The Galápagos Archipelago is recognized internationally as a unique eco-region, and many of the species that inhabit these islands can be found nowhere else on Earth. The Ecuadorian government recognized the value of this ecosystem, and, beginning in 1959, they designated 97% of the Archipelago as Ecuador's first National Park. The Charles Darwin Foundation also was founded in 1959 and, since then, the Park Service and the Foundation have worked towards preserving the Galápagos' unique flora and fauna for future generations. The waved albatross (Phoebastria irrorata) is the largest bird species found in the Galápagos Archipelago and was recognized as an iconic species early in the Park's history; it is the only tropical albatross. This species spends the majority of its life foraging at sea and is an important predator in the Humboldt Current off of the coast of South America. With the exception of a few pairs, this albatross breeds entirely on the southeastern most island of the archipelago, Española. Tourists visit Española every year to watch the elaborate courtship dances of this species, and albatrosses in general have been the foci of legends among sailors for centuries.
M.P. Harris (1969) began banding waved albatross as early as 1961, marking the beginning of a long-term monitoring program with a focus on estimating age-specific first-time breeding, abundance, and survival. This initial effort resulted in the first estimates of abundance and survival for the waved albatross (Harris 1973). Following these initial estimates, the population size of the waved albatross has been estimated in 1994 (Douglas 1998), 2001 (Anderson et al. 2002), and 2007 (Anderson et al. 2008). These estimates suggest that the population has been declining since 1994. Motivated by this apparent decline, Awkerman et al. (2006) investigated survival and concluded that survival estimates from 1999-2005 were lower than average survival from 1961-1970 (Harris 1973). Today, the waved albatross is considered critically endangered, with bycatch in artisanal longline fisheries and the increased occurrence of El Niño-Southern Oscillation events thought to be contributing to these observed declines in survival and abundance. Given these observed declines in the waved albatross, the importance of the species in the ecosystem, and its intrinsic value in terms of biodiversity, continued monitoring and analysis efforts are needed to evaluate trends over time, and to gauge the effectiveness of management actions. My thesis is focused on these topics.
In Chapter 1:, I describe a framework to estimate abundance of wildlife populations, apply this framework to estimate population size of the waved albatross at a major breeding colony on Española Island, and I conclude by providing recommendations for future island-wide surveys of this species.
In Chapter 2:, I revisit the dataset collected by M.P. Harris and the Galápagos National Park from 1961-1981 as well as a more recent dataset collected by K.P. Huyvaert and colleagues. I analyzed these datasets in a multistate mark-recapture framework to estimate and compare estimates of adult survival as well as other important demographic parameters that have not yet been evaluated for this species.
Bycatch from fisheries and extreme weather events have influenced survival and breeding probabilities of many pelagic seabird species worldwide. Lower adult survival of the waved albatross is thought to be associated with bycatch in the small-scale fishery located off of the coasts of Peru and Ecuador as well as with El Niño-Southern Oscillation events. Previous efforts to document these threats have not formally considered that a variable proportion of the population does not breed every year or that different life history stages may have different survival rates.
The results from Chapter 1 suggest a continued decline in the principal breeding population of the waved albatross since 1994, and Chapter 2 shows indirect evidence that this decline may be linked to higher mortality associated with recent documented increases in small-scale longline fishing effort off of the coast of South America. Outside of the Galapagos Marine Reserve where fishing is heavily regulated by the Galapagos National Park Service, little is done to directly manage artisanal fishing operations off of the coasts of Peru and Ecuador. Conservation initiatives recognizing the environmental impact of fishing in this zone have been promoting reduction of seabird bycatch by educating local fishermen. Despite these conservation efforts, the results from my thesis suggest a continued population decline for this critically endangered species and additional mitigation may be needed for the persistence of the waved albatross.
|Advisor:||Doherty, Paul F., Huyvaert, Kathryn P.|
|School:||Colorado State University|
|Department:||Fish, Wildlife, and Conservation Biology|
|School Location:||United States -- Colorado|
|Source:||MAI 52/04M(E), Masters Abstracts International|
|Subjects:||Wildlife Conservation, Wildlife Management, Natural Resource Management|
|Keywords:||Abundance, Albatross, El Nino-Southern Oscillation, Longline, Recapture, Survival|
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