Crop fields versus wetlands

For purposes of this web-page, the results are presented in a nutshell without statistics or actual data. Maximum mortality at all stages of nesting and growth was related to humans. Egg lifting was severely high in nests of crop field pairs while grass cutters were seen to remove eggs from nests in few areas from nests of wetland pairs. Mortality of chicks less than 15 days of age could not be ascertained definately in most cases. Post-fledging mortality was highest due to collision/ electrocution with supply wires. Studies on post-weaning mortality and dispersion using chicks colour-banded with standard plastic colour bands are currently on.

Overall, wetland pairs had eggs much larger than those of the crop field pairs. This implies a deficiency in nutrition to crop field pairs. Investigations to locate the nutrients that may have become less available or completely unavailable to crop field pairs are currently on. Hatching, fledging and weaning success was uniformly higher in nests and young of crop field pairs. Crop field pairs defended much larger territories as opposed to wetland pairs. This implies that crop field pairs need a larger area to obtain the required food for the adults and chicks to survive, while the same can be obtained in a lesser area when natural wetlands form a substantial part of the territory.

Data from the 2001 season will be used to see if the above trends hold good across years. However, statistically significant conclusions regarding egg size and mortality from the 2000 season amply indicate that crop fields are clearly sub-optimal for Sarus Cranes with respect to breeding biology and possibly nutrition. Studies have been instituted to check for differences in behaviour as well and will be incorporated in the final analysis. With conversion of natural wetlands to crop fields, the 'quality' of Sarus Cranes being added to the population is being reduced. The long-term ill effects of this phenomena are that they could affect Sarus Crane longevity, fecundity and behaviour negatively. Recruitment to the wild population will decrease with a larger number of conversions of natural wetlands to crop fields as the phenomena decreases breeding success. These obviously do not augur well for Sarus Cranes and the necessity to preserve and maintain sacrosanct the remaining large and small marshlands as Sarus habitat cannot be overemphasised.

Reduction of average land holdings of farmers over the years has served to increase apathy of farmers towards the Sarus and egg lifting and chick killing is suspected to rise. With depletion of wetlands, Sarus Cranes will be forced to feed in the crop fields and the likelihood of increased, indeed severe, crop depradation by Sarus flocks and breeding pairs is bound to increase. Both of the above serve to increase the crane-human conflict and may result in the farmers taking steps to permanently remove the crane 'menace' to their fields by poisoning and other methods. Conservation steps, while incorporating preservation of natural habitats, should include involvement of the farming community, education programmes in villages and ideas on farming methods which do not compromise the interests of the farmers or the cranes.