1. Explanations for the integration of migratory and non-migratory (resident) birds in the Neotropics have been complicated by the paradox that arthropod abundances are low when bird abundances reach their annual peak. The breeding currency hypothesis offers an explanation for this paradox by postulating that resident birds are limited in the breeding season by the availability of large arthrop...

In order to characterize the endocrine changes associated with ovarian function and pregnancy in wild redfronted lemurs (Eulemur fulvus rufus), profiles of immunoreactive 5alpha-pregnane-3alpha-ol-20-one (5-P-3OH) and total estrogens (E(t)) in feces were generated during the breeding season and gestation. HPLC data confirmed the presence of high amounts of 5-P-3OH in the feces of redfronted lem...

In order to characterize the endocrine changes associated with ovarian function and pregnancy in wild redfronted lemurs (Eulemur fulvus rufus), profiles of immunoreactive 5α-pregnane-3α-ol-20-one (5-P-3OH) and total estrogens (E t) in feces were generated during the breeding season and gestation. HPLC data confirmed the presence of high amounts of 5-P-3OH in the feces of redfronted lemurs and s...

When prey animals discover a predator close by, they mob it while uttering characteristic sounds that attract other prey individuals to the vicinity. Mobbing causes a predator to vacate its immediate foraging area, which gives an opportunity for prey individuals to continue their interrupted daily activity. Besides the increased benefits, mobbing behaviour also has its costs owing to injuries o...

Marine protected areas (MPAs) are increasingly being used as a conservation tool for highly mobile marine vertebrates and the focus is typically on protecting breeding areas where individuals are aggregated seasonally. Yet movements during the non-breeding season can overlap with threats that may be equally as important to population dynamics. Thus understanding habitat use and movements of spe...

the aim of this study was to evaluate the reproductive efficiency of short and long term treatment with progestagens in addition to pregnant mare serum gonadotropin (pmsg) in arabian ewes during the non-breeding season. a total of 56 ewes were divided into three groups: in group i vaginal sponges (60 mg medroxy progesterone acetate; map) were applied and removed after 6 days; in group ii, vagin...

Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed (Composite III and northwestern whiteface), mating season (August, October, and December), ewe age (1, 2, and 3 yr), and their interactions on reproductive traits of F1 ewes. A total of 1,799 F1 ewes produced 3,849 litters from 4,804 exposures to Suffolk rams during 35-d mating season...

The seasonally determined demographic structure of two semi-arid rodents, both agricultural pest species (the leaf-eared mouse (Phyllotis darwini) in Chile and the multimammate mouse (Mastomys natalensis) in Tanzania), is analysed using capture-mark-recapture (CMR) statistical models and measures for elasticity (the relative change in the growth rate due to a relative unit change in the paramet...

The present study was conducted to determine the effect of seasonal and climatic variations on semen characteristics of Nili-Ravi buffalo breeding bulls in Sahiwal and Bahawalpur districts of Punjab, Pakistan. For this purpose, 14 adult NiliRavi buffalo breeding bulls (n=7 from each of Semen Production Unit (SPU) Qadirabad, Sahiwal and SPU Karaniwala, Bahawalpur), were used. Semen samples were ...

When prey animals discover a predator close by, they mob it while uttering characteristic sounds that attract other prey individuals to the vicinity. Mobbing causes a predator to vacate its immediate foraging area, which gives an opportunity for prey individuals to continue their interrupted daily activity. Besides the increased beneŽ ts, mobbing behaviour also has its costs owing to injuries o...