The Mystery Of The Disappearing Female PenguinsPosted on February 21st 2019
Very close to SouthAmerica’s Southern tip thousands of female Magellanic penguins seems to bevanishing from their nests. This species of penguin is native to the Patagoniaregion of South America and when not breeding Magellanic penguins migrateNorth, heading towards Uruguay and Brazil where they hunt for anchovies that livein the waters of that part of the world. Over the last ten years thoughconservationists have witnessed a disturbing trend, some of the migratingpenguins swim far too North, often hundreds of miles away from where they breedand end up getting stuck there.
Never return home
According to arecent study, thousands of penguins fail to return following their annualmigration. Some end up being stranded on the beaches of Brazil Argentina andUruguay whilst others wash up dead with empty stomachs or worse polluted withplastic waste. What is very strange is about two-thirds of the strandedpenguins are female. Scientists of course wanted to find out what was happeningand why females were mainly affected.
Tagging a group ofpenguins
A team ofresearchers tagged 14 Magellanic penguins, eight males and six females with GPSmonitors and then watched what they did after the end of their breeding periodin 2017. After a few months of observing the group the team established apattern. During the migrations of summer and spring, they found that malestended to stay closer to their breeding grounds in Patagonia and dived deeper.In contrast, females stayed closer to the surface of the ocean but migratedmuch further North than the males.
Combination ofnatural and man-made threats
When the femalepenguins arrived in the waters off the coast of Uruguay and Southern Brazil,they tended to gravitate to standing hot-spots. These sites trap the penguinsmost likely through a combination of strong currents that prevent the penguinsfrom swimming back home and man-made threats such as pollution in the waterthat is the result of oil development and marine transportation. There are alsofishery related threats such as bycatch and lack of prey.
Body size isprobably the main reason
Ultimately the mainreason female penguins seem to be disproportionately affected might come downto something as simple as body size. The researchers say that female Magellanicpenguins are smaller than their male counterparts which means it is probably harderfor them to compete for food in the Southern waters which are crowded. It alsomeans it is more difficult to fight against strong currents in the North.
The entirepopulation is at risk
Smaller bodies alsolikely mean the females are probably more sensitive to ocean temperatures whichmeans they probably seek out warmer waters in the North and avoid deep dives inthe cold ocean. The study is just the first step researchers are taking towardsunderstanding the mystery behind the penguin strandings. What is clearaccording to the researchers is that a decreasing number of female penguinsseem to be returning to their breeding grounds each year. This means the entireMagellanic penguin population could be at risk in the not too distant future.