Wildlife from remote corners of the planet are suffering the impacts of human activities. These impacts were well known to the conservation community and in recent days even to people who are not “into” conservation. Among the sad stories is the one of the Hooded Grebe, although this is not a fully sad tale as hope is still a part of it.
The Hooded Grebe is a handsome medium-sized grebe (about 1 pound/0.5 kilograms) that inhabits one of the most remote areas in the even more remote Austral Patagonia. It inhabits crystal clear, shallow lakes, in nine highland plateaus close to the Andes in Santa Cruz province Argentina, and some of the lakes in nearby Chile. The remoteness of the area was the cause of the “late” discovery of the species for the occidental science. In 1974 Mauricio Rumboll and Eduardo Shaw found a group of the grebes in a small, shallow lake of the Vizcachas plateau, near the now famous city of El Calafate (nearby the Perito Moreno Glacier). The discovery of such a good-looking grebe was world news (within the small group of people that could become interested on such an event). Because of this, many specialists arrived to the area and a whole project was launched by the Fundación Vida Silvestre Argentina with the support of international institutions. The grebe was studied for more than a decade and eventually it turns out that the population looks healthy, and was even said that the remoteness of the habitat was enough protection to counteract potential human impacts; meaning that isolation was the best tool for “conservation”. But by mid 2000’s some shadows began appearing over the Hooded Grebe.
In 2008-2009 a group of naturalists from the NGOs Aves Argentinas and the local Ambiente Sur went to the plateaus to check on important areas for the grebes. This alarm was turned on by birdwatcher guides, claiming that the grebe was becoming harder to find every year, even in the “classical” spots. The first campaign was horrible! In lakes where in the 1980’s the grebes were counted in several hundreds, or even thousands, there were only dozens. During that summer, the numbers only reached to 200 individuals. Therefore, the two NGOs decided to launch the “new” Hooded Grebe Project. To accomplish their first campaign, they called for the support of biologists, park rangers, field technicians and hundreds of volunteers. Since the summer of 2010, surveys had been conducted, where the numbers plummeted from over 5,000 individuals during the 1980’s to less than 800 mature individuals.
The history of how that crisis began was unraveled with many hours of observation, the monitoring of grebe colonies, interviews with local stakeholders and time-consuming data analysis. The reasons of the population crisis are a synergy between global climate change and invasive species – the ‘usual’ set of threats. The global climate change had been reducing the reproductive area of the Hooded Grebe, due to a combination of an increase of temperature, a reduction of the snowfall during winter and an increase of the wind gust (that destroys the colonies, but also helps to dry the lakes by blowing the water away). This has little to do with global climate change effects, but a lot to do with invasive species and with some other strategies to counteract the effects of the population reduction.
The strategies that were set up were focused to maximize the recruitment of new individuals per year. The revolutionary concept of the ‘colony guardians’ was born; field technicians and volunteers spent the whole breeding cycle living on the lakes where the best colonies (i.e. colonies with more than 10 pairs) were located. To support the colony guardians program the Hooded Grebe Project needed to secure a fully trained group of field technicians, with extreme-weather camping equipment, full quality field equipment (for data sampling) and extremely strong vehicles to reach those remote sites. The result was that the colony guardian actions duplicated the breeding success of the Hooded Grebe, from 0.3 chicks per pair to 0.6 chicks per pair per season. Superb and vital results helped the survival of this wonderful species. But this was a local and acute method. Something was needed to help the colony guardians, especially for those small colonies that there were little chances to protect.
Therefore a control of invasive species was developed, focusing principally on the most serious threat – the invasive American Mink. This carnivorous species was released in Patagonia during the first half of the 20th century. It lives associated to streams, rivers and lakes, thus it is a typical predator of waterfowl. The Hooded Grebe has no other mammalian predator, since its only natural predators are birds of prey such as the Peregrine Falcon. The Hooded Grebe has no strategies to avoid the mink, and even more, it seems that they do not even consider the mink a threat until it is too late. There have been at least three surplus killings detected. The most shocking one was when a young male mink killed over 30 grebes in a single night. In consequence there is no room for the minks in the highlands plateaus. The control program set up in the rivers around the Buenos Aires Lake Plateau, where the Patagonia National Park is located, had fantastic results. Since it began in 2013 there were no cases of minks killing any Hooded Grebes, and the mink population has dropped all around the plateau. Another good news for the grebes.
With the other two invasive species the situation is completely different. On the one hand, there is the Rainbow Trout, where their presence in the Hooded Grebe’s lakes produce changes in the water conditions, affecting the whole plant and invertebrate community those lakes are completely life-less. This is what is known as ‘trophic cascades’. Rainbow trout is a huge income for ranch owners, mostly due to the fly-fishing industry. However, the more remote lakes are not good since it is virtually impossible for fisherman to reach those areas. Removing the stoked trout from those lakes will probably restore the original conditions of the lakes. The third invasive species, the Kelp Gull, is native from Patagonia, although it has reached the highland lakes by following human settlements. The gulls predate over nests and small grebe chicks. A single gull is able to destroy a whole colony of over 30 nests in 45 minutes. The strategy for the gull is the same as colony guardian, but also, by reducing reproduction rates in gull’s colonies by interrupting egg development.
Lastly the most ambitious strategy is to learn how to raise chicks from abandoned eggs or eggs that had been washed out from the lakes by the windstorms. Hooded Grebe is one (or the only one) of the grebe family with the lowest natural breeding rate success. Ninety seven percent of the pairs raise only one chick, after laying two eggs. The extra egg is abandoned as soon as the first chick hatches. Learning how to raise a grebe chick is a great challenge, since there was only one previous experience. So far it was not possible to raise Hooded Grebe chicks, but successful experiences have being gained with Silvery Grebes from the same lakes.
All the efforts had served to stop population decline. The counts from the past five years look promising, where the number are stable and even a small incline has shown in the past three years. This slow climb up of about 1% per year is a light in the horizon for the Hooded Grebe conservation. However much more needs to be done. The threats are still present, not only as global climate change, but also the synergy with the invasive species that are still spreading. A multi-institutional work is necessary, with a right mix between NGOs, scientific institutions and the decision makers of provincial and national levels. The need for urgent actions are fundamental, even more so when national governments are currently building two huge hydroelectric dams that will affect the estuary of the Santa Cruz River. That estuary holds 98% of the wintering population, and unfortunately the greed for energy will jeopardize the future of the Hooded Grebe.
