Problems faced by the existing two breeding sites

Among the existing two breeding sites of Torishima and Senkaku Islands, Torishima is much larger and there are approximately 1655 individuals as of May 2005 according to Hasegawa's estimation. The each of the breeding sites faces issues concerning conservation. Torishima is a volcanic island thus its biggest issue is that the breeding site is always faced with the risk of eruption. If a large eruption occurs during the breeding season much of the breeding population can be lost. On the other hand, it is difficult to conduct studies and conservation activities in Senkaku Islands. Due to these backgrounds, the importance of establishing a third breeding site for enhancing reliability of the population recovery has long been called for among those involved in conservation of the Short-tailed Albatross.

Island where the Short-tailed Albatross used to breed.
Before the over-hunting in the Meiji era there were breeding areas all over the northwestern Pacific (red dots) besides the present two breeding sites (green stars)
(Created based on Hasegawa 1995)

Making Ogasawara the third breeding site

Discussion among relevant parties including those in charge of wildlife conservation in the US government and researchers interested in the recovery of the Short-tailed Albatross as national endangered species of the US led to launching of the project to establish the third breeding site of the Short-tailed Albatross in Mukojima of the Ogasawara Island chain. Mukojima is located approximately 350km to the south-south-east of Torishima, the largest breeding site of the Short-tailed Albatross. This site was chosen as the candidate for a new breeding site because;

1) Mukojima group used to be a breeding site of Short-tailed Albatross before the over-hunting in Meiji-era and a small number of individuals have been currently observed landing there,

2) there is no danger of volcanic eruption,

3) relative species, Black-footed and Layan Albatross breed on Mukojima. They have a potential to attract Short-tailed Albatross.

4) Chichijima, the center of the Ogasawara Islands, can be used as the base for conservation activities and for procurement of food and supplies.

How to attract Short-tailed Albatross – transplanting chicks, artificial rearing

In order to attract Short-tailed Albatrosses in Mukojima, the decoys and sound playback proved to be effective at Hatsunezaki in Torishima was used. However, this method required almost 15 years to establish a breeding site even though it was within the same island. A new method being considered for implementation in Mukojima involves transporting chicks hatched in Torishima and making them fledge from Mukojima. The Short-tailed Albatross is said to remember the site it was raised, and return to the site several years later when they are ready to breed themselves. This project tries to artificially rear chicks at the new site over a certain period of time and fledge them from there so as to increase the number of albatrosses returning to the site for breeding in a shorter time.

Artificial rearing of chicks in an uninhabited island will require refrigerators and a minimum level of living facilities, thus require extensive preliminary studies and preparation. As for transporting chicks, it was being considered to test with Black-footed Albatross, closely related to Short-tailed Albatross but under less risk of extinction before conducting it directly with the Short-tailed Albatross.

As for the project site, there were several candidate sites as Mukojima group is currently uninhabited and there are numerous existing breeding sites of seabirds. The site needs to be selected based on several criteria, such as present and current distribution of albatrosses, ease of berthing for transportation of goods and installation of accommodation facilities. The possible candidates being considered were Yomejima, Nakodojima and Mukojima.

Understanding and cooperation by local people are indispensable

Ogasawara Islands is designated as a national park and has many restrictions for conservation such as prohibition of camping and building of artificial structures. In order to protect the endemic species from alien species, transportation of goods from an island to island is also under strict inspection. Furthermore, vegetation of Mukojima islands is significantly damaged by feral goats and the Tokyo Metropolitan Government is currently leading a vegetation recovery project. Moreover, consideration for local industries such as tourism and fisheries is also important. Thus, this project will be promoted by overcoming legislative and regulatory issues and by ensuring sufficient communication with relevant stakeholders of the local government, fisheries, tourism, and nature conservation.

Preparation for the next step

In March 2005 a staff from the Yamashina Institute for Ornithology together with Hiroshi Hasegawa (professor of Toho University) visited Ogasawara Islands and selected the northwestern part of Mukojima as the candidate site for the project. Following this, an environmental impact assessment was conducted by experts of various biological species and the results indicated that the implementation of the project does not have major problems. Furthermore, the institute organized several explanatory meetings in Chichijima and Hahajima in order to obtain understanding of the local people who are highly concerned with the local nature conservation.

After such preparatory work, the 30 Short-tailed Albatross decoys were installed at the project site located in the northwestern part of Mukojima.

As for artificial rearing of the transplanted chicks, a trial experiment has been conducted using a closely related species in order to clear out any problems that may occur. First of all, experimental rearing of Laysan Albatross Phoebastria immutabilis chicks was conducted in Kauai Island in Hawaii from March to July 2006. Ten chicks were transported from Midway Island and were artificially reared, and four of them successfully fledged. Among the six others, five died of infectious disease and bad weather and one is being reared at the Monterey Bay Aquarium as it cannot fly (*). Taking account of the lessons learned by this experimental rearing, second trial of Black-footed Albatrosses was conducted in Ogasawara Islands from March to June 2007. Ten chicks transported from Nakodojima to Mukojima were artificially reared and nine of them successfully fledged. Good results were obtained indicating that compared to the chicks reared by wild adult birds, the artificially reared chicks were no significant different in body sizes evaluated by multiple indices, and their body weight at the time of fledging was even a little heavier.

Based on these results, the project obtained the approval of the "Short-tailed Albatross Subcommittee of the Wildlife Conservation Measures Committee" of the Ministry of the Environment and it was decided that ten chicks of about 40 days old are transported from Tsubamezaki breeding site in Torishima and are artificially reared in Mukojima.

The Short-tailed Albatross becomes about 1.5 times bigger than the Laysan Albatross or the Black-footed Albatross experimentally reared, and they are much more sensitive to human presence. Thus it became an even bigger challenge. The researchers were working hard to successfully raise the chicks for the further recovery of the population of the Short-tailed Albatross.

(Click to see the bigger image)

(*) The details regarding the experimental rearing of the Laysan Albtross can be found in Harada, T., et al. 2008. An Artificial Rearing Experiment of Laysan Albatross Chicks. Journal of the Yamashina Institute for Ornithology, 39(2): 87-100.

Translocation and Hand-rearing of Short-tailed Albatross

Each February during 2008-2012, 10-15 Short-tailed Albatross chicks (30-40 days old) were captured and translocated from the main colony, Tsubame-zaki, on Torishima to Mukojima (Fig. 1a). In total 70 chicks were translocated: 31 female and 39 male. Different nests at Torishima were selected each year to prevent individual pairs experiencing apparent breeding failure more than once.

The chicks were placed in individual ventilated wooden boxes (40 x 40 x 50 cm) with sides lined with sponges against shock to prevent injury during transit and an absorbent sheet on the bottom (Fig. 1b). Box lids were fitted with thermometers to monitor internal box temperature. We opened the ventilation hatch when the internal box temperature exceeded 35°C.

Based on the results of Black-footed Albatross translocation, we decided to transport Short-tailed Albatross chicks by helicopter rather than by boat, despite the additional cost. To reduce the risk of helicopter/albatross collisions on Torishima, the boxes were carried by field personnel to the top of the 120-m high Tsubame-zaki, where they were loaded onto a helicopter and transported for 90 minutes (350 km) south to Mukojima. Upon arrival at the helicopter landing site, chicks were carried 1 km to the release site. As before, we removed chicks from their boxes and placed them 5–10 m apart on flat ground devoid of natural nest depressions. Total transit time was 6–8 hours.

On the day following release, a numbered plastic identification band (Y01–Y74) was placed on the left leg of each chick. Scheduling of Short-tailed Albatross chick translocations was also adjusted according to weather forecasts for the source colony and release site.

During the first 2–5 days following translocation, 80–156 g of pureed therapeutic pet food (Prescription Diet a/dTM) and 300 ml of lactic Ringer’s solution or physiological salt solution, diluted twice by spring water, were administered daily to facilitate recovery from the stress of moving. Thereafter, we presumed the birds had recovered from this stress, and they were subsequently given darkedged-wing flying fish, Japanese common squid and canned oil sardine or Japanese sardine, plus Pacific krill. Short-tailed Albatross chicks were given 300–900 g of a mixture of these foods daily according to their daily metabolized energy per unit body mass (840 kJ kg-1) estimated from related species and the energy density of each food.

This feeding regime was continued until chicks were about 100 days old (mid-April), when chick body mass was at its maximum. We then gradually reduced the amount of food by 50–66% to decrease chick body mass by 20–30% prior to fledging. We administered the pureed foods and probiotics for the first 16–30 days, and then gave chopped or whole foods for the following 69–72 days. We also administered appropriate amounts of vitamin complex tablets (Mazuri Vita-Zu Bird TabTM, Mazuri Auklet VitaminTM). We gave 300–450 ml liquid containing 95% spring water and 5% clean seawater daily. For all chicks, feeding commenced on the day following release. Although feeding was continued until fledging to increase their post-fledging survival, amounts were limited to 100–300 g food and 30–300 ml of liquid every two or three days for 2–3 weeks prior to anticipated fledging.

There foods were kept cool in an insulated bin until arrival at the hand-rearing site and were heated in 50°C water just before feeding. The therapeutic pet food and pureed food was administered using 350 ml cartridges and caulking guns (Fig. 2a) through a silicon tube. We used 450 ml syringes fitted with a silicon tube to give liquid. Short-tailed Albatross chicks were always restrained with fleece blankets and handled by two persons to prevent injury during feeding. To minimize stress, handlers approached Short-tailed Albatross chicks in single file. We maintained high levels of hygiene by using disposable gloves for preparing meals and feeding activities. We sterilized all feeding equipment using 70% ethanol and no equipment that contacted chicks was reused without being sterilized. Used equipment was soaked in soapy and chlorine solutions recommended for baby bottles overnight.

Fledging success of hand-reared was 99% overall (69 of 79) during 5 years translocation. Growth of hand-reared chicks was comparable to that of naturally reared chicks, although hand-reared chicks were slightly larger at fledging (Fig. 3). Hand-reared birds had similar or better overall health than naturally reared birds, based on analysis of blood chemistry health indices, although the analysis indicated possible muscle stress in hand-reared birds (elevated levels of aspartate aminotransferase and creatine kinase). The techniques developed in our studies have broad-reaching implications for the future conservation of threatened populations of other surface-nesting seabirds. For more detailed information see Deguchi et al. (2012, 2014).