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Research Profile
The establishment of Whiteheads (Mohoua albicilla) following translocation into Karori Sanctuary
Stephanie Hicks
Degree: MSc in Ecology
Supervisor: Dr Ben Bell
Institution: School of Biological Sciences
Victoria University of Wellington
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| Whitehead © Peter Reese |
Two groups of 30 whiteheads were translocated into Karori Sanctuary from Kapiti Island during August 2001 and May 2002. Initial survival in the first two months following translocation was significantly higher for the first translocation (60%) compared with the second translocation (27%). This is most likely due to the combined effect of time of release, a greater proportion of juvenile birds in the second translocation group, and to the presence of already established birds from the previous translocation. Though survival was low, the second translocation did provide mates for new pairs in the second breeding season. There was no significant effect of the release methods used on initial survival; however delayed release did result in birds, particularly males, dispersing further than females.
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| Whitehead © Peter Reese |
Nine territories were formed in the first breeding season, and seventeen territories established (plus one outside the main entrance) in the second breeding season. The length of each breeding season was longer in KWS than what is known elsewhere for this species. Productivity was also the highest recorded to date, with 3.7 and 3.4 fledglings being produced per female in each respective season. This resulted in 33 fledglings in the first breeding season and 61 fledglings in the second season. All pairs formed following the first translocation had double broods, but only three pairs in the second season double brooded. This is probably because most birds were inexperienced yearlings, although habitat quality may have been a factor. Most pairs were monogamous, but one case of polygamy occurred in each season. Incidences of delayed dispersal and helping behaviour also occurred in the second breeding season, with all cooperating individuals being male.
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Profile Stephanie completed a BSc in Ecology & Zoology in 2000 through Victoria University of Wellington. After receiving a scholarship from the NZ Federation of Graduate Women and the Miskel Prize in Zoology for 2000, she went on to graduate with a MSc in Ecology in 2004. Currently Stephanie is working for the Department of Conservation; and is involved in the recovery project for Otago (Oligosoma otagense) and grand skinks (Oligosoma grande). She also recently spent two months on Ulva Island working with Stewart Island robins (Petroica austalis rakiura) and South Island saddleback (Philesturnus carunculatis carunculatis) for the University of Otago. |
Annual adult survival (0.71) was comparable to other whitehead populations and annual juvenile survival and recruitment (0.55) was higher than known whitehead records. This resulted in a positive population growth in the period following translocation, with recruitment at replacement levels. It was estimated that the Karori Sanctuary area could hold ninety-one breeding territories, giving the area a sustainable population size of 546 – 728 individuals. Given the current rate of increase (64%), the KWS population could potentially reach this size within five years.
Whiteheads showed a distinct preference for certain habitat types within KWS, with older stands of mahoe dominated (Melicytus ramiflorus) mahoe-fivefinger (Pseudopanax arboreus) forest being preferred. Every territory (except one) contained pine trees, which were regularly used as song-posts and foraging sites. Pine forest (Pinus radiata) was also selected if there was a sufficient understory of mahoe and fivefinger. More pairs that formed in the second breeding season were found in this forest type than pairs that established following the first translocation, which monopolised the older mahoe stands. This trend in habitat selection supported predictive models in regard to settlement following sequential reintroduction, in that the first to arrive selected what is assumed to be the higher quality habitat first.
Territory size in the founding population ranged from 3.1 to 5.1 ha, with an average size of 3.4 ha. This significant variation in size was largely related to resource distribution, however the presence of neighbours and habitat barriers are believed to have contributed to the size of some of the smaller territories. Territories typically contained a gulley with a stream and gentle gradient; these territories would then extend up a ridge along which pine trees were found. Scrub vegetation and areas with a dense sub-canopy were also included, presumably for nest sites. Whiteheads generally avoided areas that consisted entirely of low scrub alone e.g. gorse scrub.Papers
- Hicks, S.J. 2004. 'The Translocation of Whiteheads (Mohoua albicilla) - from Kapiti Island into Karori Wildlife Sanctuary'. MSc Thesis. Victoria University of Wellington.
Glossary
Delayed release: A type of release design where individuals are held in captivity for a set duration prior to being liberated
Delayed dispersal: A form of breeding behaviour found in cooperatively breeding species whereby individuals from previous seasons remain within the natal territory
Helping behaviour: A form of breeding behaviour found in cooperatively breeding species whereby individuals from previous seasons assists a breeding pair in raising their offspring but do not breed themselves
Monogamous: When two individuals pair and mate only with each other
Recruitment: The number of offspring from the previous breeding season remaining within the population in the following season
Polygamy: When one male pairs and mates with more than one female
Article Ref #0011
Published Mar 21, 2007
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