Eleven Recommended Management Actions for Recovery and Their Rationale
After careful review of the findings about the aga and the brown tree snake and consideration of the recovery options for the aga in the context of other endangered species programs, including those for corvids, the committee offers 11 recommendations for activities to take place in the next 3 years. The first 6 recommendations involve management and research; the remaining 5 involve infrastructure and support. Table 6-1 summarizes the proposed schedule. The committee does not recommend the continued maintenance of a captive breeding population or the transfer of crows from Rota to Guam during this period. The latter option should be considered only after studies indicate that translocation will not jeopardize the Rota population and that snake-control measures on Guam are sufficient to predict higher than current levels of survivorship of aga on Guam. Given the fact that two aga populations are extant at present, the committee strongly recommends that comparative, experimental studies be conducted.
Expand and increase research, development, and implementation of methods to control the brown tree snake and to prevent its spread to other islands. The agencies most in need of allocating additional funding are the US Department of the Interior (DOI) National Biological Service (NBS), the Department of Defense (DOD), the Guam Department of Agriculture Division of Aquatic and Wildlife Resources (DAWR), and the Commonwealth of the Northern Mariana Islands (CNMI) Department of Lands and Natural Resources Division of Fish and Wildlife (DFW). Recovery of the Guam aga population will not be possible unless the
effects of the brown tree snake can be mitigated. Furthermore, the most serious threat to the aga as a species is the spread of the brown tree snake to the island of Rota. The committee strongly recommends that a comprehensive approach to snake control be undertaken. It should include the following actions:
Institute aggressive interdiction measures for snakes on Guam, such as exclosures in and around air and naval ports, to protect cargo going to Rota. The current US Department of Agriculture (USDA) Animal Damage Control (ADC) program is insufficient for this task. Have scientists and managers outside the agency conduct a critical review of the current ADC program as soon as possible. See chapter 3, "Efforts to Control the Snake."
Conduct early detection and eradication programs for brown tree snakes on other islands, including Rota. Protect ports on other islands with cargo quarantine enclosures, fumigation, and inspection of high-risk cargo. If snakes are discovered in port or cargo-storage areas, deploy barriers to slow their dispersal from the initial sites of infestation. Ascertain the extent of infestation (density and area occupied) and conduct intensive eradication effort. See chapter 3, "Threat of Spread of the Brown Tree Snake to Other Islands."
Establish a detector dog and handler program within the CNMI (especially Rota) to facilitate interdiction of snakes in high-risk cargo and other equipment that is not readily amenable to visual inspection. Test the effectiveness of the dog and handler teams. Use artificial training aids to solve problems related to training and maintenance of the dogs on islands where snakes are not available for training purposes. See chapter 3, "Efforts to Control" and "Threat of Spread of the Brown Tree Snake to Other Islands.''
Continue and expand research to improve brown tree snake control methods. Train all personnel involved in control efforts. See chapter 3, "Threat of Spread of the Brown Tree Snake to Other Islands" and "Prognosis for Control on Guam."
Study the behavior, population biology, and health of marked birds on both Guam and Rota. Identify limiting factors and collect data to elucidate the demography of each population. Make comparisons between the two populations with regard to fecundity, the causes and timing of adult and juvenile deaths, changes in home-range sizes, habitat use, foraging and roosting behavior, and, on Guam, responses to the presence and absence of brown tree snakes. This project will involve the following tasks.
Equip a subset of captured birds with radiotransmitters so that both diurnal and nocturnal monitoring can be conducted. See "Possible Causes of Population Declines," "Past and Current Conservation Management" in chapter 2, and ''Monitoring of Released Birds" in chapter 5.
At the time of banding, conduct complete physical examinations and health screens and collect samples of blood for genetic analyses. Using this information, obtain baseline data on the genetic variation in the populations, the prevalence of diseases and parasites, and normal hematology and clinical-chemistry values. See "Possible Causes of Population Declines" and "Past and Current Conservation Management" in chapter 2.
Release all captive female aga and 3 of the captive males from the Mariana Rescue and Survey (MARS) program on Guam before the 1996–1997 breeding season. Pairs that formed strong pairbonds in captivity should be released together. Release unpaired females in territories occupied by suspected unpaired males. Release the captive birds from snakeproof aviaries equipped with funnel and noose traps built into them. Wild aga lured into the aviary should be captured and banded. Release the remaining 2 captive MARS males before the 1997–1998 breeding season. Release the 2 captive-reared juvenile aga now held on Guam before the 1996–1997 breeding season. Conduct thorough health screening of the captive birds before releasing them to the wild. All released birds should be radio-tagged and their behavior and interactions with snakes monitored closely day and night. See "Monitoring of Released Birds" and "Translocation from Captivity to Guam, Rota, or Other Islands" in chapter 5.
Place electric barriers on all nest trees to protect nests from brown tree snakes and monitor lizards, and increase trapping efforts in nest trees and adjacent areas. Test the effectiveness of nest-tree barriers, exclosure barriers, and trapping of brown tree snakes in increasing the rate of construction of nests and the production of viable eggs by aga. To do so, place tree barriers, exclosures, and traps for brown tree snakes in aga territories. See "Prognosis for Control on Guam" in chapter 3.
Collect all wild aga eggs after several days of incubation for intensive avicultural management. Allow some natural incubation of eggs by the female. Raise hatchlings in captivity, releasing them as juveniles on the fringes of occupied crow habitat before the next breeding season. See "Natural History" in
Assess the feasibility of translocating birds to islands other than Guam or Rota, including islands outside the Mariana archipelago. The committee favors preservation of the Guam and Rota populations over establishment of a population elsewhere. However, if the Guam population cannot be recovered, establish a second population on another island. If the recommendations outlined in this report are followed, data should be available within the next 3 years to determine whether translocation to islands outside the aga's historic range are warranted and desirable. However, before translocation to another island is considered, the following actions should be taken.
Complete a survey of the flora and fauna of the island, with emphasis on endemic species. See "Translocation from Guam, Rota, or Both to Other Islands" in chapter 5.
Assess the likelihood of establishing a self-sustaining population of crows on the island. See "Translocation from Guam, Rota, or Both to Other Islands" in chapter 5.
Evaluate the potential negative impact of the crows on the existing flora and fauna, particularly with regard to endemic species. See "Translocation from Guam, Rota, or Both to Other Islands" in chapter 5.
Assess the feasibility of eradicating nonnative species that might adversely effect aga. See "Translocation from Guam, Rota, or Both to Other Islands'' in chapter 5.
Consider the legal status of the crow on the receiving island. See "Translocation from Guam, Rota, or Both to Other Islands" in chapter 5.
Conduct surveys to determine whether brown tree snakes are on the receiving island. See "Translocation from Guam, Rota, or Both to Other Islands" in chapter 5.
Conduct annual censuses of the aga population on both islands about a month before the breeding season. Conduct a complete census of the population and map all territories. Teams of observers should coordinate their efforts to count crows simultaneously in subregions (drainages) of the island. Appraise the feasibility of an annual census on Rota. If such a census would detract from obtaining estimates of productivity and survivorship, a random sample of territories could be monitored annually. Playbacks of recorded aga vocalizations might be useful
Conduct complete postmortem examinations on all recoverable eggs and birds. A veterinary pathologist (preferably certified by the American College of Veterinary Pathologists) with experience in avian pathology should be enlisted for histopathologic examinations. From postmortem investigations, obtain accurate determinations of causes of death and information on endemic infections, parasitism, subclinical diseases, and nutritional condition. In addition, develop a tissue archive that can aid in future multidisciplinary research endeavors. See "Disease" in chapter 2.
As soon as possible, develop and implement a habitat conservation plan for Rota that preserves essential crow habitat but allows economic development in an ecologically responsible manner. See "Past and Current Conservation Management: Rota" in chapter 2.
Establish a professional-level research-manager position on Guam within the NBS. The position should be filled only after a wide search for an appropriate research scientist. The person should be capable of leading a rigorous research and management program for the aga and constructing a database of information on it and other endangered birds in the Mariana archipelago. See "Past and Current Conservation and Management" in chapter 2 and "Finding 11" in chapter 4. Responsibilities for the research leader include the following.
Ensuring effective communication among all recovery participants—DFW, DAWR, the DOI FWS and NBS, the USDA ADC program, DoD, conservation groups, and private individuals. Data should be kept in a centralized database and disseminated to all parties. The most effective and most efficient means of communication should be used, including e-mail, fax, electronic-database networks, and telephone conference calls.
Ensuring that recovery efforts for the aga are integrated and coordinated with other efforts to manage and conserve the flora and fauna of the Mariana Islands.
Within the next year, appoint a recovery team specifically for the aga. The recovery team should include a crow biologist, an 'alala specialist, a population biologist, an avian veterinarian, a snake biologist, and an animal-damage control specialist. If possible, members should represent all agencies and organizations with vested interests. The recommendations contained in this report are designed primarily to guide the recovery effort only for the next 3 years. A recovery plan should then be developed on the basis of an evaluation of the outcome of the recommended actions. To that end, the recovery team should receive tabulated data and regular reports from the field. The team should meet regularly, monitor progress of recovery actions, and identify research and management priorities. The new program must include all stakeholders, and it must facilitate transfer of information among them. Establishment of a recovery team for the aga would facilitate cooperation among agencies and individuals involved in the recovery effort. It should include regular participation by off-island experts, and receive and respond to periodic review by experts not associated with the program. The team must be responsive to new developments and not get bogged down in writing a long, comprehensive recovery plan that will be useful for guiding efforts for only a very short time. Recovery efforts for the aga need to be coordinated with recovery efforts aimed at other species, but crow recovery is best served by a single-species team. The FWS Pacific Island Recovery Team is responsible for the recovery of a variety of endangered and threatened species in the Pacific Basin. It cannot possibly provide the management and research focus that the aga deserves. See "Past and Current Conservation and Management" in chapter 2 and "Finding 11" in chapter 4.
Conduct a public education program that specifically addresses issues relevant to aga conservation, including the problems associated with the spread of the brown tree snake. All of Micronesia and Hawaii should be targeted for education about the brown tree snake. See "Past and Current Conservation and Management" in chapter 2. The education program should
Clearly define the problem, which might be different for different groups and different islands.
Identify and specifically target all appropriate constituencies (such as schoolchildren, farmers, hunters, developers, policy-makers, and church and community groups) with appropriate methods.
Focus feelings of national pride on indigenous wildlife, including the aga.
Involve local and indigenous people in implementing the program.
Incorporate materials previously produced by DAWR, FWS NBS, and ADC. These materials should be evaluated, expanded, and regularly updated to form a comprehensive educational program.
Develop systems for monitoring, evaluating, and revising the program. Programmatic evaluations should be based on both internal review by staff and input from external target audiences and participants.