females reached maturity at an earlier age than males, grew faster than males, and attained body lengths up to 25% larger than males. Larger females were capable of producing larger numbers of eggs than small females and, therefore, had greater reproductive potential. The relatively stable ambient temperatures of southern California contributed to the possibility of reproduction of clawed frogs during all but the coolest periods of the year. Cycles detected in the mass of fatbodies suggested that nutrients were mobilized from fat prior to and during ovulation. The amount of fat in females varied widely, but fat in males tended to accumulate as the males grew during the study period.

Southwestern Naturalist↗
USGS1998

Predaceous diving beetles in Maine: Faunal list and keys to subfamilies

Records of predaceous diving beetles (Coleoptera: Dytiscidae) collected in Maine are summarized. These records are augmented by field surveys of beetles in Aroostook Co., Maine during 1993-95. Keys to subfamilies are presented with color plates for selected species. A list of diving beetles that have been collected near Maine (state or province) is presented so that investigators will know what additional species might be expected in Maine. Basic taxonomy is presented to facilitate use of keys.

Northeastern Naturalist↗
USGS1997

An example of endurance in an old wolf, Canis lupus

An 11 to 13-year-old Arctic Wolf (Canis lupus arctos) was observed chasing a young Arctic Hare (Lepus arcticus) for 6 to 7 minutes and catching it. This provides an example of the degree of endurance of which an old wolf is capable.

Canadian Field-Naturalist↗
USGS1995

Summer movements and behavior of an Arctic wolf, Canis lupus, pack without pups

A pupless arctic Wolf pack (two adults, three yearlings) studied 5-30 July 1993 on Ellesmere Island, Northwest Territories, traveled nomadically around an area >381 km2 but the alpha pair sometimes left the yearlings at a rendezvous site. All pack members hunted Arctic hares. The alpha pair sometimes fed the yearlings, the alpha male doing so more than the alpha female.

Canadian Field-Naturalist↗
USGS1999

Availability of nest cavity trees for wood ducks (Aix sponsa) at Sunkhaze Meadows National Wildlife Refuge, Maine

The availability of natural cavities for cavitynesting waterfowl, especially wood ducks (Aix sponsa), was unknown ferating forest of Sunkhaze Meadows National Wildlife Refuge, ME. An assessment of cavity availability was needed to determine if the existing nesting box program should be increased. During November to March, 199697 and 199798, I sampled 56 onehalf ha random plots, stratified into 5 types (upland hardwood, upland conifer, upland mixwood, wetland conifer, and wetland hardwood) to assess availability of trees with cavities. The predominant tree species with cavities were red maple (Acer rubrum; 39%) and aspen (Populus sp.; 31%); 72% of all trees with cavities were alive. Density ees/plot averaged from 1.0 +0.4 (x +SE) in wetland softwoods to 1.9 +0.4 in upland hardwoods. This low density of potential cavity trees and the small mean dbh (39.4 +1.6 cm) indicate a young forest with few suitable cavities. Forested areas, especially hardwoods near canopy openings, need to be allowed to mature to increase the number and quality of future cavities. An expanded nest box program seems justified.

Northeastern Naturalist↗