Action: Artificially incubate and hand-rear seabirds in captivity
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- Five studies from across the world found evidence for the success of hand-rearing seabirds.
- One small study in Spain found that one of five hand-reared Audouin’s gulls Larus audouinii successfully bred in the wild.
- Four studies found that various petrel species (Procellariiformes) successfully fledged after hand-rearing. One controlled study found that fledging rates of hand-reared birds was similar to parent-reared birds, although a study on a single bird found that the chick fledged at a lower weight and later than parent-reared chicks.
Artificial incubation involves removing eggs from incubating parents and using an incubator to hatch them. Techniques can be extremely complex, with precision humidity and temperature control and turning of the eggs to ensure correct development Hand-rearing can be used with chicks from artificially-incubated eggs or with chicks removed from parents after hatching and involves manually feeding chicks until independence. Both techniques can be used to encourage parents to produce more offspring, or when naturally-raised chicks and eggs have low survival.
Supporting evidence from individual studies
A small study on Bermuda in 1971 (Wingate 1972) reported on the successful hand-rearing of a Bermuda petrel chick Pterodroma cahow. The chick was abandoned by one parent, causing its development to slow and it was not ready to fledge when it reached the normal age for departure (84 days). It was therefore hand-fed on blended squid and shrimp using a squeezable pipette. The chick reached a lower weight than most petrels, probably due to stunted growth before being hand-reared. It was released successfully but at a greater age than parent-reared birds fledged.
A small study at a captive-breeding centre in eastern Spain (Martínez-Abraín et al. 2001) found that, of five captive-bred, hand-reared Audouin’s gulls Larus audouinii released in 1992, one bird returned to the centre and successfully bred every year from 1995-2000. A second bird, released in 1995, returned in 1998 but did not breed. The released bird and its mate moved the location of their nest each year, each time nesting close to a captive pair also breeding. There were no significant differences between clutch size or hatching success of the released and captive pairs (an average of 2.6 eggs/clutch and 53% hatching success for released birds vs. 2.4 eggs/clutch and 67%). This study also describes the captive-breeding efforts, discussed in ‘Use captive breeding to increase or maintain populations’.
A replicated, controlled study on Cabbage Tree Island, New South Wales, Australia, in 1995 (Priddel & Carlile 2001), found that the fledging rate of 30 hand-reared Gould’s petrels Pterodroma leucoptera moved from their burrows to artificial nests nearby was not significantly different from control (unmoved, parent-fed) birds or from chicks provided with supplementary food (100% of hand-reared chicks fledging vs. 29/30 fed chicks and 29/30 controls). Hand-reared chicks were also significantly heavier than controls, but lighter than supplementary-fed chicks. Hand-rearing consisted of approximately 25 g of food every three days. This study is also discussed in ‘Provide artificial nesting sites’, ‘Translocate individuals’ and ‘Provide supplementary food to increase reproductive success’.
A replicated study in November-December 1997-9 (Miskelly & Taylor 2004) found that 118 of 239 common diving petrel Pelecanoides urinatrix nestlings (49%) were successfully hand-reared after being translocated to Mana Island, New Zealand, from other offshore islands. Chicks were between four and eight weeks old when caught and fed a krill-based paste (also containing calcium and other supplements) with a 12 ml syringe either once (in 1997) or twice (1998-9) a day until fledged. Fledging rates were higher in 1997 (58% of 90 chicks) than 1998 (40% of 100) or 1999 (53% of 49), but these differences were not investigated statistically. Information on translocation success and other interventions are discussed in ‘Use vocalisations to attract birds to safe areas’, ‘Provide artificial nesting sites’ and ‘Translocate individuals’. This study describes a technique usually used in captivity being used in the wild.
A small study on Bermuda in summer 1997 (Raine & Abernethy 2006) found that an abandoned Bermuda petrel Pterodoma cahow chick was successfully hand-reared from approximately three months old until fledging, 20 days later. The chick was fed on 60-90 cm3 of blended squid and shrimp in a 2:1 ratio, nutrient tablets and warm water. The chick was allowed outside to exercise its wing muscles for a week before eventual fledging.
- Wingate D.B. (1972) First successful handrearing of an abandoned Bermuda Petrel Chick. Ibis, 114, 97-101
- Martínez Abraín A., Viedma C., Ramón N. & Oro D. (2001) A note on the potential role of philopatry and conspecific attraction as conservation tools in Audouin's gull Larus audouinii. Bird Conservation International, 11, 143-147
- Priddel D. & Carlile N. (2001) A trial translocation of Gould's petrel (Pterodroma leucoptera leucoptera). Emu, 101, 79-88
- Miskelly C.M. & Taylor G.A. (2004) Establishment of a colony of common diving petrels (Pelecanoides urinatrix) by chick transfers and acoustic attraction. Emu, 104, 205-211
- Raine A.F. & Abernethy K.E. (2006) The hand-rearing of an abandoned Bermuda petrel Pterodroma cahow chick from Nonsuch Island, Bermuda. Conservation Evidence, 3, 4-5