| Records |
| Author |
Linklater, W.L.; Cameron, E.Z.; Stafford, K.J.; Austin, T. |
| Title |
Chemical immobilisation and temporary confinement of two Kaimanawa feral stallions |
Type |
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| Year |
1998 |
Publication |
New Zealand veterinary journal |
Abbreviated Journal |
N Z Vet J |
| Volume |
46 |
Issue |
3 |
Pages |
117-118 |
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| Abstract |
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| Language |
English |
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Edition |
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ISSN  |
0048-0169 |
ISBN |
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| Notes |
PMID:16032032 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
412 |
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| Author |
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. |
| Address |
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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| Notes |
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 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
793 |
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| Author |
Cameron, E.Z. |
| Title |
Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism |
Type |
Journal Article |
| Year |
2004 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
| Volume |
271 |
Issue |
1549 |
Pages |
1723-1728 |
| Keywords |
Age Factors; Animals; Body Constitution; *Evolution; Female; Glucose/metabolism/physiology; Litter Size; Male; Mammals/*physiology; *Models, Biological; Reproduction/physiology; Seasons; Sex Factors; *Sex Ratio; Time Factors |
| Abstract |
Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios. |
| Address |
Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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English |
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Edition |
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| ISSN |
0962-8452 |
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| Notes |
PMID:15306293 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
413 |
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| Author |
Cameron, E.Z.; du Toit, J.T. |
| Title |
Winning by a neck: tall giraffes avoid competing with shorter browsers |
Type |
Journal Article |
| Year |
2007 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
| Volume |
169 |
Issue |
1 |
Pages |
130-135 |
| Keywords |
Acacia/growth & development; Animals; Feeding Behavior/*physiology; Neck/*anatomy & histology; Plant Leaves/growth & development; Ruminants/*anatomy & histology/*physiology; South Africa |
| Abstract |
With their vertically elongated body form, giraffes generally feed above the level of other browsers within the savanna browsing guild, despite having access to foliage at lower levels. They ingest more leaf mass per bite when foraging high in the tree, perhaps because smaller, more selective browsers deplete shoots at lower levels or because trees differentially allocate resources to promote shoot growth in the upper canopy. We erected exclosures around individual Acacia nigrescens trees in the greater Kruger ecosystem, South Africa. After a complete growing season, we found no differences in leaf biomass per shoot across height zones in excluded trees but significant differences in control trees. We conclude that giraffes preferentially browse at high levels in the canopy to avoid competition with smaller browsers. Our findings are analogous with those from studies of grazing guilds and demonstrate that resource partitioning can be driven by competition when smaller foragers displace larger foragers from shared resources. This provides the first experimental support for the classic evolutionary hypothesis that vertical elongation of the giraffe body is an outcome of competition within the browsing ungulate guild. |
| Address |
Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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English |
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Edition |
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| ISSN |
1537-5323 |
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| Notes |
PMID:17206591 |
Approved |
no |
| Call Number |
refbase @ user @ |
Serial |
410 |
| Permanent link to this record |
