Relative Foraging Value to Lesser Scaup Ducks of Native and Exotic Clams from San Francisco Bay

Invasions of exotic invertebrates have greatly altered many aquatic communities, but impacts on the foraging energetics of predators seldom have been assessed. In San Francisco Bay, California (USA), a major community change occurred with introduction of the Asian clam (Potamocorbula amurensis) in 1986. This species now greatly outnumbers the previous clam prey of a variety of sharks, rays, sturgeon, flatfish, and crabs, as well as several diving duck species for which the bay is the most important wintering area on the U.S. Pacific Coast. P. amurensis also accumulates much higher levels of some contaminants than the formerly dominant prey. Because alteration of the food base or contaminated foods on wintering areas may be factors in the population decline of scaup ducks, effects of this exotic invasion are important to assess. For Lesser Scaup (Aythya affinis), we studied effects of differences in nutrient content, digestibility, crushing resistance of shells, areal density, size, and depth in the sediments on the relative foraging value of exotic P. amurensis vs. the formerly dominant native clam Macoma balthica. P. amurensis, including shells, had higher nitrogen and energy content per clam of the same length class, and higher digestibility of energy, than M. balthica. Gut retention time did not differ between clam species, so their relative profitability for scaup was determined mainly by the intake rate of digestible nutrients during short, costly dives. For scaup foraging in an aquarium 1.8 m deep, intake rates (number of prey per second) of food items buried in sand-filled trays increased with increasing prey density up to at least 4000 prey/m2. For items buried 3 cm deep, intake rates did not differ for prey \u3c6 mm long vs. prey\u3e6–12 mm long; however, intake rates were much lower when prey were deeper in the sediments (6 cm vs. 3 cm). In the field, a much higher percentage of P. amurensis were in the length range most commonly eaten by Lesser Scaup (\u3c12 \u3emm), and unlike M. balthica, almost all P. amurensis were in the top 5 cm of sediments where scaup intake rates are highest. In tensometer measurements, shells of P. amurensis were much harder to crush than shells of M. balthica, which might partly offset the apparent energetic advantages of P. amurensis. In many respects, the exotic P. amurensis appears to be a more valuable food than the native M. balthica for Lesser Scaup. However, because P. amurensis accumulates much higher levels of some contaminants, this exotic invasion increases the risk of toxicity to scaup and a range of other benthic predators

Characteristics of Waterfowl Harvest at Horseshoe Lake, Madison County, Illinois

Division of Wildlife Resources Migratory Bird Section, Periodic Report No. 13Report issued on: April 21, 197

Priority sites for wildfowl conservation in Mexico

A set of priority sites for wildfowl conservation in Mexico was determined using contemporary count data (1991–2000) from the U.S. Fish & Wildlife Service mid-winter surveys. We used a complementarity approach implemented through linear integer programming that addresses particular conservation concerns for every species included in the analysis and large fluctuations in numbers through time. A set of 31 priority sites was identified, which held more than 69% of the mid-winter count total in Mexico during all surveyed years. Six sites were in the northern highlands, 12 in the central highlands, six on the Gulf of Mexico coast and seven on the upper Pacific coast. Twenty-two sites from the priority set have previously been identified as qualifying for designation as wetlands of international importance under the Ramsar Convention and 20 sites are classified as Important Areas for Bird Conservation in Mexico. The information presented here provides an accountable, spatially-explicit, numerical basis for ongoing conservation planning efforts in Mexico, which can be used to improve existing wildfowl conservation networks in the country and can also be useful for conservation planning exercises elsewhere

Review of Seabird Demographic Rates and Density Dependence. JNCC Report no. 552

Introduction This report presents individual species accounts for a selection of British seabirds, sea ducks, divers and grebes. Each account gathers the most up to date published estimates on the following demographic parameters: age-specific survival, age-specific productivity, age of recruitment, incidence of missed breeding, and natal and adult breeding dispersal. Particular attention has been given to regional variation in demographic rates, indicating the extent to which estimates may be applied to other less-well studied colonies. Where possible, the intrinsic and extrinsic factors that influence demographic rates are also detailed. The reported rates should enable population models that assess the impacts of offshore wind farms to be developed as reliably and realistically as possible. Where sufficient data could not be gathered using UK examples, data from colonies outside of the UK have been presented, or a proxy species has been identified. The evidence for density-dependent regulation of seabird demographic rates is also reviewed using examples from the UK, as well as non-UK studies on similar species

Birds of the North Gulf Coast - Prince William Sound Region, Alaska

The North Gulf Coast - Prince William Sound region of Alaska, phytographically, lies at the northern limit of the Sitka Spruce-hemlock coastal/subalpine forests of the Pacific Coast; it includes approximately 178,500 km2 and a shoreline of approximately 8,500 km. Fourteen habitats are utilized by birds: tundra; shrub thickets; hemlock-Sitka Spruce forests; bogs; mixed deciduous-spruce woodlands; marshes; lacustrine waters; fluviatile waters; cliffs, bluffs, and screes; moraines, alluvia, and barrier islands; beaches and tidal flats; rocky shores and reefs; inshore waters; and offshore waters. Two hundred nineteen species of birds have been recorded in the region, 111 of which are primarily water-related. Status, abundance, habitat, and seasonal occurrence are discussed in the annotated list of species. The geographic location and restrictive topography of the region make it a spectacular corridor for millions of migrating birds. In spring millions of Pintails, Dunlins, Western Sandpipers, and Northern Phalaropes move through the region, as do tens of thousands of Whistling Swans, Snow Geese, Knots, and Sanderlings. Fall concentrations of White-fronted Geese and Sandhill Cranes may exceed 100,000's. Species with notably large summering populations include Trumpeter Swans (several hundred breeding pairs), Bald Eagles (1,800-2,000 breeding pairs), Aleutian Terns (150-250 breeding pairs on Copper River Delta), Marbled Murrelets (probably millions), and Kittlitz's Murrelets (probably a few 100,000's). Significant range extensions reported include Yellow-billed Loons (fairly common in winter), Pink-footed and Pale-footed shearwaters, Brandt's Cormorants (breeding), Red-faced Cormorants (breeding), Steller's Eiders (winter), Bristle-thighed Curlews (migrant), Bar-tailed Godwits (migrant), Crested Auklets (winter), and northernmost wintering populations of waterfowl (Canada Geese, Gadwalls, Pintails, Green-winged Teals, American Widgeons) and shorebirds (Surfbirds, Black Trunstones, Dunlins, and Sanderlings). Some unexpected species reported include Skua, Anna's Hummingbird, Purple Marin, Yellowthroat, Common Grackle, and White-throated Sparrow

NOU Spring Field Days and Annual Meeting, Kimball, May 20–22, 2016

The annual meeting of the Nebraska Ornithologists\u27 Union was held at the Kimball Event Center on May 20–22, 2016, and was organized by Robin Harding and Betty Grenon. Although it was a long drive for most, 75 birders attended, including guests from Iowa, South Dakota, Wyoming, Colorado, and Arkansas. On Friday evening, President Dan Leger presented a Michael Forsberg photograph of Burrowing Owls to Betty Grenon in appreciation for her many years of service as Treasurer. The evening program continued with a presentation by Angela Dwyer and Larry Snyder of the Bird Conservancy of the Rockies, formerly known as the Rocky Mountain Bird Observatory. The Bird Conservancy and Nebraska Prairie Partners are responsible for implementing the Mountain Plover nest protection program. They began counting Mountain Plovers in 2001 and later created a nest incentive program with modest payments to landowners who are willing to have plover nests in their agricultural fields marked with stakes to prevent tillage of that area of the field. Approximately 5% of the total population of 12,500 Mountain Plovers nests in Nebraska and the species is listed as Near Threatened by the International Union for Conservation of Nature. The birds often construct two nest scrapes. The female lays a clutch of eggs in one, leaves the male to incubate that one, and then goes on to lay another clutch in the second scrape, which she then incubates. Field trips on Saturday and Sunday morning were led by Kathy DeLara, Bill Flack, Dave Heidt, Wayne Mollhoff, and Don and Janis Paseka. Destinations included Gotte Park in Kimball, Oliver Reservoir, Bushnell, I-80 Exit 1, the Pine Bluffs area in Wyoming, Mountain Plover nests south of Kimball, Golden Eagle nest south of Potter, Hackberry Canyon, Pumpkin Creek, Wildcat Hills State Recreation Area, Scottsbluff sewage lagoons, and Wright\u27s Gap Road. Total species count for the weekend meeting was 156

Body Composition, Parasite Loads, and Blood Parameters of Spring-migrating Lesser Scaup in the Upper Midwest

The abundance and relative composition of helminth communities in the lower gut of LESC differed among regions. Total helminths and % trematodes increased and % cestodes decreased with increasing latitude. Measures of scaup health differed by region, and generally decreased with increasing latitude. Perturbations in health parameters that can be associated with infectious disease or other health insult (e.g., PCV, increased lymphocytes, reduced heterophil/lymphocyte ratios, reduced monocytes) reflected the geographic pattern of infection with the highly pathogenic trematode Sphaeridiotrema pseudoglobulus. However, some exceptions were apparent and may reflect the combined effects of healthy and infected birds. For example, CMRV included LESC from Mississippi River pool 19, considered high quality habitat, and pool 12, where ducks were infected with S. pseudoglobulus. Patterns of variation in measures of condition were less clear. For example, fresh mass of LESC increased with latitude, with the exception of ducks from UMRV in 2014. This was reflected in lower carcass lipids, triglycerides and NEFA and increased BHB in that sample. Ducks collected from IRV were in poorer condition in 2015 than 2014, judging by a decline in carcass lipids without a concomitant decrease in mass. These results suggest interactions between annual wetland conditions (i.e., food availability) and infectious disease agents (highly-pathogenic intestinal helminths). In the sequel, we intend to further explore these patterns and interrelationships with the addition of the outstanding 2015 LESC health data, helminth community analyses, and incorporation of wetland quality indices.IDNR Division of Wildlife RC09-13FWUIUCunpublishednot peer reviewe