Species richness and distributions of boreal waterbird broods in relation to nesting and brood‐rearing habitats

• Published in: The Journal of Wildlife Management
• Main Authors: Lewis, Tyler L., Lindberg, Mark S., Schmutz, Joel A., Bertram, Mark R., Dubour, Adam J.
• Other Authors: U.S. Geological Survey, U.S. Fish and Wildlife Service
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Melanitta fusca
• Online Access: http://dx.doi.org/10.1002/jwmg.837; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjwmg.837; https://onlinelibrary.wiley.com/doi/full/10.1002/jwmg.837

ABSTRACT Identification of ecological factors that drive animal distributions allows us to understand why distributions vary temporally and spatially, and to develop models to predict future changes to populations–vital tools for effective wildlife management and conservation. For waterbird broods in the boreal forest, distributions are likely driven by factors affecting quality of nesting and brood‐rearing habitats, and the influence of these factors may extend beyond singles species, affecting the entire waterbird community. We used occupancy models to assess factors influencing species richness of waterbird broods on 72 boreal lakes, along with brood distributions of 3 species of conservation concern: lesser scaup ( Aythya affinis ), white‐winged scoters ( Melanitta fusca ), and horned grebe ( Podiceps auritus ). Factors examined included abundance of invertebrate foods (Amphipoda, Diptera, Gastropoda, Hemiptera, Odonata), physical lake attributes (lake area, emergent vegetation), water chemistry (nitrogen, phosphorus, chlorophyll a concentrations), and nesting habitats (water edge, non‐forest cover). Of the 5 invertebrates, only amphipod density was related to richness and occupancy, consistently having a large and positive relationship. Despite this importance to waterbirds, amphipods were the most patchily distributed invertebrate, with 17% of the study lakes containing 70% of collected amphipods. Lake area was the only other covariate that strongly and positively influenced species richness and occupancy of scaup, scoters, and grebes. All 3 water chemistry covariates, which provided alternative measures of lake productivity, were positively related to species richness but had little effect on scaup, scoter, and grebe occupancy. Conversely, emergent vegetation was negatively related to richness, reflecting avoidance of overgrown lakes by broods. Finally, nesting habitats had no influence on richness and occupancy, indicating that, at a broad spatial scale, brood distributions are largely driven by the ...