▪ Abstract Intraspecific variation in territory size and shape can have strong effects on population structure and dynamics. The traditional theoretical approach to the study of territory size is based on optimality models that analyze decisions of focal residents as responses to the costs and benefits of defense. These models have stimulated numerous empirical studies showing that territory holders adjust their behavior according to rates of intrusion and availability of food. However, models of optimal territory size are applicable only in limited circumstances because they focus on unilateral decisions rather than on interactions. Furthermore, observational and experimental studies often find that territory sizes are insensitive to food supply. Recently, greater emphasis has been placed on two alternative approaches. The first concerns interactions among contiguous neighbors and how these affect use of space. In these models territory size and shape are determined by the balance of pressure exerted at ...

Approaches to the study of territory size and shape

An energy-time budget model is developed which predicts the influence of various environmental factors upon feeding territory size. For nonbreeding animals maintaining noncontiguous territories, territory size should (1) vary inversely with food production, but directly with competitor density, for feeding-time minimizers (defined here as animals that exhibit relatively fixed daily energy requirements); and (2) vary inversely with both food production and competitor density for food-energy maximizers, animals whose potential reproductive success is positively correlated with their net energetic intake. Concomitant predicted changes in time budgeting provide operational criteria for testing the model. Besides the primary effects of food and competitors, other factors may also influence territory size. Any competitors which successfully invade the territory can decrease the availability of food, forcing both time minimizers and energy maximizers to expand their territories. Where territories are contiguous,...

Food Production and Competitor Density as the Determinants of Feeding Territory Size

This text synthesizes existing knowledge of the process of domestication and how domestication has affected the behaviour of captive wild and domesticated animals, including both farm, zoo and companion animals. Three broad themes are addressed: genetic contributions to the process of domestication; experimental contributions to the process of domestication; the process of feraliztion (i.e. the adaptation of domesticated animals when returned to their natural habitat.

Animal Domestication and Behavior

Domestication effects on aggressive and schooling behavior in fish

The distribution, social behaviour, and feeding behaviour of juvenile Atlantic salmon were studied in a selection of stream and river habitats in northern Scotland using Scuba diving techniques. The results are discussed with respect to food acquisition and choice of feeding site. It is concluded that juvenile salmon feed predominantly on drifting material and that their daytime distribution reflects the current velocity related abundance of drift.

Spatial distribution and feeding in atlantic salmon, Salmo salar L. juveniles

The distribution and density of every species of animal is at least loosely controlled by the distribution and abundance of its food. Particular attention has been paid recently to the distribution of salmonids as affected by selection of the site of the fish's feeding territory (Chapman & Bjornn 1969) and to their numbers as affected by varying abundance of food in different streams (Egglishaw 1967). Evidence that food supply does more than permit or prevent a population of salmonids from inhabiting a stream is as yet equivocal. Mason & Chapman (1965) found that the biomass and numbers ofjuvenile coho salmon (Oncorhynchus kisutch Walbaum) remaining in two stream channels from which they could emigrate were greater in the channel which had a greater food supply. However, since there was no replicate in which the varying rations were switched between channels, the possibility remained that the channel with the greater food supply retained more fish because of a greater number of hiding places, better cover, etc. In comparing two streams, one of which had three times as much food as the other, Egglishaw (1967) found that there were fewer trout in his food-poor stream, but more salmon, so that the total density of salmonids differed little (about 0 45 fish/m2 in the poor compared to 0 55 fish/m2 in the rich stream). Biomass differed even less. The streams were different in other respects besides food, however, which, in this case, may have masked the effect of food supply on density. Le Cren (1965) suggests that while a population of fish may be limited by food in the long run, in some instances other regulatory mechanisms usually reduce the importance of food supply as a regulatory factor. Effects offood supply on behaviour, in contrast to those on population density, have been reasonably well defined. In laboratory experiments with young salmon (Salmo salar L.), provision of food in two daily feedings was followed shortly afterwards by an increase in aggression which subsided gradually 30 min later (Keenleyside & Yamamoto 1962). Symons (1968) found when aggression was measured after immediate effects of feeding had waned, that fish deprived of food for 18-66 h were more aggressive than those receiving an abundance of food. Together these results indicate that, in those natural habitats having a continuous abundant supply of food, young salmon are probably less aggressive than in habitats where they are constantly hungry and meals are sporadic. Chapman (1962) has postulated that aggression of some territorial fish may cause the emigration of others with inferior fighting ability. Presumably an increase in aggression would speed this emigration process. Symons (1968) also suggested that the increase in aggression associated with food-deprivation might, in a natural environment, result in an

P. E. K. Symons

Papers

Behavioural Adjustment of Population Density to Available Food by Juvenile Atlantic Salmon