|Project:||Preventing Extinction of the Hooded Grebe|
In more depth...
Project Partners and PersonnelOur partner is the Argentinian conservation organization Asociación Ambiente Sur, with project leader Santiago Imberti. Ambiente Sur works together on hooded grebe conservation and research with Aves Argentinas (project leader Hernán Casañas).
BackgroundThe Hooded Grebe, Podiceps gallardoi, is endemic to Santa Cruz province in southern Argentina. Its breeding range is restricted to upland plateaus (above 700 m asl) in which basaltic lagoons, where the grebes breed, are interspersed with grasslands and sheltered areas with shrubs. During the austral winter (the non-breeding season) the grebe migrates to the Atlantic coast to winters in river estuaries, areas that are also important for wintering shorebirds, both Patagonian and Neartic.
Now listed as Critically Endangered, the species has declined from a population estimated at 3000-5000 in the mid-1980s to one "unlikely to exceed 800". The good news is that the chief causes of its decline have been identified and can be addressed. Ambiente Sur (our partner) and Aves Argentinas have a comprehensive plan to do so. They have already been successful in reducing drowning in fishing nets at coastal wintering areas by shifting fishing activities away from areas used by the grebes.
Following years of promotion by Argentinean conservation organizations (Ambiente Sur, Aves Argentinas and Fundación Flora y Fauna Argentina), a new national park — Parque Nacional Patagonia — was created in March 2013. This will protect a sizeable portion of the breeding range of the hooded grebe, and the aim is to futher expand the park to include more if its breeding range.
PurposeTo prevent extinction of the hooded grebe and reverse its population decline by addressing human-related factors that limit breeding success and cause excess mortality.
- At breeding areas:
- Conduct surveys to estimate breeding population and locate colonies; train volunteers; assign a guardian to each active colony.
- Trap American mink and collect information on their numbers and distribution.
- Design and implement wind-breaks to prevent loss of nests from wind storms and waves.
- Take measures to reduce predation of hooded grebes by kelp gulls.
- Continue to pursue expansion of the newly created Patagonia National Park.
- Funded separately:
Remove trout completely from lakes (using a team of artisanal fisherman) and prevent introduction
of trout to new areas.
At wintering areas:
- Survey and monitor wintering sites (Atlantic coastal estuaries);
- Produce displays on the hooded grebe for Ambiente Sur's interpretive centre at Río Gallegos;
- Continue theatre production on the hooded grebe and other Patagonian conservation issues for
students visiting the interpretive centre.
Future measures (not part of this project):
- Acquire private lands to be managed by Ambiente Sur as a reserve to supplement the new national park, Parque Nacional Patagonia, and protect sufficient breeding habitat to secure the species' recovery and future. (The market price for land in the area is ~$40-70/ha.)
|© Diego Punta Fernandez||© Diego Punta Fernandez|
Parque Nacional PatagoniaIn March 2013 Argentina declared a new national park — Parque Nacional Patagonia — support for which was leveraged by this project. This represents a major breakthrough for the grebe and the region, protecting 52,000 hectares and one of the most important grebe breeding colonies.
2012-2013 breeding season
- Mink predation is a top concern. The use of guardians deterred some mink predation in 2012-2013 and in the 2013-2014 breeding season, a comprehensive mink control program (that took advantage of findins from field research done by an independent researcher) totally eliminated mink predation, leading to sharply higher reproducive success.
- Very comprehensive surveys in 2012-2013 produced a tally of 691 adult hooded grebes.
|Guardians at work. © Asociación Ambiente Sur|
Survey and Guardianship of Breeding SitesVery comprehensive surveys were carried out in the breeding season of September 2012 to May 2013. All the plateaus that have ever held hooded grebes were covered and almost all the lakes with any hooded grebe records were visited (see Figures A and B) - the most thorough census ever. For the first time, a simultaneous count was performed in key areas of the breeding range, with four teams surveying the plateaus during January, enabling an accurate census since the same individual grebes could not be double counted at different sites. In summary:
- 290 lakes visited (exceeding the target of 200 lakes); ten with breeding hooded grebes
- a tally of 691 adult hooded grebes counted
- 275 nests built
- 144 surviving chicks (to juvenile plumage)
- 71 lakes with trout(none of which had nesting hooded grebes)
Figure A: Numbers indicate the most important plateaus in Santa Cruz province where hooded grebes breed. Letters indicate wintering sites. 1. Buenos Aires, 2. Asador, 3. Strobel, 4. Ventana, 5. Moro, 6. Siberia, 7. Viedma, 8. La Gringa, 9. Vizcachas, & 10. La Torre.
A. Gallegos estuary, B. Coyle estuary, C. Santa Cruz & Chico rivers, & D. San Julián Bay.
Figure B: Lakes visited during breeding seasons 1984-1985 (black) & 2012-2013 (white).
Many of the lakes with grebes received several visits over the season and those with breeding colonies were attended by guardians who camped by the lake throughout the grebe's breeding season. Guardians took measures to keep gulls and mink from grebe colonies and they monitored grebe breeding activity through nest building, laying, incubation and development of young. The use of guardians at breeding sites is the single most important action for improving reproductive success of the grebe.
To address wind damage to nests, several designs for windbreaks were tested; none was very successful in extreme wind conditions. However, a new and very promising design was developed by an experienced engineer, and this design may prove effective.
Addressing PredationMink predation is a top concern. Dr. Laura Fasola, an Argentinean mink expert (not funded by ICFC) led an investigation of the population dynamics of the introduced American mink. She trained guardians and volunteers in tracking and trapping mink and led efforts to determine the species' distribution on and between the plateaus. This work involved surveys and "camera trapping" (cameras with motion detectors). At two very important breeding sites alarming incidents of mink predation on grebes occurred. At El Cervecero, Buenos Aires plateau, a lone mink killed 15 adults and 7 juveniles. At La Siberia plateau, mink killed ten adults and 5 chicks. These incidents occurred late in breeding season when it was thought the grebes were safe from mink. This points to the need to extend mink control activities to the period when the young have left the nest. In total close to 50 mink predations occurred, but the trapping of five mink prevented many more.
The results of this study informed an intricate plan to reduce mink reproduction and to eradicate mink from the watercourses and high plateau grebe breeding colonies. As this plan is implemented in the 2013-2014 breeding season we are seeing improved success compared to past mink control efforts. Another concern is trout, which have been introduced to dozens of lakes on the Strobel plateau, where hooded grebes have declined precipitously. Limnology work revealed that the presence of trout:
- adversely alters the composition and number of aquatic invertebrates on which the hooded grebe feeds;
- reduces light penetration, which leads to an increase in undesirable algae; and
- increases phytoplanton density, which impairs the growth of the aquatic plant hooded grebes use for making nesting platforms.
- Also, large trout likely prey on hooded grebes.
Where kelp gulls were present near hooded grebe colonies, guardians scared them off using recordings of gull distress calls. Measures to render eggs infertile were undertaken at one gull colony. Physical deterrents to nesting will also be employed at gull nestng sites. No predations by kelp gulls were observed.
EducationPublic outreach and education efforts in Río Gallegos have been pivotal in developing local awareness of the hooded grebe and its plight. A 3-dimensional dynamic display in the local interpretive centre depicts the grebe habitat and threats. Volunteer training and the employment of young local conservationists is increasing conservation skills in this remote and harsh environment. Activities also include performances of a play portraying the various problems that hooded grebes face as well as issues concerning local wild spaces.
|At the Río Gallegos Interpretive Centre. © Asociación Ambiente Sur|
CollaborationsThe research informing this project would not be possible without a number of local collaborations, which we gratefully acknowledge: researchers from Centro Austral de Investigaciones Científicas worked on the American mink component; Centro Nacional Patagónico, Universidad Nacional de Buenos Aires did limnological (freshwater) work; and the Administración de Parques Nacionales assisted in limnological work and is working to develop the newly created Patagonia National Park.
The futureThe population benefits from mink control efforts is extremely encouraging. Other work will continue to reduce threats from trout, kelp gulls, severe wind storms and grazing. (Improved waste treatment is one of the measures expected to reduce numbers of kelp gulls.)
Increased attention is being given to the plight of the hooded grebe and efforts to save it. Over 100,000 people have watched a 45-minute documentary on the hooded grebe. The new national park is a huge step forward in conserving the hooded grebe. And the two Argentinean conservation organizations who, with Fundación Flora y Fauna Argentina, made that park a reality will continue to do their utmost to secure the future of this enchanting bird. ICFC looks forward to continuing to partner with Asociación Ambiente Sur in this effort.