Every autumn within the Southern Hemisphere, Magellanic penguins go away their coastal nesting websites in South America. For adults, their summer time activity — breeding, or a minimum of looking to — is whole. Newly fledged chicks and adults regularly head out to sea to spend the wintry weather feeding. They received’t go back to land till spring.
Yet lifestyles for those birds after they wintry weather offshore is in large part a thriller to the scientists who find out about Magellanic penguins — and who recommend for his or her conservation amid declining inhabitants numbers.
“The winter period is something of a black box for us in terms of understanding Magellanic penguins,” mentioned Ginger Rebstock, a University of Washington analysis scientist. “We know the least amount about this part of their year.”
But analysis by way of Rebstock and P. Dee Boersma, a UW professor of biology and founding father of the Center for Ecosystem Sentinels, is beginning to pry open that black field and uncover how Magellanic penguins from one nesting website, Punta Tombo in Argentina, fare all the way through the wintry weather months. In a paper printed Aug. nine within the magazine Marine Ecology Progress Series, they record that the Río de l. a. Plata — which drains South America’s second-largest river gadget after the Amazon — strongly influences oceanographic prerequisites within the Magellanic penguins’ wintry weather feeding waters. Those oceanographic options, they record, display up within the body prerequisites of Magellanic penguin women folk, however no longer men, when the penguins go back to their nesting grounds in spring.
“Researchers only get to study the penguins up close — monitor their biology, their health, their population numbers — for the one time in the year that they come to nesting sites like Punta Tombo to breed,” mentioned Rebstock. “Until now, we have not really known how conditions out in the ocean, where they spend the entire winter, affect them.”
Magellanic penguins are believed to swim masses of miles in wintry weather to feed on fish such as anchovy and sardines. For penguins originating at Punta Tombo, this could imply swimming greater than 1,000 miles north alongside the coast as much as southern Brazil. They normally keep alongside the continental shelf in waters most often not more than about 650 toes deep.
To perceive the oceanographic dynamics on this area, Rebstock became her consideration to area. She analyzed 30 years of weekly sea-surface temperature information, which National Oceanic and Atmospheric Administration satellites accrued for the ones South American coastal waters from 1982 to 2012. Data display that geographic options of coastal South America are accountable for key permutations in ocean prerequisites.
For instance, her research printed that the Río de l. a. Plata, which enters the sea between Argentina and Uruguay, is the main driving force of oceanographic prerequisites within the penguins’ wintry weather feeding waters. The river discharges silt, microbes and vitamins into the sea as a plume, which disperses in numerous instructions in line with prevailing winds. Strong winds from the southwest, for instance, can unfold the plume north alongside masses of miles of Brazilian beach. If winds are weaker, the plume remains close to the mouth of the Río de l. a. Plata.
Rebstock then analyzed whether or not permutations in those oceanographic options — such as a robust, dispersed plume or a susceptible, localized plume — had been related to the body situation of penguins on the time in their arrival at Punta Tombo. Boersma and her team have accrued knowledge at the health and state of particular person penguins after they arrive Punta Tombo for greater than 3 a long time. According to their information, the body prerequisites of male Magellanic penguins weren’t correlated with the level of the plume. But Rebstock discovered that feminine penguins arrived again at Punta Tombo previous, and in fitter body situation, if the Río de l. a. Plata plume was once weaker in wintry weather. This might point out that the plume impacts how exhausting Magellanic penguins should paintings to seek out meals.
“We believe that the Río de la Plata plume carries a great deal of nutrients into the coastal waters, making them very productive feeding grounds for the penguins,” mentioned Rebstock. “But winds will affect where the plume is distributed and how far penguins will have to go to reach it.”
A weaker plume might stay the penguins’ prey nearer in combination and nearer to breeding colonies, expanding a person penguin’s odds of catching fish. Magellanic penguins are also principally visible hunters. A more potent plume that adheres to the coast might impede visibility for the birds by way of making waters extra turbid, mentioned Rebstock.
The measurement and disposition of the plume might impact women folk greater than men as a result of male Magellanic penguins have a tendency to be higher, which lets them dive deeper. This can provide men a slight edge in catching meals, particularly in tough prerequisites, mentioned Rebstock.
“What we would like to do next is test some of these hypotheses by tracking male and female Magellanic penguins during the winter months, to see if they are feeding in the same locations and see how successful they are at obtaining food in different conditions,” mentioned Rebstock.
For researchers like Rebstock, that can be the following black field to open. But it’s going to additionally pose a logistical problem. Researchers have attempted to trace Magellanic penguins all the way through wintry weather the usage of satellite tv for pc tags, however the penguins are very efficient at taking them off.
Source: University of Washington