| Records |
| Author |
Cameron, E.Z.; Linklater, W.L.; Stafford, K.J.; Minot, E.O. |
| Title |
Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser? |
Type |
Journal Article |
| Year |
2000 |
Publication |
Behavioral Ecology and Sociobiology |
Abbreviated Journal |
Behav. Ecol. Sociobiol. |
Volume  |
47 |
Issue |
4 |
Pages |
243-249 |
| Keywords |
Maternal investment – Equidae – Equus caballus |
| Abstract |
In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase. Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring. Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing more in their offspring. |
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2019 |
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Linklater, W.L.; Cameron, E.Z.; Stafford, K.J.; Austin, T. |
| Title |
Chemical immobilisation and temporary confinement of two Kaimanawa feral stallions |
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| Year |
1998 |
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New Zealand veterinary journal |
Abbreviated Journal |
N Z Vet J |
| Volume |
46 |
Issue |
3 |
Pages |
117-118 |
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English |
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0048-0169 |
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PMID:16032032 |
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refbase @ user @ |
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412 |
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Linklater, W.L.; Cameron, E.Z.; Minot, E.O.; Stafford, K.J. |
| Title |
Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand |
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Journal Article |
| Year |
2004 |
Publication |
Wildl. Res. |
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31 |
Issue |
2 |
Pages |
119-128 |
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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 1994–98 and used them to construct a model simulating population growth. Survivorship increased with age (0–1 years old = 86.8%, 1–2 = 92.3%, 2–4 = 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 (2–3-year-old mares = 1.9%, 3–4 = 20.0%, 4–5 = 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 2–3-year-old mares, 70.6% in 3–4, 43.2% in 4–5, and 31% in mares ≥? 5 years old). Population growth was 9.6% per annum (9.5–9.8, 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.</p> |
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Equine Behaviour @ team @ |
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3695 |
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Linklater, W.L.; Cameron, E.Z.; Stafford, K.J.; Veltman, C.J. |
| Title |
Social and spatial structure and range use by Kaimanawa wild horses (Equus caballus: Equidae) |
Type |
Journal Article |
| Year |
2000 |
Publication |
New Zealand Journal of Ecology |
Abbreviated Journal |
New Zealand J. Ecol. |
| Volume |
24 |
Issue |
2 |
Pages |
139-152 |
| Keywords |
Bachelor male; Band; Density; Habitat use; Home range; Management proposals; Micro-climate; Vegetation monitoring; habitat use; home range; mammal; social structure; spatial distribution; New Zealand; Equus caballus |
| Abstract |
We measured horse density, social structure, habitat use, home ranges and altitudinal micro-climates in the south-western Kaimanawa ranges east of Waiouru, New Zealand. Horse density in the Auahitotara ecological sector averaged 3.6 horses.km-2 and ranged from 0.9 to 5.2 horses.km-2 within different zones. The population's social structure was like that of other feral horse populations with an even adult sex ratio, year round breeding groups (bands) with stable adult membership consisting of 1 to 11 mares, 1 to 4 stallions, and their predispersal offspring, and bachelor groups with unstable membership. Bands and bachelor males were loyal to undefended home ranges with central core use areas. Band home range sizes varied positively with adult band size. Home ranges overlapped entirely with other home ranges. Horses were more likely to occupy north facing aspects, short tussock vegetation and flush zones and avoid high altitudes, southern aspects, steeper slopes, bare ground and forest remnants. Horses were more likely to be on north facing aspects, steeper slopes, in exotic and red tussock grasslands and flush zones during winter and at lower altitudes and on gentler slopes in spring and summer. Seasonal shifts by bands to river basin and stream valley floors in spring and higher altitudes in autumn and winter are attributed to the beginning of foaling and mating in spring and formation of frost inversion layers in winter. Given horse habitat selectivity and the presence of other ungulate herbivores, results from present exclosures are likely to exaggerate the size of horse impacts on range vegetation. Proposals to manage the population by relocation and confinement are likely to modify current social structure and range use behaviour and may lead to the need for more intensive management in the longer term. |
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Ecology Group, Institute of Natural Resources, Massey University, Private Bag 11-222, Palmerston North, New Zealand |
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01106465 (Issn) |
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Cited By (since 1996): 12; Export Date: 21 April 2007; Source: Scopus; Language of Original Document: English; Correspondence Address: Linklater, W.L.; Ecology Group; Institute of Natural Resources; Massey University; Private Bag 11-222 Palmerston North, New Zealand; email: wlinklater@hotmail.com |
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refbase @ user @ |
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793 |
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