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The Winter Ecology of the Coastal Plain Swamp Sparrow
My PhD research examines the tidal marsh endemic Coastal Plain Swamp Sparrow (CPSS, Melospiza georgiana nigrescens) on its recently identified winter grounds in Eastern North Carolina (Greenberg et al. 2007). There, the CPSS overlaps with 1–2 other subspecies (M. g. georgiana and possibly M. g. ericrypta), which I lump into "Inland Swamp Sparrows" (INSS). Discrimination of CPSS and INSS is possible by plumage characteristics and bill size (Greenberg et al. 2008). In addition, I am developing subspecies-specifc stable isotope signatures from feathers. The main questions of my research are:
1) Is the CPSS better adapted to the tidal marsh than the INSS in the winter?
I am answering this with a comparative study made possible by the subspecies' winter sympatry.
2) Is food abundance limiting the survival and reproductive success of these subspecies?
I will answer this with a food supplementation experiment.
I am part of a group of Swamp Sparrowologists centered at the Smithsonian Migratory Bird Center, who are trying to piece together the year-round ecology and evolution of the CPSS. Read more here.
Swamp Sparrow
2009 American Ornithologists' Union Poster (3 MB)
Field Housing
The Ecology and Management of Invasive Mammals in Hawaii
Invasive mammals can have devestating effects on ecosystems, especially on islands. Colleagues and I study the ecology of mammals on Mauna Kea and Mauna Loa mountains, Hawaii Island, their effects on native species, and techniques to manage these mammals. Feral cats (Felis catus) are abundant and destroy 11% of the nests of the critically endangered Palila bird (Loxioides bailleui; Hess et al. 2004). We recently found that the cats experience high survival and longevity (Danner et al. In Press), based on an age distribution of several individuals aged by dental cementum lines. Radio-tracking data show that individual cats have expansive home ranges, with males occupying almost two times as much area as females, and that most individuals move more than 100m per day (Goltz et al. 2008). Since feline diseases may spread to other species or limit cat populations, we assessed the prevalence of three diseases: Toxoplasmosis (caused by the parasite Toxoplasma gondii), Feline Immunodeficiency Virus (FIV), and Feline Leukemia Virus (FeLV). We found a high prevalence of T. gondii (Danner et al. 2007), which is passed to and has killed multiple Hawaiian bird species (Work et al. 2000, 2002) and a critically endangered Hawaiian monk seal (Honnold et al 2005). In addition, feral cats remain abundant despite carrying FIV and FeLV (Danner et al. 2007), both of which are hypothesized biological control agents.
Invasive mouflon sheep (Ovis gmelini musimon) are abundant on Mauna Loa and Mauna Kea, and threaten native plants and subsequently native animals through habitat destruction. We found Mauna Loa mouflon to have relatively high annual survival despite heavy control (Hess et al. Submitted). We estimated survival based on an age distribution of several individuals aged by dental cementum lines. In addition, we found that aging via cementum lines is accurate in mouflon sheep and better than other aging methods by offering applicability over age three and greater precision.
References
Hess, S.C., R.M. Stephens, T.T. Thompson, R.M. Danner, and B. Kawakami Jr. Submitted. Survival of European mouflon on Mauna Loa, Hawai'i, based on tooth cementum lines.
Danner, R.M., C.A. Farmer, S.C. Hess, R.M. Stephens, and P.C. Banko. In Press. Survival of feral cats, Felis catus (Carnivora: Felidae), on Mauna Kea, Hawai`i, based on tooth cementum lines. Pacific Science 63(3)
Danner, R.M., D.M. Goltz, S.C. Hess, and P.C. Banko. 2007. Evidence of Feline Immunodeficiency Virus, Feline Leukemia Virus, and Toxoplasma gondii in Feral Cats on Mauna Kea, Hawaii. Journal of Wildlife Diseases 43:315–318.
Goltz, D.M., S.C. Hess, K.W. Brinck, P.C. Banko, and R.M. Danner. 2008. Home range and movements of feral cats on Mauna Kea, Hawaii. Pacific Conservation Biology. 14:177–184
Greenberg, R., P. P. Marra, and M. J. Wooller. 2007. Stable-isotope (C, N, H) analysis help locate the winter range of the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens). Auk 124:1137–1148.
Greenberg, R., B. Olsen, B. Ballentine, S. Warner, and R. Danner. 2008. Temporal distribution of the Coastal Plain Swamp Sparrow: The importance of field identification. Birding 40(3):42–49.
Hess, S.C., P.C. Banko, D.M. Goltz, R.M. Danner, and K.W. Brinck. 2004. Strategies for reducing feral cat threats to endangered Hawaiian Birds. Proc. 21st Vertebrate Pest Conference. R.M. Timm and W.P. Gonzalez, Eds. Univ. of Calif., Davis. Pp. 21–26.
Honnold, S. P., R. Braun, D. P. Scott, C. Sreekumar, and J. P. Dubey. 2005. Toxoplasmosis in a Hawaiian monk seal (Monachus schauinslandi). Journal of Parasitology 91:695–697.
Work, T. M., J. G. Massey, B. A. Rideout, C. H. Gardiner, D. B. Ledig, O. C.H. Kwok, and J. P. Dubey. 2000. Fatal toxoplasmosis in free-ranging endangered `Alala from Hawaii. Journal of Wildlife Diseases 36:205–212.
Work, T. M., J. G. Massey, D. S. Lindsay, and J. P. Dubey. 2002. Toxoplasmosis in three species of native and introduced Hawaiian birds. Journal of Parasitology 88:1040–1042.