Black Petrel, Procellaria parkinsoni
The Black Petrel (Procellaria parkinsoni) is also called the Parkinson’s Petrel. It is a large, black petrel, the smallest of the Procellaria. This species is an endemic breeder of New Zealand, breeding only on islands off the North Island, on Great Barrier Island and Little Barrier Island. At sea it scatters as far as Australia and Ecuador.
It’s a medium-sized, all black petrel except for pale sections on the bill. The wingspan is 110 cm on average. This bird is usually seen in the outer Hauraki Gulf in New Zealand from October to May. It was previously found throughout North Island and northwest Nelson but predators such as feral cats and pigs were the cause for their extinction on the mainland from about the 1950s. They are now restricted to a main colony on Great Barrier Island with 5000 birds over the summer, including about 1300 breeding pairs and 1000 “pre-breeders” that are seeking mates. There is a small colony on Little Barrier Island of about 250 birds.
The Black Petrel was placed under DOC Threat Classification System as Nationally Vulnerable. The International Union for Conservation of Nature or IUCN Red List listed this bird as Vulnerable. A land-based population research at their breeding colonies since 1995 indicates that the species is declining at a rate of at least 1.4% per year. With current survival rates, a fledged bird has a 1 in 20 chance of reaching breeding age (4+ years) and must breed 20 times successfully solely to replace the current population.
Breeding takes place from October to June in the Hauraki Gulf. The adults return to the colony in mid-October to clean burrows, and to pair and mate with the same partner. The male birds will return to the same burrow each year and try to attract another female if their mate does not return or if there is a “divorce”. The paired birds then depart on a “honeymoon”, returning to the colony again in late November when the females lay a single egg. Both of the parents share incubation of the egg for 57 days. The eggs can hatch from late January through February. Chicks will fledge after 107 days (15 weeks) from mid-April through to late June. Only about 75% of the chicks survive to fledge. Breeding success fell to 61% in 2011 for unknown reasons. The adults and the chicks migrate to South America for winter to waters off the coast of Ecuador. Only 10% of the fledged chicks survive during this first year. Juveniles will stay at sea in the West Pacific for 3 to 4 years until they are ready to breed. The survival rate is 46% during this time opposed to 90% for birds over 3 years old. At about 4 years old, pre-breeding birds will fly back to the colony to find a mate-this may take 1 to 2 seasons.
Black Petrels may range from the east coast of Australia all the way to the coast of South America between Mexico and Peru and the Galapagos Islands. The females and males forage separately and in different places, but it is not known why. They forage much closer to the Hauraki Gulf over the summer and in autumn while incubating an egg and raising a chick. They may feed at night or during the day. They will aggressively follow fishing boats and long line hooks and may dive up to 20 meters below the surface after baits. These birds can cover amazing distances. The longest recorded foraging trip for a bird from Great Barrier is 39 days. In addition to breeding birds, there are likely to be a further 6000 juveniles, pre breeders and non breeding birds at sea.
The following are the threats that these birds face at sea. Black Petrels are caught by commercial and recreational fishers both in New Zealand and overseas. Ministry of Fisheries research shows the Black Petrel is the most at risk seabird in New Zealand from commercial fishing, estimating that between 725 and 1524 birds may have been killed each year in the time period of between 2003 to 2009. The birds may be drowned by taking long line hooks after they are set or when they are being pulled onto boats. Inshore snapper and bluenose bottom long line fisheries are the greatest risks, especially where fisheries overlap with the foraging patterns of breeding birds. Reported deaths by fishers are low. Since 1996, there have been only 38 birds reported caught and killed in New Zealand waters by local commercial fishers, mainly on domestic tuna long-line and on snapper fisheries. Less than .5% of these boats in high risk fisheries had observers on board in any one year. The level of deaths in the fisheries happening outside of New Zealand waters is unknown. There are anecdotal capture reports from recreational fishers especially in the outer Hauraki Gulf where birds are commonly reported.
The following are the threats to the main breeding colony. On Great Barrier Island, feral pigs are known to dig up burrows and eat the eggs and chicks. The feral cats can kill adult birds on the ground or at the nest as well as the chicks. Cat numbers on Great Barrier Island are impacted by trapping by the Department of Conservation in the Whangapoua basin but there has been no specific protection of the colony to date. Kiore and ship rats are also on Great Barrier Island but the predation levels are between 1 and 6.5% per annum; kiore cannot eat through a Black Petrel egg. Risk to black petrel survival from a one-off event/events is important due to limited habitat for breeding.
Image Caption: Black Petrel (Procellaria parkinsoni). Credit: Aviceda/Wikipedia (CC BY 3.0)