# UKBirds

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## Leach's Storm Petrel

### Oceanodroma leucorhea

he Leach's Storm Petrel or Leach's Petrel (Oceanodroma leucorhoa) is a small seabird of the tubenose family. It is named after the British zoologist William Elford Leach.
It breeds on inaccessible islands in the colder northern areas of the Atlantic and Pacific. It nests in colonies close to the sea in well concealed areas such as rock crevices, shallow burrows or even logs. It lays a single white egg which often has a faint ring of spots at the large end. This storm-petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and will even avoid coming to land on clear moonlit nights. The largest colony of Leach's Storm Petrels can be found on Baccalieu Island of eastern Canada, an ecological reserve with more than 3 million pairs of the bird.
The Leach's Petrel, known in some rural areas as Carrie Chicks, is a small bird at 18-21 cm in length with a 43-48 cm wingspan. Like many other Storm-petrels, it has all-dark plumage and usually a white rump. However, dark-rumped individuals exist on the west coast of North America; they are very rare north of southern California, but the percentage increases suddenly on the United States-Mexico border where 90-100% of breeding birds are dark-rumped.
In Europe, it can be readily distinguished from the European Storm Petrel and the Wilson's Storm Petrel by its larger size, forked tail, different rump pattern and flight behavior. Identification in the Americas, however, proves more difficult. On the Atlantic Coast it is very hard to separate this species from Band-rumped Storm Petrels; identification involves characteristics such as the extent of white on the rump and flight pattern. Discerning this species from others is arguably hardest on the Pacific Coast, where the dark-rumped from can be confused with at least three other all-dark Storm-petrel species. Here, identification involves close attention to wingbeats and overall color. It has a fluttering flight, and patters on the water as it picks planktonic food items from the ocean surface. Like most petrels, its walking ability is limited to a short shuffle to the burrow. One interesting aspect of the bird is that contrary to most species, this bird gains telomere growth as they grow older. Telomere shortening in cell division limits the maximum lifespan of most other species. The lifespan of the Leach's Petrel is therefore theoretically limitless. This is a matter of debate, however. Studies have shown that while the telomere growth may have contributed to the eldest of specimens, young specimens exhibit telomeres that are longer, and shorten over time. The Leach's Petrel lifespan may be inconclusive, but there is no data to support the hypothesis that this species is possibly immortal.