Throughout the breeding season, changing environmental and biological conditions can lead to variation in the reproductive landscape of many species. In alpine environments temperature is a key driver of behaviour for small ectotherms such as insects, but variable biotic factors such as mate quality and availability can also influence behaviour. Kosicuscola tristis is a small semelparous grassh...

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive s...

This study reports the gender and seasonal specificity of hormonal, behavioral, and coloration responses displayed by "resident" male lizards (Sceloporus undulatus) exposed to male or female "intruders" during staged encounters in outdoor enclosures. Resident males were engaged in staged encounters with males or females for 1 h per day on 9 consecutive days during the breeding and postbreeding ...

Male golden-collared manakins gather on leks and perform an acrobatic display to attract females. In temperate breeding species, testosterone (T) activation of courtship displays has been well studied. Few studies have examined T activation of displays in tropical species; even fewer have explored the activational role of T in elaborate courtship displays such as in the manakin. In some tropica...

In nest-building species predation of nest contents is a main cause of reproductive failure and 16 parents have to trade off reproductive investment against antipredatory behaviours. While this trade-off is modified by lifespan (short-lived species prioritise current reproduction, long-lived 18 species prioritise future reproduction), it may vary within a breeding season, but this idea has only...

Introduction Artificial insemination provides a method to inseminate a large number of females to a single sire selected and proven to be an industry leader for economically relevant traits. Thus, genetic change in a herd can occur quickly through the use of artificial insemination. With natural service, herd bulls are also selected for economically relevant traits but are limited on the number...

Two experiments, one examining oestrus and ovarian activity in 5 genotypes of young ewes exposed continuously to teaser rams and the other examining the onset of the breeding season in 4 separate strains of young Merino ewes, were carried out at Hamilton. In each experiment there were genetic differences in the duration of the non-breeding season. In experiment 1, Merinos and Comebacks had a sh...

With the goal of characterizing the type and degree of injuries and blemishes incurred by horses living under natural social conditions, all members of a semi-feral herd of ponies were inspected on 4 occasions over a period of 28 months. Two occasions were during breeding/foaling season and 2 during non–breeding/foaling season months. On each occasion, each animal was examined (N = 47–65) and a...

Gambel's white-crowned sparrow, Zonotrichia leucophrys gambelii, is a long-distance migrant that, in contrast to other subspecies of white-crowned sparrow, does not form vocal dialects. I studied the process of vocal development in the field and laboratory to determine how it differed from the process in three other subspecies previously studied. Four common song types existed in a random spati...