Weekly round-up: April 25

Great white sharks only gather in a few locations around the world (Wikimedia Commons)

While Steven Spielberg may have beachgoers across the globe fearing a great white shark lurks behind every wave, in reality the apex predator is only seen consistently in a handful of locations – and scientists have just discovered one more

Central California, Guadalupe Island Mexico, South Australia and South Africa have traditionally been the main ‘hotspot’ areas where significant white shark numbers are found, usually centred around large seal colonies, but a research team studying the species has found a new population in the Gulf of California.

Co-author and University of Delaware assistant professor Aaron Carlisle said: “It’s been about 20 years since a new ‘population’ of white sharks has been discovered. The fact that the eastern Pacific has so much infrastructure focused on white sharks and we didn’t know that there were these sites in the Gulf of California was kind of mind-blowing.”

However, while the find should be a boon for great whites – classed as Vulnerable to extinction by the IUCN and with numbers decreasing – the study also discovered higher rates of mortality in the species resulting from the fishing industry than has previously been estimated. For example, a 2012 study by the National Oceanic and Atmospheric Administration (NOAA) estimated the female adult mortality rate in the eastern Pacific at just two annually. In the Gulf of California, the team found that over several months an illicit fishery for the species killed at least 14 large white sharks, at least half of which appeared to be mature females.

“One of the big points of this paper was to raise the red flag and let managers and scientists know that this is going on and this population is here and needs to be studied,” said Carlisle. “Hopefully, it will be studied by some local researchers who are invested and working with the local fishing communities because these fishing communities are all heavily dependent on marine resources and fisheries.”
Publication Conservation Letters

Eradicating invasive non-native rat populations from islands not only increases bird populations, but improves the health of the seas around them.

Seabirds play a vital role in the nutrient cycle – feeding off fish in the open ocean and returning to the islands to roost, they excrete nitrogen-rich guano. This fertilises both the island itself and the waters surrounding it as nutrients are leached out through the water cycle, boosting the growth of coral, algae, sponges and other species.

A study led by Lancaster University monitoring 20 islands in the central and western Indian ocean found that those with existing rat populations had the lowest number of seabirds and seabird-derived nutrients, but importantly also found rapidly increasing bird numbers on islands where rats had been eradicated.

Brown noddies are among the seabird species thriving after the eradication of rats on their island (Ryan Hagerty/USFWS)

Co-author Matthieu Le Corre of the Université de La Réunion said: “Rats were eradicated on [the island of] Tromelin in 2005. Since then there has been an eight-fold increase in seabirds, and six species that were locally extinct because of the rats have restarted to breed after rat eradication. On Île du Lys, where rats were eradicated in 2003, surveys show there has been a ten-fold increase in seabirds since.”

Lancaster University’s Professor Nick Graham, principal investigator of the research, said: “This study adds to the weight of evidence suggesting rat eradication can have substantial conservation benefits to tropical island and adjacent marine ecosystems. The nutrient cycles that returning seabirds bring can bolster coral and fish assemblages. With climate impacts severely impacting coral reefs, management actions to boost the ecosystem are incredibly important.”

In March, a similar study showed the ecosystem on Alaska’s Hawadax – formerly known as Rat Island – had fully recovered in just 11 years after eradication of the rodents.
Publication Current Biology

The release of wildcats in the English countryside could “restore balance in ecosystems”, according to a wildlife charity behind the proposal. The species was driven to extinction in the country more than 200 years ago.

The Wildwood Trust has unveiled plans for a release programme, including breeding enclosures at its bases in Kent and Devon. The aim is to re-establish a “viable and self-sustaining wildcat population”, the trust’s conservation director Laura Gardner said. 

Wildcats are one of Britain’s few remaining native predators, and aid in ecosystem management by controlling the numbers of rodents and competing with other apex predators such as foxes.

A small population of wildcats in Scotland has been declared functionally extinct due to extensive hybridisation with domestic cats – any kittens born as part of the Wildwood programme before release sites in England are agreed upon will be transferred to Scotland where a project to introduce captive-bred wildcats is already in place.
Source BBC

Edinburgh Zoo’s latest arrival (RZSS)

Edinburgh Zoo has welcomed a northern rockhopper penguin chick to its colony, the first of the breeding season.

The Royal Zoological Society of Scotland, which owns and operates the zoo, is part of a European breeding programme to preserve the species. 

Found on islands in the southern Atlantic and Indian oceans, the species is classed as Endangered by the IUCN. Described as “scrappy and pugnacious” by the American Bird Conservancy, northern rockhoppers have a distinctive yellow brow and crest, with an orange bill and white chest. Weighing in at around 2kg, they are among the smallest crested penguins.

Sean Meechan, senior penguin keeper at Edinburgh Zoo, said: “Northern rockhopper penguins are endangered due to climate change, changes in marine ecosystems and overfishing, so it is really exciting to welcome a new chick to the zoo. The first 30 days are critical for their development, so we’ll [be] keeping a close eye on them at this sensitive time. 

“Last year we welcomed two Northern rockhopper chicks, Ronda and Blake, who have settled well into the colony. 

“We are also waiting for our gentoo eggs to begin hatching and are hopeful this will begin in the coming weeks.”
Source Edinburgh Zoo

Alpine meadows are at risk from early snow melt (Claudia Beyli)

Alpine snow cover has melted almost three days earlier every decade since the 1960s, posing a risk to vegetation in the region.

Snow on the ground protects plants from winter and spring frosts – early melt results in a lower survival rate – while an advancing start to the growing season results in fewer flowers and less leaf growth.

Researchers from the University of Basel also predicted snow cover at 2,500m could disappear a month earlier than today by the end of the century, while continuous snow cover for 30 days below 1,600m could become a rare occurrence.

Changes in the timing of vegetation budding and coverage have already been shown to negatively impact delicate ecosystems where the insects and animals that rely on them are unable to adapt their own migration or reproduction cycles.
Publication Climatic Change

Read Britain, Norway and the United States join forces with businesses to protect tropical forests

Watch Peregrine falcons nesting on Ely Cathedral

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