Guest blog by Dr Steffen Oppel, Senior Conservation Scientist, RSPB Centre for Conservation Science
On 22 May 2015, the RSPB expedition team arrived on Henderson Island (Pitcairn Group, UK Overseas Territory) to better understand the ecology of this remote and rarely visited island. Over the next month the team will collect more data on vegetation, landbirds, rats, and seabirds, before being relieved by another crew at the end of August. You can read part 1, part 2 and part 3 of the Henderson Island science expedition here.
Finding Henderson petrel and Murphy’s petrel nests
Henderson Island used to be a paradise for nesting seabirds until humans discovered the island and introduced rats. The RSPB crew has so far marked 75 nests of two petrel species, the Henderson Petrel, which is endemic to the island and nests nowhere else, and the Murphy's Petrel, a species that also breeds on other islands in the South Pacific.
Photo of Murphy's Petrel by Tara Proud
While the Murphy's Petrels nest near the beach and have all started laying eggs in early June, the Henderson Petrels nest in the dense forest in the interior of the island. As a species adapted to travel thousands of kilometres across the open ocean, petrels are not really nimble tree-climbers. Yet, to take off from the forest, they need to scramble to the top of trees or bushes, which they do amazingly well using their hooked bill.
Installing motion sensor nest cameras reveals alarming footage
Unfortunately, that hooked bill is not really used to fend off rats. All the Henderson and Murphy's petrel nests that have hatched fluffy little chicks were attacked by rats within a few days, and no chick has survived for more than a week.
Photo of Murphy's Petrel chick by Tara Proud
The RSPB team has installed motion-sensor cameras at several nests to document for the first time the nest attendance pattern of Henderson Petrels, and to record the gruesome predation events, as we’ve also done on Gough Island. The typical chain of events is that an adult feeds its chick multiple times, and soon after the adult has left to gather more food at sea, a rat enters the nest and kills the helpless chick with a bite into the neck. Amazingly, some rats seem to kill the chicks without eating them.
How the petrel populations on Henderson Island are maintained given the ubiquitous rat predation is somewhat mysterious. Historic populations must have been many times larger than those of today, and with rats on this island, the Henderson Petrel appears to be heading towards extinction, slowly but certainly.
Crew change over in August
Over the next few month the team will collect more data on vegetation, landbirds, rats, and seabirds, before being relieved by another crew at the end of August.
The Henderson Island expedition is funded by The Darwin Initiative and David & Lucile Packard Foundation.
Find out more about our Henderson Island Restoration Programme
In June this year, three more tags were attached to sociable lapwings in Kazakhstan so that we can follow their migration in autumn. Five more will be fitted in August, so this year we should have at least eight birds to track - find out more from the field in June on the Swarovski Optik Nature Blog, and then follow progress during the year on The Amazing Journey website.
Guest blog by Dr Jennifer Lavers, Conservation Scientist, RSPB Centre for Conservation Science
On 22 May 2015, the RSPB expedition team arrived on Henderson Island (Pitcairn Group, UK Overseas Territory) to better understand the ecology of this remote and rarely visited island. Over the next month the team will collect more data on vegetation, landbirds, rats, and seabirds, before being relieved by another crew at the end of August. You can read part 1 and part 2 of the Henderson Island science expedition here.
Catching fish to examine for plastic contamination
After 4 weeks of fairly breezy weather the wind calmed down for a single day this week, offering the first opportunity to swim across Henderson's reef, watch sharks and catch some fish patrolling the outer reef edge. One shark also took the opportunity to come onto the reef and promptly beached itself in front of the RSPB crew, some of whom were at the time contemplating to go for a swim (but then decided otherwise).
Photo of East Beach, Henderson Island by Tara Proud.
The fishing opportunity also provided stomach contents of previously unsampled fish, which were immediately examined to see whether they contained plastic. Henderson Island is one of the remotest places on the planet, yet the amount of plastic garbage on the beach is remarkable. As an experienced seabird biologist studying plastic contamination of seabirds and the marine environment, I have encounted and weighed more than 15,000 pieces of plastic along four short transects (a painstaking task that would be impossible without assistance from some very dedicated helpers).
Items are sorted by type (e.g., fishing float) and origin, providing information on the source of the problem, and therefore, possible solutions.
Photo of East Beach, Henderson Island by Tara Proud.
Some very unexpected items have been found washed up on the beaches of this uninhabited island: dozens of toothbrushes, hair combs, hundreds of cigarette lighters, bottles from as far away as Scotland (Famous Grouse Whisky), two toy tea cups, numerous toy car tyres, and a kids water pistol.
Over the next few months the team will collect more data on vegetation, landbirds, rats, and seabirds, before being relieved by another crew at the end of August.