Breeding success in croplands
Understanding limits to Sarus Crane and Black-necked Stork productivity
Many long-lived waterbird species living on agricultural landscapes now face changing rainfall patterns and altering land use. We tracked multiple pairs of two species of global conservation concern over eight years to understand how they cope with these changes.
Farmlands as breeding habitat
Not conventionally thought to be anything but "human use areas", some landscapes dominated by crops and villages can be habitat for wild species. In Uttar Pradesh, the areas with monsoonal rice and winter wheat crops have surprisingly high densities of breeding waterbirds. In Etawah and Mainpuri districts of Uttar Pradesh, we discovered that Sarus Cranes and Black-necked Storks here maintain year-round territories. Both species live for over 50 years, and appear to have permanent pair-bonds, meaning that once they find partners and breeding territories, these birds live together until both or one of them dies. This is therefore an excellent system to study aspects such as breeding success - a critical component of populations especially of species that are declining on a global scale. To make life easier, we also discovered that individual territories are fairly small for the Sarus (not exceeding 50 ha), and manageable for the Black-necked Stork (3-5 square kilometers). We could track breeding success for each pair each year by visiting territories in late winter when most of the young birds have fledged. We could also closely assess the quality of each territory, how much wetlands each had, and also what changes occurred each year in every single territory. Finally, we measured rainfall on a monthly basis to be able to relate to breeding success of the population, and tracked the breeding success for eight years between 1999 to 2010.
Chicks, chicks and yet more chicks!
Both species were very successful in raising chicks, particularly in years of above-normal rainfall. Estimates of success exceeded that recorded for similar species in other parts of the world, even in managed and protected wetland reserves. Sarus Cranes had record-breaking numbers of pairs raising two chicks each. And Black-necked Storks were recorded, for the first time, to raise four chicks in a single brood, and one brood had a world record of five chicks! The rice-wheat combination of crops, combined with the habits of villages and farmers retaining wetlands of various sizes on the landscape was proving to be an ideal breeding place for these two species despite the changing rainfall patterns.
Land use change and the future
Over the course of the study, we also observed villages expanding, eating into the territories of the cranes and storks. Several crane pairs were permanently removed from the landscape. Farmers also actively converted wetlands to crops reducing the quality of the territory for these species that are wetland dependent.
Our analyses indicated that, for the long-term future, these changes in land use were far more important and detrimental relative to the changing rainfall patterns for both species. We continue to monitor the 250+ Sarus pairs, and the 35+ Black-necked Stork pairs to this day, and undoubtedly, more stories will be told of their lives
Meanwhile, our study helps underscore the importance of traditional practices like maintaining wetlands amid crop fields by panchayats, and by individual farmers. Also, their ability to tolerate large birds like the Sarus and the storks walking around their fields is a key element in the coexistence we were observing. Clearly, these traditional and individual attitudes require to be encouraged and strengthened. The question of long-term persistence of this magical multifunctional landscape, however, remains open. It remains to be seen if these people will choose factories, modern cities, and related forms of development over their current lifestyles. For now, farmers still await the monsoons, and the cranes still walk the fields amid the long stalks of mustard and wheat in the winter.
- Journal Article2011Agricultural intensification, rainfall patterns, and large waterbird breeding success in the extensively cultivated landscape of Uttar Pradesh, IndiaBiological Conservation 144: 3055-3063. doi:10.1016/j.biocon.2011.09.012
In countries with high human populations, using agricultural areas as multifunctional systems to produce food for humans and retain wildlife may be an efficient conservation strategy for many species. Inclusion of natural habitat and species requirements on agricultural landscapes explicitly into planning processes are precluded by lack of information on drivers of species persistence. Climate change is an additional emerging complexity, and adaptation plans for agricultural landscapes are biased towards intensification to secure long-range food production. I examine the conservation potential of an agricultural landscape in two districts of Uttar Pradesh, north India where agricultural intensification and altered rainfall patterns are predicted to occur. I assess stressors affecting breeding success over eight years of two large waterbirds of conservation concern – Sarus Cranes and Black-necked Storks. Both species had high breeding success that improved with total rainfall and more wetlands in breeding territories. Agricultural and township expansions deteriorated territory quality and reduced breeding success. Sarus Crane populations were predicted to decline relatively rapidly if development activities continued to displace breeding pairs. Black-necked Storks appeared resilient over the long-term notwithstanding reduced breeding success in low-rainfall years. Waterbird nesting habitats (wetlands and trees) were retained in Uttar Pradesh as community lands by villages and by state government via legal provisions suggesting the utility of multiple conservation approaches. Incorporating species requirements explicitly, alongside traditional land use practices conducive for habitat conservation, into adaptation planning and conservation policy will be necessary to retain long-term multifunctionality of such agricultural landscapes.