In conjunction with Department of Conservation, Brent organised and participated in a New Zealand storm-petrel catching mission based on a boat in the Hauraki Gulf. The information below was written by Brent shortly after the ground-breaking trip, and has been edited slightly to include the latest information....

On 4 November 2005 a New Zealand storm-petrel flew into the cabin of a boat anchored just off Little Barrier Island in the Hauraki Gulf. Being the first bird handled since its rediscovery, this bird was banded, measured, photographed, and then released. Several feathers and a louse were also collected.

A catching trip aboard a boat in the Hauraki Gulf had already been planned for the first week of January, but a terrible week weather wise restricted our departure until Thursday 5 Jan. Six of us, Richard Griffiths (DoC), Halema Jamieson (DoC), Avi (local Maori representative), Rohan Clarke (Aus), myself and Brett Rathe (skipper) headed out early on Thursday morning.

We headed to a point that Brett expected to find the birds based on the prevailing conditions, and after 45 min or so had not seen one, so motored a short way towards the Hen and Chicken Island's. At the second chumming location we struck gold and had up to 3 birds around the boat at once. Over the next few hours we tried and tried to catch one, until we finally managed to get a bird onboard at 1430 hours! We used a large hand-net and a hoop-net, but due to the speed these birds move and the sea and wind conditions these were not successful. We were eventually successful with a modified throw-net. It was pretty fantastic to finally have one in the hand - something I'd dreamt about!

We banded, measured, and photographed the bird, and fitted it with a small transmitter attached to the tail. Several lice were collected from the bird, and a small blood sample taken for molecular analysis (Dr Bruce Robertson at Canterbury University in New Zealand is currently conducting the molecular analysis – if anyone has samples from other storm-petrels we would be interested in hearing from you - please email Brent). Upon releasing the bird it flew strongly and headed off to the east. Another few tantalising hours were spent trying to catch birds around the boat, but they all evaded attempts. The following morning we tried again to catch another bird, and at 1240 we were again successful. This bird was similarly processed and released with a transmitter. It also flew strongly, into the 25 knot wind, and with a rising 2 m sea we decided to call it quits mid-afternoon.

The transmitters attached were just over 1 gram, measuring approximately 12 x 6 x 6 mm (excluding aerial). We made a guess that the birds would be approximately 30 grams (now known to be correct), and figured that a transmitter 3% of the body weight should not hinder the bird (standard is about 3% of body weight). What also made me feel more confident about the size of the transmitter versus the bird was the fact that female storm-petrels lay the largest egg relative to body size of any bird (often kiwi are quoted as such in NZ but that is incorrect). Therefore, a female storm-petrel weighing 30 grams, may actually carry an egg roughly 23-24% of her body weight, or 7.2 grams - makes carrying a 1 gram transmitter seem easy (ED. correction storm-petrel eggs can be up to roughly 30% of the females' body weight!). We attached the transmitter to the base of the top two central tail feathers, using duct tape. This reduces attachment time (compared to glue and thread) and works well on larger petrels (such as taiko and grey-faced petrels) for 3 months or more. When the bird moults, the feathers and transmitter will drop-out, and it also seems a less likely attachment method to tangle or get caught (versus glue to skin or a harness)''

An ecstatic crew headed back to land. A day later, a slightly different crew (including John Ewen from The Zoological Society of London) headed out on 8 Jan and spent the next day and a half attempting to capture more birds. With very rough conditions on the second day we were again successful and were able to process and fit a transmitter to another bird. With three birds in 3 ½ days we had surpassed all expectations. Over the next week sorties over the Hauraki Gulf were conducted in an effort to locate the birds on land. We need to know where they breed so that the island they breed on can be assured of remaining rodent free (we assume it already is), and so that research into the breeding biology and population status of the species can be conducted. Unfortunately, only one bird was relocated, and this was at sea. Due to the short life of the transmitters used, the last survey was conducted on 16 Jan 2006. We are currently putting together a plan for next year...

Firstly I state that this work was undertaken with permission from the New Zealand Department of Conservation to capture, handle, and band these birds (Permit No. 0442) and approval to attach transmitters and to take blood sample from the birds was obtained from the Department of Conservation’s Animal Ethics Committee (AEC 108). Also, I have previous experience in all of these procedures, and our proposed research involved considerable research, consultation, and planning.

Regarding questions about the transmitters. All transmitters employed were within the recommended guideline weight of 3% of body mass. As previously mentioned, we felt this would not be a hindrance due to the considerable weight gains females experience during egg development. Attachment via the tail was deemed best because transmitters would be lost during tail moult and based on premature moulting of tail feathers in other species equipped with such devices, transmitters can be easily “dropped” if they are causing difficulty to the bird. Transmitters were attached to two central tail feathers only and so regrowth of only these two feathers should not be at significant cost to the bird. The aerial of each transmitter was a single strand of stainless steel wire. It is very flexible and would bend easily in a narrow or confined space (e.g., a burrow), and being a single strand would be almost impossible to snag. The use of transmitters on such a small bird is of course something that needs to be carefully considered: however, this is not the first time such devices have been used on storm-petrels (see Nygard T. and Einavik K. 1991. Radio-tracking of a British Storm Petrel Hydrobates pelagicus proves a probable new breeding-site in Norway. Seabird 13: 59-62.).

As for the reasons for attaching these transmitters, we believe the knowledge gained vastly outweighs the low risk of using the devices. At present, we have no idea where these birds nest, and whether or not they do actually nest in New Zealand. We currently believe that they breed on a small rat-free island in the Hauraki Gulf, near Auckland, and that one of the possible reasons for an increase in sightings in recent years, is that they have since re-colonised a nearby island that has had rats removed in the last few decades. If this is true, it is imperative that we discover where they breed in order to make sure that rats do not reinvade, and possibly worse still, invade the island they have persisted on over the last 150 years. The Mokohinau Group has been suggested as one place where they might breed, based on the fact that one or two of the stacks have remained rodent free. Little Barrier Island could also be a possibility, as could any number of the islands in the Hauraki Gulf. Burgess Island in the Mokohinau Group DOES allow day visitors, and the stacks that remained rodent free, are close to this island. It does not permit camping, but people CAN and do freely land on the island. It would be a disaster to re-discover a species after 150 years of presumed extinction, only to have it become extinct because we didn’t know where it bred until rats got there. Although this is very unlikely, and counter measures are in place on these islands, with increasing numbers of pleasure craft and other vessels in this very busy area, it is important that we find this information out as soon as possible. What’s more if we can find their breeding site then we can start to gather basic biological information, as well as make an assessment of the population size. At present we believe there may be 100-200 birds (based on then numbers of birds we see in the Gulf), but possibly more – at this stage this is complete conjecture. One could argue that the birds are doing ok without human intervention….but are they? We really have no idea. The fact that birds are now being regularly seen may have something to do with an increase in numbers, as mentioned above, but could also be due to the fact that people are actually out there looking for them now. Pelagic birding in New Zealand is relatively new, and it is interesting to note that several trips into the Hauraki Gulf on pelagic birding trips prior to the rediscovery failed to detect the birds. Perhaps they were there all along, maybe in slightly lower numbers, but just weren’t being picked up? Realistically transmitters are the only way of locating the breeding site, which in turn will give us a crucial insight into their biology.

The transmitters used had a limited range at sea from sea level, but we are confident that had the birds been on land, or even in burrows then they would have been detected from the work we conducted, both during the day and at night based on some of these areas. Trials with the transmitters from land, sea, and air support this.

No birds were carrying eggs at the time they were captured, and based on what we assume, breeding should have been well underway at this time. If birds had been carrying eggs, then transmitters would not have been attached. The birds have not been sexed using measurements, but from the material taken, molecular sexing will be undertaken. Females should be larger than males, but we need to know the sex to be able to work out sex-specific differences, a catch-22 situation. It is worth noting that the sex of only one of the museum specimens is known, being a male (as far as I can ascertain): however, these samples will also be sexed using molecular methods.

As for information about the morphometrics, taxonomy, etc., this will all be published in due course. We are currently putting together a report for the Ornithological Society of New Zealand’s Rare Birds Committee as well as other material. This report will have the full details for the Committee to make a formal decision on the case, and at this stage full analysis of the photos, measurements, etc are still be carried out. I’m interested to hear that there are already rumours about the bird being in a new genus, and would be interested to know why this is being suggested. We will not be in any position to seriously consider this until the molecular work has been done and the photos etc have been properly assessed, even if this was a possibility. The molecular work is currently being conducted, and we expect some sort of outcome by April. With little point in doing a superficial analysis, this will all take time so that the samples can be compared not only with the museum specimens, but a host of other storm-petrel taxa. The work is currently only funded by Dr Robertson, something he should be congratulated for. As mentioned in the previous email, we are keen to hear from other workers who may have material from other storm-petrel taxa.

I hope this all goes a little way towards answering your questions. It is worth noting that this whole project has been ongoing since the first sighting of NZSP in 2003, with a lot of thought and consideration having gone into the best approach. It should also be noted that one of the challenges of reporting this type of work in real-time (a rare thing!), is that it seems from a spectators perspective to take forever for results and published material to appear. I can assure you this is happening.