Monitoring Avian Health in the Galapagos Islands: Developing an “Early Warning System”
Introduced diseases may present significant risks to naïve avian populations. Recognizing that factor, a cooperative program is being developed to monitor avian health in the Galapagos Islands. The program has two basic components: 1) an ongoing monitoring program that in its first year examined samples from Galapagos hawks (Buteo galapagoensis), waved albatrosses (Phoebastria irrorata), domestic chickens (Gallus gallus), and rock doves (Columba livia), and 2) an organized effort to transfer information and technology to Ecuadorian personnel. The latter effort includes stationing a board-certified veterinary pathologist at the Charles Darwin Research Station to train Ecuadorian veterinary scientists in pathology techniques, and to provide more in-depth monitoring of avian species. The program is a unique collaborative effort between the Des Lee Professor of Zoological Studies at the University of Missouri-St. Louis, the Charles Darwin Research Station, the Galapagos National Park, the Saint Louis Zoo, and the Hawaii Field Station of the National Wildlife Health Center.
Island populations are uniquely susceptible to many risks, including the threat of introduced diseases. A clear example of this is Hawaii—a state that accounts for 0.2% of the USA’s landmass, but over 50% of its extinctions. Hawaiian avifauna has been devastated by a combination of introduced predators, diseases and habitat alteration. Of the 88 species present when the Polynesians first arrived, only 28 remain. Today, avian malaria has a major, negative impact on many species of birds, limiting some avian species to habitats above the range of the mosquito intermediate host. In contrast, the unique avian fauna of the Galapagos Islands, well known after Charles Darwin’s voyages and subsequent studies, remains relatively intact. To date, no avian species native to the Galapagos has gone extinct, although several are severely threatened. Several avian diseases that can have a notable, negative impact on wild populations, including avian malaria, have not yet been reported in the Galapagos (however, the Culex mosquito vector has been recorded). Our survey has confirmed the presence of avian pox on human-inhabited islands in both domestic and endemic bird species. In addition, the risk of introduced diseases is increasing with increased travel and commerce between the archipelago and the mainland. Recognizing this fact, personnel from the Charles Darwin Research Station (CDRS), the Galapagos National Park (GNP), and the Hawaii Field Station of the National Wildlife Health Center (HFSNWHC) organized a meeting at Princeton University in 2000 to address ways to monitor avian health and to support preventive measures to maintain it. At the same time, the Saint Louis Zoo (SLZ) and the Des Lee Professor at University of Missouri-St. Louis (UMSL) were discussing potential joint efforts in the Galapagos, and again, identified avian health monitoring as a goal. A joint program resulted when this example of “convergent evolution” was recognized.
Program Design and Development
The avian health monitoring program was designed in a deliberate, step-wise fashion. The first year featured a workshop on avian diseases held at the CDRS in Puerto Ayora on Santa Cruz Island. Participants included agricultural veterinarians, biologists, CDRS personnel, and game guards. The classroom work provided an overview of avian diseases of concern, and avian anatomy. The latter preceded a practical workshop on how to collect blood from living birds, and how to perform a post-mortem examination and collect tissues from dead birds. The goal was to create a team that could collect samples both from organized studies and from opportunistic necropsy cases (e.g., such as a game guard might come across in the field). With funds provided by UMSL’s Des Lee Professor in Zoological Studies, the CDRS hired an Ecuadorian veterinary scientist to coordinate ongoing work in the Galapagos. Also, during the first year, necropsy manuals from the HFSNWHC were translated into Spanish and into an electronic format to facilitate distribution.
The applied techniques laboratory used both domestic chickens purchased from a variety of local farms and rock doves that were trapped as part of an eradication program. Each bird received a physical examination, followed by blood collection and a cloacal swab. Then the birds were humanely euthanatized and a post-mortem examination was performed by course participants. Therefore, these birds provided not only an applied experience, but also provided disease information from domestic and introduced species. Also, as part of the monitoring program, blood samples and cloacal swabs were collected by UMSL graduate students during the course of their studies of Galapagos hawks and waved albatrosses. After the workshop, additional albatross and hawk samples were collected on Espanola Island, and chickens and pigeons were sampled and necropsied on San Cristobal Island (see Table 1 for diseases evaluated). In a related study, an intensive effort was made to quantify and correlate ectoparasite loads in Galapagos hawks with their health status.
Table 1. Examinations and tests performed
- Physical examination
- Complete blood count (CBC)
- Serum chemistry panel
- Cloacal swab for enteric pathogens (Salmonella, Shigella, Campylobacter sp.)
- Chlamydial testing
- Avian cholera
- Avian influenza
- Newcastle disease
- Paramyxovirus 2 and 3
- Infectious bronchitis
- Avian adenovirus
- Avian encephalomyelitis virus
- Avian reovirus
- Marek’s disease
- Infectious bursal disease
- Necropsies (including histopathology) on domestic chickens and eradicated pigeons
The wild species studied were selected for several reasons. Dr. Parker’s graduate students had access to these species due to ongoing studies on the hawks and albatrosses. Both species are also sufficiently large-bodied to collect adequate blood samples for multiple tests warranted in an initial surveillance project. These species also presented an interesting contrast: the Galapagos hawk populations on each island are isolated, so they should represent the top of the food chain for each locale, whereas, the far-ranging pelagic habits of the waved albatrosses should represent the health of the surrounding ocean. Additionally, we will make comparisons in patterns of disease transmission between monogamous and polyandrous hawk populations. Obviously, the domestic chickens and introduced rock doves serve two important roles: 1) in the chickens, we are monitoring diseases in a domesticated species often imported from the mainland, and 2) in the rock doves, we are evaluating a potential “sentinel” species for diseases in the wild due to the ability to necropsy them, and provide a more definitive source of diagnostic information.
It was recognized that this was an initial step, and that further development of the program would depend on an ongoing commitment. To that end, in March 2002, a planning meeting among all major participants was held in St. Louis to determine the next stage of the project. As a result, another workshop will be held in July 2002 at CDRS that will feature more advanced training, and additional experience in sample collection. Also, starting in July 2002, a commitment was made to place a board-certified veterinary pathologist at the CDRS for 1 yr. The pathologist’s purpose is two-fold: 1) to assist in the collection, and processing and evaluation of post-mortem tissues from additional avian species (the source of which includes rock dove eradication program, road kills from the inhabited islands, and opportunistically found birds), and more importantly, 2) working with the CDRS Ecuadorian veterinary scientist to develop “in-country” pathology expertise. An additional benefit is to have their expertise present in case of an unexpected medical event, such as happened in 2001 with a sudden die-off of 19 white-cheeked pintail ducks (Anas bahamensis galapagoensis) on Isabela Island.
The program’s expenses have included travel, equipment, materials, sample collection, meeting costs, and salaries of personnel. The Des Lee Chair of Zoological Studies at UMSL has supported travel, the salary of the Ecuadorian veterinary scientist to date, supplies and sample processing in addition to a donation of significant amounts of equipment (microscope, liquid nitrogen shippers and storage tanks). The Saint Louis Zoo supported the participation of its staff members, and the salary for the first year of the pathology position. The Charles Darwin Research Station is providing ornithology and local veterinary personnel, logistic support for the study, and laboratory space for the pathologist. The Galapagos National Park has provided assistance (and when appropriate, permits) for sample collection. The Hawaii Field Station of the National Wildlife Health Center has provided personnel and Spanish necropsy manuals. It is anticipated that these sources of funding and support will be ongoing. Additionally, these initial investments are designed to build a strong infrastructure that will support grant applications for the individual research projects associated with this program.
Additional sampling in future surveys will include heavy metals and pesticides whenever possible. PCR techniques for avian malaria will be added to the diagnostic regimen. Pox viral lesions are currently being cultured at the Laboratory of Dr. Tripathy at the University of Illinois in order to determine the relationship (if any) between the lesions on the chickens, doves, and finches. With the addition of a graduate student in biology who will study Galapagos doves (Zenaida galapagoensis), the project will expand to another species. Since introduced rock doves are not found on all islands inhabited by Galapagos doves, this species offers an opportunity to make comparisons between disease prevalence in native doves on islands with and without the introduced rock doves (e.g., Trichomonas sp. infections). The ongoing nature of the program, and also potentially, reference collections, will provide opportunities for comparisons of changes in health issues over time. It is anticipated that in addition to the broad areas of study described above, the veterinary pathologist and the CDRS veterinary scientist will also identify more focused areas of concern (e.g., specific disease issues).
Another important feature will be establishing firmer criteria for overall disease monitoring priorities, and adapting and modifying the monitoring program’s activities based on each year’s findings. Obviously, new diseases will also be considered (e.g., West Nile Virus). A significant challenge is implementing the program’s findings in a manner that leads to practical recommendations that prevent the spread of disease. For example, scientific evidence may suggest alterations be made in the existing quarantine regulations. Finally, as the collaboration grows, further training of park and research personnel will take place.
The Saint Louis Zoo, the Des Lee Professor of Zoological Studies at UMSL, the Charles Darwin Research Station, the Galapagos National Parks, and the Hawaii Field Station of the National Wildlife Health Center have formed a unique collaborative (that includes a zoo, an endowed university chair, a non-profit conservation organization, and Ecuadorian and United States governmental agencies) to address the threat of introduced disease to the Galapagos’ avifauna. To achieve this goal, the program has made use of the resources and expertise of each of its partners. As the program grows, it is anticipated that the pathologist, and the local veterinarians and biologists will identify additional projects in areas of concern. We believe that having full-time personnel focused on these issues is critical to the project’s organization, to the development of local expertise, and subsequently, to the collection of valuable surveillance data. These are all critical factors in developing a long-term monitoring program to prevent the introduction of disease. In that light, the program may be viewed as an “early warning system” for the avifauna of this unique ecosystem.