Long-term population monitoring of the Critically Endangered Grenada Dove (<em>Leptotila wellsi</em>) on Grenada, West Indies

Main Article Content

Bonnie L. Rusk

Keywords

Abundance, Endangered, Endemic, Grenada Dove, Leptotila wellsi

Abstract

Abstract The Grenada Dove (Leptotila wellsi) is an IUCN-listed Critically Endangered species endemic to the island of Grenada, West Indies. Long-term population monitoring was carried out episodically between 1987 and 2007 using territory (spot) map­ping. Changes in distribution were also noted through 2016. The most recent population estimate of 136 individuals is based on territorial mapping of 68 males (assuming a 1:1 sex ratio) in 2007, representing a 25% decline from 182 individuals estimated immediately prior to Hurricane Ivan in 2003–2004. The species is limited almost exclusively to two areas in the southwest and on the west coast, with only a few individuals found outside these areas. Major threats include habitat loss and degradation due to residential and commercial development, small-scale agriculture, and fire. The impacts of these threats have been compound­ed by the impacts of extreme weather events such as Hurricane Ivan in 2004, and a high incidence of introduced mammalian predators.

Keywords abundance, endangered, endemic, Grenada Dove, Leptotila wellsi

 

Resumen Monitoreo poblacional a largo plazo de la En Peligro Crítico Paloma de Granada (Leptotila wellsi) en Granada, Caribe Insular—La Paloma de Granada (Leptotila wellsi) es catalogada por la UICN como una especie endémica y En Peligro Crítico en la isla de Granada, en el Caribe Insular. El monitoreo a largo plazo de la población se llevó a cabo de forma episódica entre 1987 y 2007 utilizando el mapeo de territorios (sitios). También se observaron los cambios en la distribución a lo largo de 2016. El esti­mado poblacional más reciente de 136 individuos está basado en el mapeo territorial de 68 machos (asumiendo una proporción de sexos de 1:1) en 2007, lo que representa una disminución del 25% de los 182 individuos estimados inmediatamente antes del huracán Iván en 2003–2004. La especie está limitada casi exclusivamente a dos áreas en el suroeste y la costa oeste, con sólo unos pocos individuos fuera de las mismas. Las principales amenazas incluyen la pérdida y degradación del hábitat para el desa­rrollo urbanístico y comercial, la agricultura a pequeña escala y el fuego. Los efectos de estas amenazas han sido agravados por los impactos de eventos climáticos extremos como el huracán Iván en 2004 y una alta incidencia de mamíferos depredadores.

Palabras clave abundancia, amenazada, endémica, Leptotila wellsi, Paloma de Granada

 

Résumé Surveillance à long terme de la population de la Colombe de Grenade (Leptotila wellsi) En danger critique sur Gre­nade, Antilles—La Colombe de Grenade (Leptotila wellsi) est une espèce endémique à Grenade, dans les Antilles, étiqueté En danger critique par l’UICN. Une étude à long terme de la population a été effectuée épisodiquement entre 1987 et 2007 en utili­sant la cartographie de territoire par secteur. Les changements dans la distribution de la colombe ont également été observés en 2016. L’estimation de la population la plus récente de 136 individus est basée sur une cartographie territoriale de 68 mâles (en supposant un ratio sexuel de 1 : 1) en 2007, ce qui représente une baisse de 25% par rapport à les 182 individus estimés im­médiatement avant l’ouragan Ivan en 2003-2004. L’espèce est limitée presque exclusivement à deux zones dans le sud-ouest et sur la côte ouest de Grenade, avec seulement quelques individus trouvés en dehors de ces zones. Les menaces principales com­prennent la perte et la dégradation de l’habitat pour le développement résidentiel et commercial, l’agriculture à petite échelle, et le feu. Les effets de ces menaces ont été aggravés par les impacts des calamités météorologiques tels que l’ouragan Ivan en 2004 et une forte incidence de mammifères prédateurs introduits.

Mots clés abondance, Colombe de Grenade, en danger, endémique, Leptotila wellsi

Abstract 264 | PDF Downloads 408

References

Allen, G.M. 1911. Mammals of the West Indies. Bulletin of the
Museum of Comparative Zoology 54:175–263.

Atkinson, I.A.E. 1985. The spread of commensal species of Rattus
to oceanic islands and their effects on island avifaunas. Pp.
35–81 in Conservation of Island Birds (P.J. Moors, ed.). International
Council for Bird Preservation Technical Publication no.
3. International Council for Bird Preservation, Cambridge, UK.

Best, L.B. 1975. Interpretational errors in the “mapping method”
as a census technique. Auk 92:452–460.

BirdLife International. 2010. Ecosystem profile: the Caribbean
islands biodiversity hotspot. Prepared for Critical Ecosystem
Partnership Fund, Washington, DC.

BirdLife International. 2013. Small island birds are most at risk
from invasive alien species. datazone.birdlife.org/sowb/
casestudy/small-island-birds-are-most-at-risk-from-invasivealien-
species-.

BirdLife International. 2017. Leptotila wellsi. The IUCN Red List
of Threatened Species 2017:e.T22690874A110630534.

Blockstein, D.E. 1988. Two endangered birds of Grenada, West
Indies: Grenada Dove and Grenada Hook-billed Kite. Caribbean
Journal of Science 24:127–136.

Blockstein, D.E. 1991. Population declines of the endangered
endemic birds on Grenada, West Indies. Bird Conservation International
1:83–91.

Bolton, N.M., C. van Oosterhout, N.J. Collar, and D.J. Bell. 2016.
Population constraints on the Grenada Dove Leptotila wellsi:
preliminary findings and proposals from south-west Grenada.
Bird Conservation International 26:205–213.

Christman, S.P. 1984. Plot mapping: estimating densities of
breeding bird territories by combining spot mapping and transect
techniques. Condor 86:237–241.

Devas, R.P. 1943. Birds of Grenada, St Vincent and the Grenadines.
Carenage Press, St. George's, Grenada.

Donald, P.F. 2007. Adult sex ratios in wild bird populations. Ibis
149:671–692.

Engstrom, R.T., and G.W. Evans. 1990. Hurricane damage to
Red-cockaded Woodpecker (Picoides borealis) cavity trees.
Auk 107:608–610.

Higman, B.W. 2011. A Concise History of the Caribbean. Cambridge
University Press, Cambridge, UK.

Horst, G.R., D.B. Hoagland, and C.W. Kilpatrick. 2001. The mongoose
in the West Indies: the biogeography and population biology
of an introduced species. Pp. 409–424 in Biogeography
of the West Indies: Patterns and Perspectives (C.A. Woods and
F.E. Sergile, eds.). CRC Press, Boca Raton, FL.

Innes, J., D. Kelly, J.M. Overton, and C. Gillies. 2010. Predation
and other factors currently limiting New Zealand forest birds.
New Zealand Journal of Ecology 34:86–114.

Jones, H.P., B.R. Tershy, E.S. Zavaleta, D.A. Croll, B.S. Keitt, M.E.
Finkelstein, and G.R. Howald. 2008. Severity of the effects of
invasive rats on seabirds: a global review. Conservation Biology
22:16–26.

Lack, D., and A. Lack. 1973. Birds on Grenada. Ibis 115:53–59.
Lawrence, G.N. 1884. Characters of a new species of pigeon of
the genus Engyptila from the island of Grenada, West Indies.
Auk 1:180–181.

Long, J.L. 2003. Introduced Mammals of the World: Their History,
Distribution and Influence. CABI Publishing, Wallingford,
UK.

Nelson, H.P., E.S. Devenish-Nelson, M. Geary, A. Lawrence, and
B.L. Rusk. 2015. Report on the re-sampling of the 2004 vegetation
plots of the dry forest Grenada Dove (Leptotila wellsi)
habitat. Unpublished report. Grenada Dove Conservation Programme
and Forestry and National Parks Department, Government
of Grenada, St. George’s, Grenada.

Peters, E.J. 2015. The 2009/2010 Caribbean drought: a case
study. Disasters 39:738–761.

Ralph, C.J., G.R. Geupel, P. Pyle, T.E. Martin, and D.F. DeSante.
1993. Handbook of Field Methods for Monitoring Landbirds.
PSW-GTR-144. Pacific Southwest Research Station, USDA
Forest Service, Albany, CA.

Rivera-Lugo, P.J. 2005. Composition and structure of Grenada
Dove (Leptotila wellsi) habitat. Unpublished report. Grenada
Dry Forest Biodiversity Conservation Project. Government of
Grenada, St. George’s, Grenada.

Rivera-Milán, F.F., P. Bertuol, F. Simal, and B.L. Rusk. 2015. Distance
sampling survey and abundance estimation of the critically
endangered Grenada Dove (Leptotila wellsi). Condor
117:87–93.

Roberts, A.W.P., and L.J. Taylor. 1988. The Grenada Dove expedition.
Unpublished report. University of Reading, Reading, UK.

Rusk, B.L. 1992. The Grenada Dove and the Mt. Hartman Estate:
management recommendations. Unpublished report. Forestry
and National Parks Department, Government of Grenada,
St. George’s, Grenada.

Rusk, B.L. 1998. Status of the endangered endemic Grenada
Dove (Leptotila wellsi) on Grenada, West Indies. Unpublished
report. Forestry and National Parks Department, Government
of Grenada, St. George’s, Grenada.

Rusk, B.L. 2005. Draft post-Hurricane Ivan Grenada Dove evaluation.
Unpublished report. St. George’s, Grenada.

Rusk, B.L. 2008. Grenada Dove census 2007. Unpublished report
for the “Developing the Four Seasons Resort, Grenada” project.
Government of Grenada and Cinnamon88, St. George’s,
Grenada.

Rusk, B.L. 2009. Grenada. Pp. 229–234 in Important Bird Areas
Americas - Priority Sites for Biodiversity Conservation (C. Devenish,
D.F. Díaz Fernández, R.P. Clay, I. Davidson, and I. Yépez
Zabala, eds.). BirdLife International, Quito, Ecuador.

Rusk, B.L. 2010. Mt Hartman development and the Grenada
Dove: finding a win-win solution. Unpublished report. The Nature
Conservancy, St. Thomas, USVI.

Rusk, B.L. 2011. Water sources on the Mt Hartman Estate: management
recommendations for the Grenada Dove. Unpublished
report. Grenada Dove Conservation Programme, St.
George's, Grenada, and American Bird Conservancy, Washington,
DC.

Rusk, B.L. 2015. Predator control for the Grenada Dove. Unpublished
report. Grenada Dove Conservation Programme, St.
George's, Grenada, and American Bird Conservancy, Washington,
DC.

Rusk, B.L., D.E. Blockstein, S.A. Temple, and N.J. Collar. 1998.
Draft recovery plan for the Grenada Dove. Unpublished report
for the Government of Grenada and the World Bank, Washington,
DC.

Rusk, B.L., and L. Clouse. 2004. Status of the endangered endemic
Grenada Dove (Leptotila wellsi). Unpublished report.
Forestry and National Parks Department, Government of Grenada,
St. George’s, Grenada.

Rusk, B.L., and S.A. Temple. 1995. Grenada Dove census, post
habitat loss: west coast. Unpublished report. The World Bank,
Washington, DC.

Rusk, B.L., S.A. Temple, D. Wege, G. Wallace, D.E. Blockstein, G.
Ledec, and L. Sorenson. 2008. Recovery and action plan for
the Grenada Dove. Unpublished draft. Forestry and National
Parks Department, Government of Grenada, St. George’s,
Grenada.

Russell, J.C., J.G. Innes, P.H. Brown, and A.E. Byrom. 2015. Predator-
free New Zealand: conservation country. BioScience 65:
520–525.

Wakeley, J.S. 1987. Avian territory mapping: section 6.3.4, U.S.
Army Corps of Engineers Wildlife Resources Management
Manual. Technical Report EL-87-7. U.S. Army Engineer Waterways
Experiment Station, Vicksburg, MS.

Wauer, R.H., and J.M. Wunderle, Jr. 1992. The effect of Hurricane
Hugo on bird populations on St. Croix, U.S. Virgin Islands. Wilson
Bulletin 104:656–673.

Wunderle, J.M., Jr., D.J. Lodge, and R.B. Waide. 1992. Shortterm
effects of Hurricane Gilbert on terrestrial bird populations
on Jamaica. Auk 109:148–166.