PROCEEDINGS OF THE ASSOCIATION FOR THE STUDY OF ANIMAL BEHAVIOUR 609

THE BEHAVIOUR OF CATTLE AT PASTURE. By D. T. CHAMBERS, The Grassland Research Institute, Hurley.

The behaviour of the grazing animal has a great influence on the efficiency with which grass is converted into human food. Rejection of herbage growing in the vicinity of faeces means that the area of pasture available must be increased if food intake is not to decline. Preference for some herbage species may be important when cattle can make a choice but it may not affect intake when only one species is available. The habit of selecting the upper parts of plants leads to a build-up of dead material in the base of the sward and, consequently, to a reduced intake of nutrients.

Selection is influenced by the availability and

variability of pasture but, even under heavy grazing pressure, it may not be eliminated. The effects on selection of restricting grazing time and of rearing animals from an early age at pasture are not known.

The highly selective grazing habits of cattle pose difficult problems in grassland management where the aim is to achieve good animal per- formance and utilisation of grass. Wastage of up to 30 per cent. of the crop cannot be toler- ated ; and it may become necessary to deprive the animal of freedom to select its diet. One way of doing this would be to feed mechanically harvested herbage.

ATTRACTING WILD RABBITS TO BAIT-A PRELIMINARY INVESTIGATION IN BRITAIN. By A. J. B. RUDGE, M.A.F.F. Infestation Control Laboratory, Guildford.

Trials in the field, and in the laboratory, have shown that wild rabbits in Britain can be attracted to, and will eat, unpoisoned bait. It is essential for the bait to be laid so as to provide visual continuity between the individual baiting points and the most suitable arrangement is to lay bait in heaps at intervals of two yards or so to form a broken line of bait.

Of six different baits tested whole carrots were found to be most acceptable to rabbits.

Tests on rabbits in cages and in outdoor grass enclosures, showed that carrots were taken even when alternative food was plentiful. Thirteen rabbits confined in a 215 acre enclosure, where a limited quantity of natural food was available, consumed an average of 447 g. of carrots per kg. of body weight per day for 10 days.

Carrot bait was used in twenty-one field trials and the bait was always taken by rabbits. Feeding on bait usually began either on the day it was first laid or after an interval of 1 to 3 days and there was an average of 7 days before a max- imum consumption was reached.

The success of baiting was assessed by exam- ining the contents of stomachs and intestines of sample rabbits. A high proportion of rabbits which could have fed on bait were found to have done so and twenty-nine animals shot or netted at the line of bait had all eaten carrot. Juvenile rabbits were found not to have eaten bait if they were obtained more than 40 yards from the bait line, whereas adult rabbits with carrot in their stomachs were obtained up to 400 yards from the nearest bait.

HYPERPHAGIA, APHAGIA AND FINICKINESS, By P. R. WIEPKEMA, Zoological Laboratory of the University of Groningen, (Haren) the Netherlands.

Lesions in the ventromedian nucleus of the hypothalamus (mice, rats) produce hyper- phagia followed by obesity. It has been found that following such lesions and when the food is unpalatable (e.g. bitter) the animals eat less than normal controls. (Kennedy, Miller, et al., Teitelbaum). These findings are summarized frequently in the paradoxical phrase: De- creased hunger, but increased food intake. Recently Graff and Stellar reported that the neural substrates underlying hyperphagia and finickiness may be different. There was no strict correlation between obesity and finickiness.

A hypothesis is presented here which describes hyperphagia and finickiness (as far as taste is concerned) as a result of lesioning one and the same system.

We know that normal animals can regulate their energy balance over a wide range of tastes of the food. If, however, the taste is very attrac- tive or very aversive, either hyperphagia or aphagia may occur. In these extreme taste regions the normal animal is finicky. Following severe lesions in the ventromedian hypothalamus this compensatory system may be destroyed in such a way that the range over which taste can

610 ANIMAL BEHAVIOUR, XI, 4

be compensated is strongly narrowed. Normal laboratory food, having an optimal com- position, will be now outside the “compensa- tory” range and will represent very attractive food. The animal starts over-eating. If tested for e.g. bitter food the animal will now show to be finicky. Following partial lesions, normal food may be within the “compensatory” range and the animal will remain at a constant and normal weight. However, if tested for finickiness (bitter or sweet food) it may prove to be finicky. Regarding the taste of the food, hyperphagia and aphagia (hypophagia) may be considered as two aspects of the same central concept, finicki- ness.

This hypothesis does not explain why the lesioned animals do not show finickiness during the dynamic phase. To do so a model is repre- sented that is based (1) on a detailed analysis of feeding patterns in mice and (2) on the present knowledge about the physiology of feeding.

In this model the food qualities perceived activate a hunger system, which in its turn stimulates a motoric eating centre. Eating follows and food enters the animal. Three negative feed back channels are distinguished, (1) a stomach factor, (2) a blood glucose factor,

(3) a body fat factor. These three factors sum up in a satiety system, which may inhibit the hunger system.

Ventromedian lesions are likely to destroy gluco-receptors, which leads to a strongly de- creased negative feedback level. During the dynamic phase this may mask finickiness for the most part. After some time the high body fat factor may compensate for the decreased blood- glucose factor and food intake will return to normal. In this static phase finickiness is most marked.

It may be that (1) the compensatory system and (2) the glucoreceptors correlate with two different neural substrates in the ventromedian nucleus of the hypothalamus.

REFERENCES Graff, H. & Stellar, E. (1962). Hyperphagia, obesity and

finickiness. J. camp. physiol. Psychol., 55,418-424. Kennedy, G. C. (1950). The hypothalamic control of food

intake in rats. Proc. roy. Sot. Ser. B., 137,535~548. Miller, N. E., Bailey, C. J. & Stevenson, J. A. F. (1950).

Decreased “hunger” but increased food intake resulting from hypothalamic lesions. Science, 1112, 256-259.

Teitelbaum, P. (1?55). Sensory control of hypothalam& z6e.Ir$aga. J. camp. physiol. Psychol., .

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THE ETHOLOGY OF FOOD HOARDING IN MAMMALS. By M LYALL-WATSON, The Zoological Society of London.

This paper represents an attempt to bring ethological techniques to bear on an aspect of animal behaviour which has hitherto been the preserve of ecological and psychological in- vestigators. It is felt that experimental design in the past has been too narrow, that insufficient emphasis has been placed on the total course of food-hoarding behaviour and that the survival value and evolutionary significance of the hoard to the animal concerned have been unjustifiably neglected.

A comprehensive survey of the different methods employed by mammals in accumulating stores of food is undertaken. Within this survey, a distinction is made between the familiar larder-hoarding of ground-living myomorph and sciuromorph rodents in which food is amassed in one special area, and scatter-

hoarding in which food stores are spread over a wide area. Evidence is presented to show how these different types of hoarding are related to the seasonal requirements of the animal and to the trpe of food being stored.

Because of the unusual nature of scatter- hoarding and the dearth of information con- cerning it, a special study of this behaviour as shown by the South American hystricomorph rodent-the Green acouchi, Myoprocta pratti- is reported on. Details of the sign stimuli of food objects eliciting scatter-hoarding, the factors governing the animals choice of a hoard- ing site and the conditions necessary for later recovery of the hoard, are given. In conclusion, the survival value of scatter-hoarding to the acouchi in the wild and the evolutionary rela- tionship of larder and scatter-hoarding are dis- cussed.