Hematology, Plasma Chemistry, and Serology of the Flightless Cormorant (Phalacrocorax Harrisi) in the Gala´ Pagos Islands, Ecuador
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Journal of Wildlife Diseases, 42(1), 2006, pp. 133–141 # Wildlife Disease Association 2006 HEMATOLOGY, PLASMA CHEMISTRY, AND SEROLOGY OF THE FLIGHTLESS CORMORANT (PHALACROCORAX HARRISI) IN THE GALA´ PAGOS ISLANDS, ECUADOR Erika K. Travis,1,2,7 F. Hernan Vargas,3 Jane Merkel,1,5 Nicole Gottdenker,6 R. Eric Miller,1 and Patricia G. Parker1,5 1 Saint Louis Zoo, One Government Dr., Saint Louis, Missouri 63110, USA 2 College of Veterinary Medicine, University of Missouri, 203 Veterinary Medicine Building, Columbia, Missouri 65211, USA 3 Wildlife Conservation Research Unit, University of Oxford, Tubney House, Abingdon Road, OX13 5QL, UK 4 Charles Darwin Research Station, Puerto Ayora, Santa Cruz Island, Gala´pagos, Ecuador 5 Department of Biology, University of Missouri–Saint Louis, 8001 Natural Bridge Road, Saint Louis, Missouri 63121, USA 6 Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA 7 Corresponding author (email: [email protected]) ABSTRACT: The flightless cormorant (Phalacrocorax harrisi) is an endemic species of the Gala´pagos Islands, Ecuador. Health studies of the species have not previously been conducted. In August 2003, baseline samples were collected from flightless cormorant colonies on the islands of Isabela and Fernandina. Seventy-six birds, from nestlings to adults, were evaluated. Genetic sexing of 70 cormorants revealed 37 females and 33 males. Hematology assessment consisted of packed cell volume (n519), leukograms (n569), and blood smear evaluation (n569). Microscopic evaluation of blood smears revealed microfilaria in 33% (23/69) of the cormorants. Plasma chemistries were performed on 46 cormorants. There was no significant difference in chemistry values or complete blood counts between male and female cormorants or between age groups. Based on a serologic survey to assess exposure to avian pathogens, birds (n569) were seronegative for West Nile virus, avian paramyxovirus type 1 (Newcastle disease virus), avian paramyxovirus types 2 and 3, avian influenza, infectious bursal disease, infectious bronchitis, Marek’s disease (herpes), reovirus, avian encephalomyelitis, and avian adenovirus type 2. Antibodies to avian adenovirus type 1 and Chlamydophila psittaci were found in 31% (21/68) and 11% (7/65) of flightless cormorants respectively. Chlamydophila psittaci was detected via polymerase chain reaction in 6% (2/33) of the cormorants. The overall negative serologic findings of this research suggest that the flightless cormorant is an immunologically na¨Ive species, which may have a reduced capacity to cope with the introduction of novel pathogens. Key words: Chemistry, flightless cormorant, Gala´pagos Islands, health survey, hematology, microfilariae, Phalacrocorax harrisi, serology. INTRODUCTION (Houvenaghel, 1984). The species is con- sidered endangered due to its small The Gala´pagos archipelago is located in distributional range and the extreme the Pacific Ocean, on the equator, fluctuations in the number of mature 1,000 km west of continental Ecuador. birds (BirdLife International, 2000). Since Gala´pagos avifauna is comprised of 58 1998, the numbers of flightless cormorants resident species, of which nearly half are have been increasing; their census num- endemic. The flightless cormorant (Phala- bers were 727 in 1998 (Vargas and crocorax harrisi) is an endemic species Wiedenfeld, 2003) and 1,411 in 2004 restricted to two western islands of the (Vargas and Wiedenfeld, 2004). With archipelago, Isabela and Fernandina. The a census representing 83% of the total cormorants prefer the eastern coast of population (Valle, 1994), the 2004 popu- Fernandina and the western coast of lation size is estimated to be at 1,700 Isabela, where there is an upwelling of individuals (Vargas and Wiedenfeld, water due to the cold Cromwell current 2004). While no avian species have and consequently an abundance of fish become extinct from the Gala´pagos Is- 133 134 JOURNAL OF WILDLIFE DISEASES, VOL. 42, NO. 1, JANUARY 2006 lands (Wikelski et al., 2004) and the health study in the Gala´pagos Islands. The flightless cormorants have had a mild aim of the study was to determine population increase in the last few years, hematology and biochemistry parameters, there is concern that disease could devas- exposure to avian pathogens, and overall tate the population. Hawaii is a striking health status. This is the first time this example of an island ecosystem that has information has been compiled and base- suffered great losses in endemic avian line data for the endangered free-ranging populations, several at least partly attribut- flightless cormorant is reported. able to the introduction of exotic diseases (Warner, 1968; Van Riper et al., 1986). MATERIALS AND METHODS Endemic avian species of the Gala´pagos Study area and sample collection Islands have been exposed to introduced pathogens, but these introductions have Flightless cormorants are found on the islands of Isabela (0u259300S, 91u79W) and not been directly correlated to population Fernandina (0u22900S, 91u319200W) in the decline. A large, ongoing, comprehensive Gala´pagos Islands. All sampling procedures avian health study in the Gala´pagos were in accordance with Saint Louis Zoo Islands has been in place since 2001. institutional animal care and use committee Since then, domestic chickens have been standards, and the project was a collaboration between the Saint Louis Zoo, the University of found seropositive for avian adenovirus Missouri–Saint Louis, the Charles Darwin type I, avian encephalomyelitis virus, avian Research Station, the Gala´pagos National paramyxovirus type 1 (Newcastle disease Park, and the University of Oxford. Over virus), infectious bronchitis virus, infec- 4 days in August 2003, 76 cormorants were tious bursal disease virus, reovirus, Myco- visually evaluated to determine health status. These animals were classified as 8% (6/76) plasma sp. and Chlamydophila psittaci nestlings, 32% (24/76) juveniles, and 61% (46/ (Gottdenker et al., 2005). Antibodies to 76) adults. The animals were aged by plumage avian adenovirus type I and avian enceph- and eye color (Snow, 1966; Harris, 1979). The alomyelitis virus have been reported from cormorants were relatively sedentary on land, waved albatrosses (Phoebastria irrorata) facilitating net or hand catches, and they were sampled in a small dinghy or on land. Seventy- endemic to Espan˜ ola Island (Padilla et al., three flightless cormorants were manually 2003). On several islands in the Gala´pagos restrained for a brief physical examination, archipelago, endemic Gala´pagos doves measurement of morphometric parameters, (Zenaida galapagoensis) have been posi- transponder placement, and sample collection. Morphometric measurements of bill length, tive for a Haemoproteus sp. and for C. width, and depth were taken with a caliper and psittaci, while introduced rock doves body weights were measured to the nearest 50 (Columba livia) have been positive for g with a hand-held 5-kg spring scale (PesolaH, Trichomonas gallinae (Padilla et al., 2004). Baar, Switzerland) (Vargas, unpubl. data). A Furthermore, avipoxviruses have been transponder (AVID Microchip, Folsom, ´ Louisiana, USA) was placed subcutaneously detected in endemic Galapagos finches over the left dorsal midphalangeal area and the (Geospiza fortis), Gala´pagos mockingbirds skin defect was sealed with tissue glue (3M (Nesomimus parvulus), and yellow war- Vetbond, St. Paul, Minnesota, USA). Veni- blers (Dendroica petechia) on Santa Cruz puncture of the right jugular vein was Island, representing two variants of canar- performed with 20–22-ga needles and 6 ml of blood was collected per bird (n569). Blood ypox virus, while isolates from chickens was immediately placed in lithium heparin represent a distinct fowlpox virus (Thiel et (Vacutainer PST gel, Becton Dickinson, al., 2005). Chickens sampled in 1995 from Franklin Lakes, New Jersey, USA) after inhabited islands of the Gala´pagos were collection (n547), except on the fourth day, infected with Marek’s disease virus (Var- when samples were placed in serum separator tubes (Vacutainer SST gel and clot activator, gas and Snell, 1997). Becton Dickinson) and 0.2 ml was placed in Flightless cormorants were evaluated in lithium heparin (Microtainer gel, Becton August 2003 as part of the ongoing avian Dickinson) (n522). A single sterile swab TRAVIS ET AL.—FLIGHTLESS CORMORANTS IN THE GALAPAGOS 135 (Copan Diagnostics, Corona, California, USA) 1999) was performed at the University of per bird (n570) was used on conjunctival, Missouri–Saint Louis (UMSL). The presence choanal, and cloacal regions. The swab was of C. psittaci antibody was tested via elemen- collected from the sites in the order listed and tary body agglutination (EBA) on plasma stored in cryogenic vials (Nalge Nunc In- (n543) (Grimes et al., 1994) and via direct ternational, Rochester, New York, USA). complement fixation (DCF) on serum (n522) Ectoparasites were visualized on the feathers, (Grimes, 1985), while C. psittaci antigen was manually removed, and placed in cryogenic tested via PCR on conjunctival–choanal–cloa- vials. cal swabs (n533) (Sayada et al., 1995) (Texas Veterinary Medical Diagnostic Laboratory, Sample processing College Station, Texas, USA). Testing for West Nile virus (WNV) was done with plaque Using the whole-blood samples in lithium reduction neutralization (Animal Health Di- heparin, two thin blood smears were prepared, agnostic Center, Cornell University, Ithaca, air dried, and fixed with methanol. Two New