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At least 613 records · Page 34Linked to original sources
USGS2006

Age-related body mass and reproductive measurements of gray wolves in Minnesota

Based on 65 free-ranging gray wolves (Canis lupus) of known age and 25 of estimated age examined during summers of 1970-2004 in northeastern Minnesota, body mass of both males and females peaked at 5 or 6 years of age, with mean masses of 40.8 kg and 31.2 kg, respectively. Testis size varied as a function of age and month through at least 8 years of age, with length plus width ranging from 1.9 to 7.8 cm. Most females aged 4-9 years bred based on assessment of nipple sizes; those that had not bred had average lower body mass than those that had. This is the 1st report of such data from known-aged wolves.

Journal of Mammalogy↗
USGS1990

Homing and reproductive habits of mallards, gadwalls, and blue-winged teal

We studied mallard ( Anas platyrhynchos ), gadwall ( A. strepera ), and blue-winged teal ( A. discors ) populations on 2 study areas of 22.6-km 2 each in central North Dakota during 1976-81. Data regarding rates of return of females to natal or previously used nesting areas, nest site selection, and productivity of hens of different ages were collected from 1,166 nasal-marked and 2,142 banded hens of the 3 species and from 740 web-tagged mallard and gadwall young. In spring, yearling mallard and gadwall hens arrived at the breeding site later than older hens. Yearling gadwall hens initiated nesting about 1 week later than 2-year-old hens, and 2-year-old hens began nesting about 1 week later than hens older than 2 years. Gadwall hens older than 2 years also had a longer nesting season. Mallard and gadwall nest densities were highest in those cover types with the highest visual obstruction ratings. Cover preference in descending order of use was seeded nesting cover, odd areas, roadside, dry wetland, and canal-side. Blue-winged teal nest densities were highest in dry wetland and roadside. Nesting success was different among years, but not among cover types. There was no population increase at any cover type due to homing hens. Overall nesting success was 11, 10, and 23% for mallards, gadwalls, and blue-winged teal, respectively. Recruitment of fledged young was similar for yearling and adult mallard females. Production from yearling gadwall hens was a meager 0.2 young fledged/female. Clutch size was not different between yearling and adult mallard and blue-winged teal hens, but clutch size for all 3 species declined as the nesting season advanced. More ≥1-year-mallard hens and ≥2-year-old gadwall hens that nested successfully 1 year returned to the study areas the following year than did unsuccessful hens. Gadwall hen return rates also increased with age. Blue-winged teal hen return rates averaged 4% and were not related to hen success or hen age. Mallard and gadwall hens that nested successfully 1 year used the same cover type the next year. Successful returning mallard hens also nested closer to the previous nest site than unsuccessful hens. Twenty-nine percent of hatching year (HY) mallard females returned to the study area, and all of these returned as yearlings (second summer). Nine percent of HY gadwalls returned, approximately half as yearlings and the remainder as 2 year olds. Duckling survival from hatching until near fledging was 0.681 for mallards and 0.828 for gadwalls. An overall direct band recovery rate of 8% for HY mallard hens was not different than that of older hens. Gadwall direct band recovery rates decreased through the HY (11%), yearling (5%), and >2-year (1%) age classes.

North Dakota↗
USGS1993

Puerto Rican parrot (Amazona vittata) reproductive behavior: a guideline for management of active nests

One explanation for the failure of intensively monitored Puerto Rican Parrot nests is that observers may lack the information needed to evaluate pair behavior and to recognize behaviors indicative of nest problems. I examined the behavior of Puerto Rican Parrots during eight non-problematic and six problematic nesting attempts to 1) describe behavior of pairs that experienced no notable nest problems and 2) to identify and describe behaviors associated with nest problems. I examined nest attendance, duration of attentive periods, and frequency of nest visits for both males and females, and duration of periods away from the nest for females only. Adult behavior during incubation and early chick rearing at non-problematic nests was well-defined. Females spent an average of 93.2 to 97.3% of the observation period in their nests during incubation and generally left their nests for average periods of 5 to 12 min. Female nest attendance generally declined and recesses became longer as chick rearing progressed. Males rarely entered their nests during incubation, but they generally established a regular pattern of nest visits within seven to 10 days of hatching of their young. In some cases, incidents of human disturbance to nest pairs during incubation and early chick rearing were associated with sudden changes in behavior. The key indicator of nest problems (abandonment during incubation or loss of young) was unexpected declines in female nest attendance. Declines were often accompanied by unexpected increases in female recesses or frequency of female nest visits, and sometimes by increases in male nest visits. Abandonment of nests during incubation was associated with repeated incidents of potentially disturbing activities (e.g., nest inspections). Deaths of embryos and young were associated with behaviors that allowed increased cooling of embryos.

Book↗
USGS1977

Reproductive maturation and breeding of woodcock in North Carolina

Breeding woodcock (PhiJohela minor) were studied in North Carolina during the winters and springs of 1974-75 and 1975-76.. Measurements of testes and ovaries from 19 male and 30 female woodcock suggest that gonadal recrudescence in many woodcock occurs on the wintering grounds. In males, testicular recrudescence occurred as early as December and was accompanied by territory selection and courtship activity. Of 15 females collected in February, 5 had shelled eggs in the oviduct. Seven woodcock broods, located from 1 March to 30 April, were banded, aged, and released. From estimated clutch completion dates it appears that broods were successfully hatched from clutches completed as early as 21 January. Because of the early nesting of woodcock in North Carolina, hunters and land managers need to be aware of woodcock breeding habits and their need for protection during late winter.

Book chapter↗