|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.)
|© Asociación Ambiente Sur|
2012-2013 breeding season
- Very comprehensive surveys produced a tally of 691 adult hooded grebes.
- The use of guardians at breeding sites greatly increased reproductive success by controlling predators.
- Mink predation is a top concern; important lessons were learned and information on mink distribution is still being gathered and analyzed.
|Guardians at work. © Asociación Ambiente Sur|
- For the first time, a simultaneous count was performed in key areas of the breeding range, with four teams surveying the plateaus during January. This enabled an accurate census.
- 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.
- 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.
- Summary of survey results for September 2012 to May 2013:
- 290 lakes visited (exceeding the target of 200 lakes); ten with breeding hooded grebes
- 691 adult hooded grebes counted
- 275 nests built
- 144 surviving chicks (to juvenile plumage)
- number of lakes with trout: 71 (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).
- Dr. Laura Fasola, a mink expert, was enlisted to direct mink program activities. 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), the results from which are still being evaluated.
- 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.
- Several designs for windbreaks were tested; none was very successful in extreme wind conditions. But a new and very promising design was developed by an experienced engineer, and this design may prove effective.
- Collaborations: 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.
- 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.
- Trout have been introduced to dozens of lakes on the Strobel plateau, where hooded grebes have declined precipitously. On the highly important (to grebes) Buenos Aires plateau, trout have been found in two lakes. Intensive netting and other fishing activities conducted there this past field season produced only a single fish, indicating that trout populations are not yet established.
- Through an agreement with the Fish Service of Santa Cruz province, a regulation was passed that forbids the introduction of trout on the Buenos Aires plateau; the aim is to extend this regulation to other plateaus. The importance of refraining from releasing trout was explained to local residents.
- 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.
- The creation of Patagonia National Park was secured when a law transferring administration of the land from the province of Santa Cruz to the national authorities was passed on March 14, 2013.
- Educational activities continued at the Interpretive Centre in Río Gallegos. This included performances of a play that portrayed the various problems that hooded grebes face as well as issues concerning local wild spaces.
|At the Río Gallegos Interpretive Centre. © Asociación Ambiente Sur|
DiscussionThe results from the 2012-2013 breeding season are encouraging. Reproductive success was greatly increased from the preceding two years, with 144 young surviving. While this may seem low, in normal conditions free of human-related threats, hooded grebes have high adult survivorship and relatively low annual recruitment of young. The importance of controlling and eventually eliminating mink from hooded grebe breeding areas is now clear and this will be a key focus during the next few years. 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.
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