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James R. Lovvorn,
Ph.D. Department of
Zoology and Physiology Tel: (307)766-6100
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Current Research Interests
My group seeks to understand linkages between mobile top predators (birds) and aquatic food webs. We use simulation models to link field and laboratory studies of the foraging energetics of birds with the quality and dispersion of prey, and to predict prey availability as a function of food web interactions. Components of this work include
· Laboratory, field, and modeling studies of the costs of locomotion and thermoregulation in diving birds, and their intake rates for different species, sizes, and densities of prey.
· Field sampling, stable-isotope, fatty acid, and modeling studies of primary production and food web pathways in saline lakes, estuarine bays, and shallow polar seas.
· Using these results to delineate viable foraging habitat for mobile predators, and to predict how those areas will shift as prey and competing predators respond to environmental variations.
Ongoing Projects
Climate-driven changes in impacts of benthic predators in the northern Bering Sea
Water temperatures in the northern Bering Sea are increasing with climate warming, and the distributions of a suite of bottom predators – fish, crabs, sea stars, and gastropods – are moving northward. We are identifying the distributions, diets, and growth patterns of these predators, and evaluating their impacts on benthic food webs that are critical to federally threatened Spectacled Eiders that winter in this region.
For diet studies, we are using gut contents, stable isotopes, and fatty acids to characterize the diets of component animals and to construct food web networks. We are also using these methods to assess the importance of bacteria vs. freshly deposited phytoplankton to deposit-feeders that are prey for higher predators, a routing that might change with loss of ice cover and the associated ice-edge spring bloom. Our analyses will indicate whether benthic food webs in this area are under bottom-up vs. top-down control, and how the relative importance of these controls may change with reduction in sea ice.
The individual-based model allowing evaluation of the impacts of food web changes on eiders is based on over a decade of work on captive birds, and on biomechanical analyses of free-ranging birds carrying time-at-depth recorders. Integration of this model for eiders with long-term data on the dispersion of benthic assemblages isl indicating how the location and extent of viable habitat for eiders has changed over time. The food web work over a large geographic area will aid in predicting the trajectory of viable eider habitat with changing climate.
-- Graduate students Paul Kaseloo, Samantha Richman, Joseph Bump, Jason Kolts, and Chris North
Costs of diving by wing and foot propulsion in ducks, and effects of body size on thresholds of foraging proifitability
Models of the cost of diving in birds require knowledge of their energy efficiency in underwater swimming. We are measuring the reduction in energy use by White-winged Scoters swimming by wings and feet together as opposed to feet only. Our data suggest that using wings in addition to feet reduces the cost of descent by about 34%, an important consideration for eiders diving to depths of 40 to 70 m to feed on benthic prey. This large savings might result from greater mechanical efficiency of lift-based propulsors, as well as greater replacement of heat lost to water by heat from both wing and leg muscles.
An important need in conservation planning is to estimate the area of habitat capable of supporting different species, including the threshold prey densities they require. In making such estimates, it is often assumed theoretically that larger animals need larger areas of habitat; however, within foraging guilds of birds the opposite is often true. Understanding this anomaly is generally stymied by lack of data on effective prey availability, and on how prey availability affects foraging success. However, for two diving duck species that differ in body size but feed on the same bivalve prey (White-winged Scoter and Lesser Scaup), we have detailed laboratory data on costs of diving and intake rates per unit time for different sizes, burial depths, and densities of infaunal prey. We are finding that a lower fraction of the same prey is available to smaller scaup than to larger scoters, so that scaup will run out of food sooner than scoters. Thus, included niche theory may be an important conceptual tool in understanding trends of habitat needs of birds of different sizes.
-- Graduate student Samantha Richman
Developing foraging models to relate the distribution of Cassin’s Auklets to their krill prey in the Channel Islands, California
Impacts of oil spills may be especially important when interacting with other environmental changes that have jeopardized a population. Cassin’s Auklets (CAAU) were once the second most abundant seabird breeding in California, but from 1985 to 1994, the breeding population on the central California coast declined by 87% from 62,000 to 8,000 birds. They have not recovered since, and reached a 35-year low with nearly total breeding failure in 2005 and 2006. This decline has apparently resulted from effects of ocean conditions on foraging energetics, by altering prey abundance and the distance of feeding areas from colonies. About 20% of this population now nests in the Channel Islands, where they feed in a limited area mostly in and near a shipping lane for oil tankers.
In this project, we are measuring the costs of diving in captive CAAU, for use in estimating relative foraging costs among areas with differing oil-spill risk. Based on daily foraging patterns near oil-transport lanes, we will then model the impacts on energy balance and breeding success of CAAU in the Channel Islands if they were excluded from their main feeding area by an oil spill and cleanup activities. We are also measuring the energy costs of carrying time-at-depth recorders, which can be used to indicate changes in the behavior and energy balance of birds in the field due to oil spills.
From an energetics perspective, this project will also reveal the extent to which heat from exercising muscles replaces heat lost to water at different temperatures in a very small diving bird (~160 g). By comparing such measurements with existing data for diving ducks, we hope to develop general methods for estimating this thermal substitution for use in models of dive costs.
-- Graduate students Paul Kaseloo and Samantha Richman
Characterizing the habitat requirements, and especially the value of herring spawn vs. alternative prey, to Surf and White-winged Scoters in the Puget Sound-Georgia Basin
Like many sea duck species, scoter populations in western North America have declined precipitously for reasons that are poorly understood. We are using gut contents, and stable isotope and fatty acid markers in tissues and blood, to characterize diets of two species of scoters throughout winter and early spring migration in Puget Sound and the Strait of Georgia. By comparing this information to data from telemetry, counts throughout the area, observations of behavior, and benthic sampling, we are determining how habitat dependencies differ between Surf and White-winged Scoters throughout the winter period. Although these poorly studied species are often considered similar, we are finding large differences in diets and seasonal movements that are reflected in body condition. In particular, Surf Scoters appear to be much more dependent on consuming the eggs of spawning herring in spring than are White-winged Scoters, perhaps making observed declines in spawning events in this region of greater consequence for Surf Scoters. Together with extensive sampling of prey availability in different benthic habitats, this information will be used to recommend marine protected areas for these species.
-- Graduate student Eric Anderson
Foraging ecology and environmental contaminants in diving ducks and their benthic prey in San Francisco Bay
Past studies have shown high levels of contaminants, especially selenium, in diving ducks wintering in San Francisco Bay. However, in efforts to identify sites of special concern, contaminant levels in birds collected at a given site are often poorly correlated with contaminant levels in their prey at the same site. This discrepancy probably results from frequent movement among areas by these highly mobile birds. We are developing an individual-based model for scaup ducks that integrates measurements of energy costs and food intake in captive birds with field data on diets, foraging behavior, movements of radio-tagged birds, and metal contaminants in birds and prey collected at multiple feeding sites. This model will indicate how movement of birds among sites affects inference about local contamination based on birds and prey collected at particular sites. The model will also allow prediction of the effects of cleaning up particular sites on overall exposure levels of the birds.
-- Graduate students Victoria Poulton, Paul Kaseloo, and Samantha Richman
Long-term variations in food webs of irrigation-dependent wetlands in an arid landscape
In the Laramie Basin of southeast Wyoming, many saline wetlands are associated with irrigation systems driven by snowpack in adjacent mountains. Depending on whether wetlands receive freshwater inflow anually or less frequently, wetlands shift from oligosaline systems surrounded by bulrush to mesosaline systems surrounded by unvegetated mudflat. Submersed vegetation shifts from dominance by the macroalga Chara to dominance by sago pondweed. Invertebrate communities shift from dominance by amphipods and snails with few insect predators to dominance by chironomid larvae with abundant insect predators. In all cases the food webs appear to be driven mainly by epiphytic algae and their exudates. We seek to understand these community shifts in terms of geochemical tolerances, wetland permanence relative to invertebrate dispersal capabilities, and internal food web interactions. Models of water delivery throughout the Laramie Basin over the last 50 years are being used to evaluate effects of variations in snowpack on the dispersion of different wetland habitats for birds throughout the Basin.
Selected Publications
♦ Corcoran, R. M., J. R. Lovvorn, and P. J.Heglund. 2008. Long-term change in limnology and invertebrate communities in Alaskan boreal wetlands. Hydrobiologia, in press.
♦ Anderson, E. M., J. R. Lovvorn, and M. T. Wilson. 2008. Reevaluating marine diets of Surf and White-winged Scoters: interspecific differences and the importance of soft-bodied prey. Condor, in press.
♦ Anderson, E. M., and J. R. Lovvorn. 2008. Gray whales may increase feeding opportunities for avian benthivores. Marine Ecology Progress Series 360:291-296.
♦ Richman, S. E., and J. R. Lovvorn. 2008. Costs of diving by wing and foot propulsion in a sea duck, the White-winged Scoter. Journal of Comparative Physiology B 178:321-332.
♦ Doak, D. F., J. E. Estes, B. S. Halpern, U. Jacob, D. R. Londberg, J. R. Lovvorn, D. H. Monson, M. T. Tinker, T. M. Williams, J. T. Wooton, I. Carroll, M. Emmerson, F. Micheli, and M. Novak. 2008. Understanding and predicting ecological dynamics: are major surprises inevitable? Ecology 89:952-961.
♦ Lovvorn, J. R. 2007. Thermal substitution and aerobic efficiency: measuring and predicting effects of heat balance on endotherm diving energetics. Philosophical Transactions of the Royal Society of London B 362:2079-2093.
♦ Corcoran, R. M., J. R. Lovvorn, M. R. Bertram, and M. T. Vivion. 2007. Lesser Scaup nest success and duckling survival on the Yukon Flats, Alaska. Journal of Wildlife Management 71:127-134.
♦ Kaseloo, P. A., and J. R. Lovvorn. 2006. Substitution of heat from exercise and digestion by ducks diving for mussels at varying depths and temperatures. Journal of Comparative Physiology B 176:265-275.
♦ Watanuki, Y., S. Wanless, M. Harris, M. Miyazaki, J. R. Lovvorn, H. Tanaka, and K. Sato. 2006. Regulation of stroke patterns in wing propelled divers: a comparison among alcids and a penguin. Journal of Experimental Biology 209:1217-1230.
♦ Lovvorn, J. R., L. W. Cooper, M. L. Brooks, C. C. De Ruyck, J. K. Bump, and J. M. Grebmeier. 2005. Organic matter pathways to zooplankton and benthos under pack ice in late winter and open water in late summer in the north-central Bering Sea. Marine Ecology Progress Series 291:135-150.
♦ Hart, E. A., and J. R. Lovvorn. 2005. Patterns of macroinvertebrate abundance in inland saline wetlands: a trophic analysis. Hydrobiologia 541:45-54.
♦ Kaseloo, P. A., and J. R. Lovvorn. 2005. Effects of surface activity patterns and dive depth on thermal substitution in fasted and fed Lesser Scaup ducks. Canadian Journal of Zoology 83:301-311.
♦ Peck, D. E., D. M. McLeod, J. R. Lovvorn, and J. P. Hewlett. 2005. Irrigation-dependent wetlands vs. instream flow enhancement: economics of water transfers from agriculture to wildlife uses. Environmental Management 34:842-855.
♦ Lovvorn, J. R., Y. Watanuki, A. Kato, Y. Naito, and G. A. Liggins. 2004. Stroke patterns and regulation of swim speed and energy cost in free-ranging Brünnich's Guillemots. Journal of Experimental Biology 207:4679-4695.
♦ Bump, J. K., and J. R. Lovvorn. 2004. Effects of lead structure in Bering Sea pack ice on the flight costs of wintering Spectacled Eiders. Journal of Marine Systems 50:113-139.
♦ Richman, S. E., and J. R. Lovvorn. 2004. Relative foraging value to Lesser Scaup ducks of native and exotic clams from San Francisco Bay. Ecological Applications 14:1217-1231.
♦ Poulton, V. K., J. R. Lovvorn, and J. Y. Takekawa. 2004. Spatial and overwinter changes in clam populations of San Pablo Bay, a semiarid estuary with highly variable freshwater inflow. Estuarine, Coastal and Shelf Science 59:459-473.
♦ Lovvorn, J. R., and E. A. Hart. 2004. Irrigation, salinity, and landscape patterns of natural palustrine wetlands. Pages 105-129 in M. C. McKinstry, W. A. Hubert, and S. H. Anderson, eds. Wetland and riparian areas of the Intermountain West: ecology and management. Univ. of Texas Press, Austin. 330 pp.
♦ Hart, E. A., and J. R. Lovvorn. 2003. Algal vs. macrophyte inputs to food webs of inland saline wetlands. Ecology 84:3317-3326.
♦ Richman, S. E., and J. R. Lovvorn. 2003. Effects of clam species dominance on nutrient and energy acquisition by Spectacled Eiders in the Bering Sea. Marine Ecology Progress Series 261:283-297.
♦ Lovvorn, J. R, S. E. Richman, J. M. Grebmeier, and L. W. Cooper. 2003. Diet and body condition of Spectacled Eiders wintering in pack ice of the Bering Sea. Polar Biology 26:259-267.
♦ Kaseloo, P. A., and J. R. Lovvorn. 2003. Heat increment of feeding and thermal substitution in Mallard ducks feeding voluntarily on grain. Journal of Comparative Physiology B 173:207-213.
♦ Kruse, K. L., J. R. Lovvorn, J. Y. Takekawa, and J. Mackay. 2003. Winter distribution and survival of a high-desert breeding population of Canvasbacks. Condor 105:791-804.
♦ Kruse, K. L., J. R. Lovvorn, J. Y. Takekawa, and J. Mackay. 2003. Long-term productivity of Canvasbacks (Aythya valisineria) in a snowpack-driven desert marsh. Auk 120:107-119.
♦ Poulton, V. K., J. R. Lovvorn, and J. Y. Takekawa. 2002. Clam density and scaup feeding behavior in San Pablo Bay, California. Condor 104:518-527.
♦ Hart, E. A., and J. R. Lovvorn. 2002. Interpreting stable isotopes from macroinvertebrate foodwebs in saline wetlands. Limnology and Oceanography 47:580-584.
♦ Lovvorn, J. R., and G. A. Liggins. 2002. Interactions of body shape, body size and stroke-acceleration patterns in costs of underwater swimming by birds. Functional Ecology 16:106-112.
♦ Cooper, L. W., J. M. Grebmeier, I.L. Larsen, V. G. Egorov, C. Theodorakis, H. P. Kelly, and J. R. Lovvorn. 2002. Seasonal variation in sedimentation of organic materials in the St. Lawrence Island polynya region, Bering Sea. Marine Ecology Progress Series 226:13-26.
♦ Baduini, C. L., J. R. Lovvorn, and G. L. Hunt. 2001. Determining the nutritional condition of Short-tailed Shearwaters (Puffinus tenuirostris): implications for migratory flight ranges and starvation events. Marine Ecology Progress Series 222:265-277.
♦ Lovvorn, J. R., C. L. Baduini, and G. L. Hunt. 2001. Modeling underwater visual and filter feeding by planktivorous shearwaters in unusual sea conditions. Ecology 82:2342-2356.
♦ Peck, D. E., and J. R. Lovvorn. 2001. The importance of flood irrigation in water supply to wetlands in the Laramie Basin, Wyoming, USA. Wetlands 21:370-378.
♦ Lovvorn, J. R. 2001. Upstroke thrust, drag effects, and stroke-glide cycles in wing-propelled swimming by birds. American Zoologist 41:154-165.
♦ Lovvorn, J. R., G. A. Liggins, M. H. Borstad, S. M. Calisal, and J. Mikkelsen. 2001. Hydrodynamic drag of diving birds: effects of body size, body shape and feathers at steady speeds. Journal of Experimental Biology 204:1547-1557.
♦ Hart, E. A., and J. R. Lovvorn. 2000. Vegetation dynamics and primary production in saline, lacustrine wetlands of a Rocky Mountain basin. Aquatic Botany 66:21-39.
♦ Lovvorn, J. R., Yule, D., and C. E. Derby. 1999. Greater predation by Double-crested Cormorants on cutthroat versus rainbow trout fingerlings stocked in a Wyoming river. Canadian Journal of Zoology 77: 1984-1990.
♦ Lovvorn, J. R., D. A. Croll, and G. A. Liggins. 1999. Mechanical versus physiological determinants of swimming speeds in diving Brünnich's Guillemots. Journal of Experimental Biology 202:1741-1752.
♦ Lovvorn, J. R., W. M. Wollheim, and E. A. Hart. 1999. High Plains wetlands of southeast Wyoming: salinity, vegetation, and invertebrate communities. In D. Batzer, R. B. Rader, and S. A. Wissinger, eds. Invertebrates in freshwater wetlands of North America: ecology and management. Van Nostrand Reinhold, New York. In press.
♦ Derby, C. E., and J. R. Lovvorn. 1997. Predation on fish by cormorants and pelicans in a cold-water river: a field and modeling study. Canadian Journal of Fisheries and Aquatic Sciences 54:1480-1493.
♦ Lovvorn, J. R., and J. R. Baldwin. 1996. Intertidal and farmland habitats of ducks in the Puget Sound region: a landscape perspective. Biological Conservation 77:97-114.
♦ Lovvorn, J. R., and M. P. Gillingham. 1996. Food dispersion and foraging energetics: a mechanistic synthesis for field studies of avian benthivores. Ecology 77: 435-451.
♦ Lovvorn, J. R., and M. P. Gillingham. 1996. A spatial energetics model of cadmium accumulation by diving ducks. Archives of Environmental Contamination and Toxicology 30:241-251.
♦ Wollheim, W. M., and J. R. Lovvorn. 1996. Effects of macrophyte growth forms on invertebrate communities in saline lakes of the Wyoming High Plains. Hydrobiologia 323:83-96.
♦ Wollheim, W. M., and J. R. Lovvorn. 1995. Salinity effects on macroinvertebrate assemblages and waterbird food webs in shallow lakes of the Wyoming High Plains. Hydrobiologia 310:207-223.
♦ Lovvorn, J. R. 1994. Biomechanics and foraging profitability: an approach to assessing trophic needs and impacts of diving ducks. Hydrobiologia 279/280:223-233.
♦ Lovvorn, J. R., and D. R. Jones. 1994. Biomechanical conflicts between diving and aerial flight in estuarine birds. Estuaries 17:62-75.
♦ Lovvorn, J. R. 1994. Nutrient reserves, probability of cold spells and the question of reserve regulation in wintering Canvasbacks. Journal of Animal Ecology 63:11-23.
♦ Baldwin, J. R., and J. R. Lovvorn. 1994. Major expansion of seagrass habitat by the exotic Zostera japonica, and its use by dabbling ducks and Brant in Boundary Bay, British Columbia. Marine Ecology Progress Series 103:199-127.
♦ Baldwin, J. R., and J. R. Lovvorn. 1994. Habitats and tidal accessibility of the marine foods of dabbling ducks and Brant in Boundary Bay, British Columbia. Marine Biology 120:627-638.
