The study

Study area

The behavioural study of the blackbuck was commenced on 17-7-1977. The study was conducted at the Guindy Park Reserve Forest (GPRF) with short trips to Point Calimere in the Tanjore District for comparative study. This habitat was chosen as it is in close proximity to the author’s home, an important consideration as it was possible to carry on the normal workaday business and still find time to go to the site often. Also, since this was funded by the author, a far away site would not have made it possible.

This study was undertaken on a part-time basis but after the first year, and on deeper involvement with the subject, it was taken up full time. The major part of this study was carried out at the disused Polo Field at the Guindy Park Reserve Forest, where a large number of blackbuck congregate. The Polo Field is a large meadow of approximately 440 yards × 250 yards, bound on the Northern and Western sides by the Government House buildings and on the east by a well-used track. On the Southern side is a metalled road. The Northern and Western sides are undisturbed. The Polo Field lies within the Guindy Park Reserve Forest, which now measures about 619 acres of forest of the dry deciduous type. Within its confines are the Government House proper, with its ancillary buildings, the Children’s Park, Snake Park, Guru Nanak College, and the Cancer Hospital. These probably take up about 50 acres of the Park. Within this forest are herds of free ranging cheetal or spotted deer Axis axis and blackbuck. These roam all over the Government House grounds though not over the rest of the institutions. The total area of the Government House and forest was around 800 acres.

Studies were also conducted on blackbuck herds in the adjoining Indian Institute of Technology (IIT) campus and also at the Kodikarai Reserve Forest at Point Calimere.

Methods

The methods adopted during the first year of this study were of the ad libitum field notes type. During the second part of the study this was developed into a focal animal sampling using scan technique (Altmann 1974). Observations were made using a Kraus 8 × 40 binoculars from a fixed point. All observations were made during the daylight hours from 6 a.m. to 6 p.m. Some short night observations were also made.

Focal sampling was done on the basis of a 15-minute sampling unit. Apart from field notes and other observation, 520 units of their behaviour were recorded. Identification of individual animals was done by means of studying the horns of males. The number of spirals on the horns, the size and girth, and most important, the angle at the very tips of the horns. The horn tips of blackbuck protrude at various angles. Rarely do both the tips stand straight up. The angle made by the horns was also taken into account. Thus it was possible to have 18 males individually identified. This system, combined with the fact that territorial males are more or less always at their post in their territory, made identification quite reliable throughout the greater part of the study. One drawback of this system of identification was however noticed. The identity of young males with less than 3 or only 3 spirals, to their horns did become a bit uncertain towards the end of the study period. The horns in this age group tend to grow sufficiently in three years to make identification towards the end a bit uncertain, though the older age group did not show any or sufficient growth during the three years to cause any uncertainty.

The animals were not named, but given letters, viz., A, B, C, etc. There was only one physically deformed animal at the GPRF, with a malformed horn. It was considered not advisable to accept cuts or other scratch marks on the body for identification as hair growth soon covered all marks. Positive identification of females was found to be difficult. Short of marking or tagging no other means was feasible. Neither money nor facilities for tagging was available. The records of this study are therefore regrettably biased towards the male of the species.

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