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Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand


Linklater, WL and Cameron, EZ and Minot, EO and Stafford, KJ, Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand, Wildlife Research, 31, (2) pp. 119-128. ISSN 1035-3712 (2004) [Refereed Article]

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Copyright CSIRO 2004

DOI: doi:10.1071/WR02067


Abstract Although feral horses are a common management problem in numerous countries, detailed and long-term demographic studies are rare. We measured the age and sex structure, and pregnancy, birth and death rates in a population of 413 feral horses in New Zealand during 1994每98 and used them to construct a model simulating population growth. Survivorship increased with age (0每1 years old = 86.8%, 1每2 = 92.3%, 2每4 = 92.4%, ≡ 4 years old = females 94%, males 97% per annum). Birth sex ratio parity, a slight female bias in the adult sex ratio (92 males per 100 females) and higher adult male survivorship indicated lower average survivorship for young males than females that was not detectable in mortality statistics. Pregnancy and foaling rates for mares ≡ 2 years old averaged 79 and 49%, respectively. Foaling rates increased as mares matured (2每3-year-old mares = 1.9%, 3每4 = 20.0%, 4每5 = 42.1%, ≡ 5 = 61.5% per annum). Young mares had higher rates of foetal and neonatal mortality (95% of pregnancies failed and/or were lost as neonatal foals in 2每3-year-old mares, 70.6% in 3每4, 43.2% in 4每5, and 31% in mares ≡ 5 years old). Population growth was 9.6% per annum (9.5每9.8, 95% CI) without human-induced mortalities (i.e. r = 0.092). Our model, standardised aerial counts, and historical estimates of annual reproduction suggest that the historical sequence of counts since 1979 has overestimated growth by ~50% probably because of improvements in count effort and technique.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Zoology
Research Field:Animal developmental and reproductive biology
Objective Division:Environmental Management
Objective Group:Other environmental management
Objective Field:Other environmental management not elsewhere classified
UTAS Author:Cameron, EZ (Professor Elissa Cameron)
ID Code:72608
Year Published:2004
Web of Science® Times Cited:26
Deposited By:Zoology
Deposited On:2011-08-29
Last Modified:2011-11-04
Downloads:6 View Download Statistics

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