Chicks behavioural response to external Stimuli

Devon Maxwell Anderson 17586704 BScAgric, Animal Production Systems and Aquculture, Stellenbosch, South Africa

Abstract
As animals age they develop ways to best handle situations they encounter. The experiment was divided into two parts. For both parts we investigated the behavioural reactions of 1-2 day old chicks to external stimuli. Part 1 we noted any physical responses to the stimuli whereas in part 2 we noted the chick’s average cheeps per minute when encountering the stimuli. When examining the final results of the experiment it is plain enough to see the effects of the stimuli on the chicks. For part 1 there was only an average of 1 chick showing any form of response to the stimuli of the same size and colour whereas the stimuli that received the most behavioural reaction was that of the sight of another chick with an average of 2.7. For part 2 the highest value recorded was when the chick was left alone without any stimuli, with an average of 77.4 cheeps per minute. The lowest response was when a second chick was used as a stimulus with an average of 32.4 cheeps per minute being recorded. Looking at these results it is easy to interpret that the chicks are less distressed by the presence of other chicks and seek comfort and security in groups.

Introduction
Naturally all living things adapt to best suite their environment. Evolution is loosely defined as the selection of animals with an increased fitness or possession of traits essential for survival through subsequent generations. Traits that contribute to the survival in the natural environment may include different strategies of behaviour (Marx et al., 2001). Animals will obviously have different reactions to different situations they encounter. In this experiment this selection is only made after the chick has considered the possible benefits and consequences of its actions (Marx et al., 2001) Animals function primarily by responding to various types of stimulus through exposure to their external environment. The central nervous system is continually receiving information which is received by the sensory neurons (Stuart, G., Spruston, N., Sakmann, B & Häusser. M. 1997:125). Once the chicks were separated and placed in an unfamiliar environment it was immediately noticeable that they became more distressed. Although that could be an experiment in itself, the purpose of this experiment is to test whether familiar stimuli could affect the behaviour of the chicks in a way that it shows they look for familiarities in an unfamiliar situation.

Method and materials
This experiment was divided into two parts: Part 1: We investigated the reaction of the chicks to each other or objects resembling other chicks. Materials needed to complete this task include; 5 Chicks (1-2 days old), a stop watch, a sheet of paper, yellow cardboard squares, a yellow tennis ball and a mirror. In this task, 5 chicks were used and each chick was tested individually and were exposed to the stimuli for 30 seconds at a time. The chick was placed on a table, 20cm away from the stimulus. If its behaviour was adequate enough, its reaction was noted. There were five different stimuli used to cause a behavioural response. The yellow tennis ball tested the behaviour of the chick when exposed to an object of similar size. The cardboard square tested whether the chick would react to an object of similar colour. A mirror was used to observe the behaviour of the chick when confronted with its reflection. To test the chick’s response to the sound of another chick, a sheet of paper was placed between two chicks and the physical behaviour was observed. Finally two chicks were placed 20cm apart and the behaviour with reference to each other was noted. The hypothesis was that this stimulus would have the greatest number of behavioural response. This task had a function focused on measuring physical behavioural responses. The data would be expressed ranging from 1 to 5 chicks, expressing the average results of 17 experiments measuring the responses of chicks toward stimuli. Part 2: For this experiment we investigated the effects of various stimuli on the cheep rates of the chicks in the unfamiliar environment. Materials needed to complete this task include; 5 Chicks (1-2 days old), a stop watch, 2 cardboard boxes, a bench lamp and a mirror. Our method for this task was fixated around measuring the verbal distress of a chick, expressed as cheeps, within a minute’s exposure to a stimulus. The 5 chicks were kept in one cardboard box, while the other box was used to carry out the experiment. Each chick was placed inside the box (alone), along with a specific stimulus for duration of one minute. The distress of the chick was recorded by counting the number of cheeps within that minute. Each chick was placed in a different unfamiliar environment with a given stimulus. Initially the distress was measured with the chick placed in the box alone. The desk lamp was used to measure the chicks response to a difference in temperature and of course light intensity. As in a previous part, the chick was confronted with its reflection using a mirror however in this experiment the verbal distress was measured. Finally another chick was placed in the box to observe whether the chick would experience less stress.

Results
3 2,5 2 1,5 1 0,5 0 Colour Same size Sound Sight(mirror) Another chick

Average chick response (out of 5)

Figure 1: Column graph representing the number behavioural responses by chicks when exposed to specific stimuli.

Another Chick

Mirror Average cheep response Light exposure

Alone

0

20

40

60

80

100

Figure 2: Bar graph representing the average cheep rates with response to specific stimuli per minute.

Discussion
Both experiments seem to have given us clear results in terms of different responses to different stimuli. In part 1 we identified that there was a greater response to stimuli that are familiar to the chicks. When the chicks were only separated by the sheet of paper it was noted that in some cases the chicks moved closer together. Research has shown that chicks are very sensitive to sound and proves to be the primary form of communication in their vulnerable stage of life (Marx et al., 2001). The mirror reflection of the chick also gave us a large response, this would most likely be due to the fact that the chick recognized its reflection as another chick. The biggest contributor to the fact that our results were not very clear is most likely because the chick was placed in an unfamiliar environment and its natural defence mechanism at a young age would be to be still and keep quiet. The highest response to stimuli for part 1 was the response from that of another chick in the environment. . At this young age these chicks are very vulnerable and tend to move in groups as a source of safety and security as well as heat (Sluckin et al., 1979). It is evident in Figure 1 that there is a significant increase in behaviour when exposed to stimuli directly relating to physical and verbal characteristics of other chicks. (Figure 1 standard deviation=0.63) In Part 2 we measured the chicks distress levels by their number of cheeps per minute. In Figure 2 (average cheep rate after exposure to stimuli) we notice that the lowest cheep rate average is for when it was exposed to another chick. A possible explanation for this could be, as previously mentioned, very young chicks tend to move in groups as a sense of security (Sluckin et al., 1979). By looking at Figure 2 we notice that there is a higher cheep rate average for when the chick was exposed to a reflection of itself compared to when a light source is shone on it. This could be due to the fact that the chick became confused and more distressed when confronted by a reflection of itself and possibly also due to the fact that the lab was at a low temperature and the chick was looking for a familiar source of comfort and security. As expected the highest average cheep rate came from when the chick was alone in the environment, isolated from all external stimuli. The chick relies on its vocalization to communicate in times of distress, as previously mentioned, (Marx et al., 2001).

References
Marx, G., Leppelt, J & Ellendorff, F (2001) Vocalization in chicks (Gallus gallus gom.) during stepwise social isolation. Applied Animal Behaviour Science. Stuart, G., Spruston, N., Sakmann, B & Häusser. M (1997) Action potential initiation and backpropagation in neurons of the mammalian CNS. Trends in Neurosciences. Sluckin, W., Berryman, J.C., Mayes, A & Mann, D (1979) Chicks' responses to familiar stimuli in unfamiliar environments. Quarterly Journal of Experimental Psychology.