Staging areas and migratory stopovers of wetland birds can function as geographic bottlenecks; common dependence among migratory wetland bird species on these sites has major implications for wetland conservation. Although 90% of playa wetlands in the Rainwater Basin (RWB) region of Nebraska, USA, have been destroyed, the area still provides essential stopover habitat for up to 10 million waterfowl each spring. Our objectives were to determine local (within wetland and immediate watershed) and landscape-scale factors influencing wetland bird abundance and species richness during spring migration at RWB playas. We surveyed 36-40 playas twice weekly in the RWB and observed approximately 1.6 million individual migratory wetland birds representing 72 species during spring migrations 2002-2004. We tested a priori hypotheses about whether local and landscape variables influenced overall species richness and abundance of geese, dabbling ducks, diving ducks, and shorebirds. Wetland area had a positive influence on goose abundance in all years, whereas percent emergent vegetation and hunting pressure had negative influences. Models predicting dabbling duck abundance differed among years; however, individual wetland area and area of semipermanent wetlands within 10 km of the study wetland consistently had a positive influence on dabbling duck abundance. Percent emergent vegetation also was a positive predictor of dabbling duck abundance in all years, indicating that wetlands with intermediate (50%) vegetation coverage have the greatest dabbling duck abundance. Shorebird abundance was positively influenced by wetland area and number of wetlands within 10 km and negatively influenced by water depth. Wetland area, water depth, and area of wetlands within 10 km were all equally important in models predicting overall species richness. Total species richness was positively influenced by wetland area and negatively influenced by water depth and area of semipermanent wetlands within 10 km. Avian species richness also was greatest in wetlands with intermediate vegetation coverage. Restoring playa hydrology should promote intermediate percent cover of emergent vegetation, which will increase use by dabbling ducks and shorebirds, and decrease snow goose (Chen caerulescens) use of these wetlands. We observed a reduction in dabbling duck abundance on wetlands open to spring snow goose hunting and recommend further investigation of the effects of this conservation order on nontarget species. Our results indicate that wildlife managers at migration stopover areas should conserve wetlands in complexes to meet the continuing and future habitat requirements of migratory birds, especially dabbling ducks, during spring migration.
Fungicide use on row crops is increasing dramatically due to promotion of these products for general plant health and increased yield even during low disease pressure. These fungicides are applied aerially, which may lead to amphibian exposure within fields or in nearby habitat. Exposure to three of these fungicides at environmentally relevant conditions resulted in mortality for Bufo tadpoles and juveniles for two of the fungicides. Headline®, the most commonly used on row crops, resulted in >50% mortality for juveniles at corn label application rates and 100% mortality for tadpoles at one-tenth the label rate for corn. Stratego® killed 40% of exposed tadpoles on average at the corn label rate, but only 7% of the juveniles. Overall, Quilt® appeared less toxic than the other fungicides, resulting in 7 to 10% mortality of tadpoles and 4 to 22% mortality of juveniles at all concentrations (from 0.1× to 10× label rate). These fungicides, especially Headline, may pose a major hazard for amphibians exposed as tadpoles and/or juveniles at environmentally relevant concentrations.
About 50% of farmers/ranchers in the PLJV region had heard of the term "playa" or "playa lake" which translates to about 115,000 individual farmers/ranchers in the PLJV region. Across BCRs, landowner awareness (heard of "playa") ranged from a low of 24% in BCR18CO to a high of 90% in BCR18TX. More revealing was the key question inquiring if respondents had playas on the lands they managed. Playa presence ranged from a low of about 8%-that is, 8% of properties had at least one playa lake-in BCR18CO, BCR19KS, and BCR19OK, to a high of 48% in BCR18TX. These survey data yielded an estimate of playa numbers in the PLJV region within the range of 41,000 to 127,000 playas, which easily encompasses playa numbers promoted by the JV of about 60,000. When asked about certain playa functions, about 50% of landowners did not know whether or not playas recharged groundwater. This indicates there is a need to continue to communicate about the link between playas and recharge of the Ogallala Aquifer. Of 13 possible resources that might warrant additional conservation effort, farmers/ranchers said they supported "more conservation than now" for only one-the Ogallala Aquifer. Their second-ranking conservation concern was the Conservation Reserve Program ("same support as now"). When asked how willing they would be to implement certain conservation practices if given incentive, 28% of all playa landowners were "highly willing" and 46% were "moderately willing" to plant native grass buffers around playas/wetlands, indicating a significant landowner demand for playa conservation programs. A number of different incentives would be well received by landowners to help improve their management of playas and wetlands. Most popular among landowners-those who have playas, those that do not, and those that don't know-would be if "playa/wetland management helped my bottom line." In fact, the most popular incentive for all types of landowners would be some form of iii financial remuneration, augmented by knowledge that their actions were helping the land/water resources. Predictably, landowners in BCRs in which playas were more common were better able to identify playas as a type of wetland. Moreover, landowners who said they actually had playas on their properties were much more knowledgeable about playa lakes than those who did not have playas on their lands. Looking at farmers/ranchers across the PLJV region, those who said they had playas on their lands said playas and wetlands constituted an overall positive feature (68%), while 25% said playa lakes/wetlands were an overall negative feature. A majority of respondents who indicated they did not have playas on their properties still were prone to characterize playas and wetlands as a positive feature (53%), though a large group (39%) said "don't know." For landowners who said they had playas on their properties-and thought playas were an overall positive presence-the highest-ranking benefit was "attracts wildlife." Ranking second was "recharges groundwater," third was "improves groundwater...
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