How translocation affects the activity, home range and pair-bonds of great spotted kiwi (Apteryx haastii)

Abstract

Translocation of rare and threatened species is one of the tools utilized by wildlife managers in New Zealand for conservation purposes. There is a general trend towards increased use of translocations onto managed mainland islands, with kiwi one of the more common species to be translocated. Great spotted kiwi (GSK) or roroa/roa are highly cryptic with isolated habitat and low numbers making them difficult to study and therefore less studied than more accessible species. GSK are listed by the National Threat Classification Series as ‘nationally vulnerable’ with the 5,000 to 20,000 mature individuals facing ongoing or predicted decline. The parameters of this threat classification ranking include assumptions of total population size, population trends, geographical range and whether the birds are directly or indirectly affected by humans. The Captive Management Plan for the Kiwi Recovery Group identifies that the gradual decline in GSK populations is related to recruitment failure. There is currently a material decline in kiwi numbers due to predation pressure. Unless a practical solution to this problem can be found in the near term, GSK populations will be in crisis. On mainland islands it is not feasible to fully eradicate predators or cost effective to erect a predator proof fence. GSK must therefore co-exist with mammalian predators . Translocations have become an increasingly attractive tool to help manage and maintain individual populations. The Arthurs Pass-Hurunui GSK, as the smallest and most isolated population, are at greater risk of local extinction than most populations. In a joint venture between the Department of Conservation (DoC) and the community-run Nina Valley Recovery Group (NVRG), the Nina Valley GSK sub-adult population was supplemented with genetically diverse birds from the Hawdon Valley in April 2015. Social behaviour of kiwi is complex and many of their behaviours are not well explained or studied. There is a risk that unless the exact mechanism for social behaviours and interactions is understood, the translocation process may unintentionally disturb bonded pairs causing divorce. It has been postulated that pair stability may be correlated to territoriality in kiwi. Although there is partially applicable literature pertaining to dispersal from a translocation release site, it has circumstances that differ from the composition of this translocation. The literature is also deficient on the effects of translocation on those birds in residence and on home range creation for newly transferred birds. Home ranges of unrelated birds do not usually share a common boundary. Therefore impacts on the existing birds at the recipient site might be expected. In this study, eight individual paired adult GSK were translocated (wild to wild) from the Hawdon Valley (Arthurs Pass National Park) to the Nina Valley (Lake Sumner Forest Park) in the northwest of the South Island of New Zealand. The GSK were released near areas of five known resident, previously translocated captive reared sub-adults. Using radio telemetry, all subject birds were tracked for four months pre translocation and six months post translocation with activity data collected. It was found that three of the four pairs were likely still pair bonded six months post translocation, along with the one captive reared pair. The activity of the wild birds increased overall from pre to post translocation with no change from the captive reared birds. All captive reared birds retained their previously held territories while only one pair of the released wild birds remained near their release site. This research has a high level of importance, as New Zealand is a significant leader in the international community in translocations. The research can help ascertain potential negative outcomes and assist in developing management processes that can be put in place to mitigate such negative outcomes. It is unlikely that New Zealand will be able to rid the environment of all mammalian predators in the wild in the near term due to limitations in technology and public consent; therefore translocations will likely continue to be a significant contributor to saving and preserving local biodiversity.