The Effects of Agricultural Management on Wetland Birds

With the rapid growth of the human population, there is a need to balance biodiversity conservation with achieving food security. Increasing agricultural inputs has greatly augmented food production on smaller areas of land, but generally has negative effects on biodiversity. As natural wetlands decline worldwide, birds are increasingly using flooded agricultural land. The objectives of this thesis are (1) to determine what affects the use of flooded agriculture by waterbirds and (2) to determine what has been studied about the effects of agricultural intensification on wetland birds. I examined the factors affecting the use of flooded agriculture by waterbirds by studying the abundance and species richness of waterbirds on rice fields during the growing season. I modeled bird abundance and species richness as a function of spatiotemporal variables, daily field conditions, and chemical management and compared a set of candidate models using subsets of these variables using an information theoretic approach. Abundance and species richness of waterbirds had a clear relationship with water management, but I found no evidence to suggest that they were influenced by chemical management factors. To determine what has been studied about the effects of agricultural intensification on wetland birds, I created a systematic map to collate the available evidence on this topic. I conducted a systematic review for articles that included information on birds using flooded agriculture of differing levels of agricultural intensification. The systematic map consists of 102 studies that met my inclusion criteria. I found that the vast majority of the studies were conducted in rice fields and flooded wet meadows used for grazing and silage. A wide variety of methods of intensification were studied, but the majority of the studies only examined the effects of intensification on bird abundance. I suggest that more studies are needed on the effects of intensification on bird survival and reproduction in order to determine the true habitat value of flooded agriculture for wetland birds. Overall, the results of this thesis suggest that the intensification of flooded agriculture cannot be universally described as beneficial or detrimental to wetland birds. Understanding the specific mechanisms through which agricultural inputs affect birds will be key in balancing conservation with food production