By Kaja Heising
The Atlantic puffin is an iconic bird in the Channel Islands. One of the southernmost populations, those breeding on Jersey and the other Channel Islands belong to the English-Channel or French-Atlantic sub-population.
Puffins spend the winter at sea and come ashore to breed in colonies. Usually they arrive in the Channel Islands around April and leave again in July. They have a slow reproductive cycle, not breeding until six years of age, and then only laying one egg per year. Typically, for breeding, puffins return to the sites where they hatched by themselves and Jersey, therefore, plays an important role for the annual life-cycle of this sub-population.
Although there are still good numbers of puffins globally it is listed as Vulnerable with a decreasing population-trend in the IUCN Red List of Threatened Species. No sub-populations are listed separately and it is highly possible that the French-Atlantic sub-population is even more endangered. Annually, about 580,799 pairs breed in the UK, Isle of Man and Channel Islands. Nevertheless, the numbers of the French-Atlantic sub-population are relatively low and have shown a continuous decrease during the 20th Century. Conservation Status of Jersey’s Birds lists the puffin as RED with a severe breeding population decline.
Population-development of Atlantic puffin on Jersey between 1998 and 2015.
The reasons for the puffin’s decline on Jersey are not completely understood and may vary with location. Several causes may play a role: puffins usually nest on offshore-islands free of mammalian predators. Most of the introduced mammalian predators, like the brown rat, black or ship rat, domestic cat or American mink, are good climbers and can also reach the puffins’ nest-holes on steep cliffs. The puffin is, therefore, especially vulnerable to these invasive species. Also native seabirds like herring gull, lesser black-backed gull and great black-backed gull might be a cause of puffin declines through kleptoparasitism or direct predation.
Human disturbance through tourism and general boat-traffic at the breeding sites might play a role in decreases. However, there is contradictory evidence: after a tourist-hotspot around the puffins’ nesting sites at Jersey (Plémont Holiday Village) was closed in 2000, a recovery of the population was not seen. This might be an indication that human-presence had little or even no effect on the Jersey-population.
Indirect impacts like climate change cause loss of the puffin’s food supply in many colonies. In the English Channel, rising temperatures and other indirect factors like pollution of the sea may play an important role as well. Moreover, one particular fish species, snake pipefish, has increased in number in the region around Jersey and may have been fed to nestlings, as has been recorded in UK, Norway or Iceland for instance (abstract here), although it is inedible for young puffins. Herring, capelin or sandeel should actually form their main diet.
There may have been a population of 200-300 pairs on Jersey during 1911-1914, decreasing rapidly from 1915 to only 22 pairs in 1998 and as few as two individuals at the time of writing.
My study focussed on recent temporal changes to try to identify of the current status of the Atlantic puffin population on Jersey. Assuming that climate change may play an important role for the puffin’s decline, temperature was correlated to the population size.
The methodology used to estimate the number of puffins between 1911- 1915 is undocumented and unlikely to be based on scientific evidence. However, the records of the high numbers in 1911-1914 and the drastic decline in 1915 were both collected by the same person (Roderick Dobson). Therefore, although the accuracy of the exact numbers is questionable, it can be assumed that there were high numbers of puffins present at Jersey, which then had a drastic decline. The reason for such a dramatic decline within only four years remains unknown. It is clear though that Jersey has never seen numbers of puffins like that again.
Due to a higher human population-density on Jersey, the puffin’s distribution might be restricted by invasive predators and by human presence. Brown rat began occurring on this island in the 18th Century, the black rat was introduced in Roman times. Avoiding pressure from rats, the puffins on Jersey may have become restricted to breed on sites which invasive mammalian predators find harder to access. These alternative breeding sites are small and poor-quality, areas like gaps along the cliffs instead of the commonly used burrows on cliff-tops.
Although the puffin is considered a flagship species of the Channel Islands, they have not been studied sufficiently and very little is known about their local ecology. The causes for the puffins’ decline on Jersey are still not fully identified. Although this analysis did not show any correlation to it, climate change as a factor should not be neglected as a potential main reason for the puffins’ decline in the English Channel. While the puffin might have resisted any single factor causing pressure on its population, the combination of all these factors together may be the causation for the eventual decline. Anthropologically disturbed areas, invasive mammalian predators, rising temperatures, decline in prey availability, and change in available fish species… summing up these factors – they were tough enough to effect the puffin’s population in the end.
With few actions taken, or possibly even feasible, to conserve the colony on Jersey, effort should be put into the puffins’ conservation throughout the Channel Islands, to prevent the same fate on the other islands as is happening on Jersey, where the puffin will, sadly, be extinct soon.
Acknowledgements
This assessment was written for the module “Invasive Species and other Drivers of Distribution Change” as part of the Master of Science class “Animal Behaviour: Applications for Conservation” at Anglia Ruskin University, Cambridge. I am grateful to Paul Aked, senior Meteorologist at the Meteorological Section of the Department of the Environment, Jersey for providing me with data on climate.
The puffin photos used here were taken in Iceland by Nicolas Guillod.
The full report Last chance to see? Analysis of temporal changes of the Atlantic puffin (Fratercula arctica) population at Jersey, Channel Islands can be read here
Kaja Heising, MSc Animal Behaviour: Applications for Conservation, Anglia Ruskin University, Cambridge
