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Author |
Cameron, E.Z.; du Toit, J.T. |
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Title |
Winning by a neck: tall giraffes avoid competing with shorter browsers |
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Journal Article |
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Year |
2007 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
169 |
Issue |
1 |
Pages |
130-135 |
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Keywords |
Acacia/growth & development; Animals; Feeding Behavior/*physiology; Neck/*anatomy & histology; Plant Leaves/growth & development; Ruminants/*anatomy & histology/*physiology; South Africa |
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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. |
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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1537-5323 |
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PMID:17206591 |
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no |
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refbase @ user @ |
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410 |
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Author |
Hampton, R.R.; Shettleworth, S.J. |
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Title |
Hippocampus and memory in a food-storing and in a nonstoring bird species |
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Journal Article |
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Year |
1996 |
Publication |
Behavioral neuroscience |
Abbreviated Journal |
Behav Neurosci |
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Volume |
110 |
Issue |
5 |
Pages |
946-964 |
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Keywords |
Animals; Appetitive Behavior/*physiology; Attention/physiology; Birds/*physiology; Brain Mapping; Feeding Behavior/*physiology; Mental Recall/*physiology; Organ Size/physiology; Orientation/*physiology; Retention (Psychology)/physiology; Species Specificity |
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Abstract |
Food-storing birds maintain in memory a large and constantly changing catalog of the locations of stored food. The hippocampus of food-storing black-capped chickadees (Parus atricapillus) is proportionally larger than that of nonstoring dark-eyed juncos (Junco hyemalis). Chickadees perform better than do juncos in an operant test of spatial non-matching-to-sample (SNMTS), and chickadees are more resistant to interference in this paradigm. Hippocampal lesions attenuate performance in SNMTS and increase interference. In tests of continuous spatial alternation (CSA), juncos perform better than chickadees. CSA performance also declines following hippocampal lesions. By itself, sensitivity of a given task to hippocampal damage does not predict the direction of memory differences between storing and nonstoring species. |
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Department of Psychology, University of Toronto, Ontario, Canada. robert@ln.nimh.nih.gov |
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0735-7044 |
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PMID:8918998 |
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refbase @ user @ |
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375 |
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Author |
Shettleworth, S.J. |
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Title |
Memory and hippocampal specialization in food-storing birds: challenges for research on comparative cognition |
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Journal Article |
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Year |
2003 |
Publication |
Brain, behavior and evolution |
Abbreviated Journal |
Brain Behav Evol |
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Volume |
62 |
Issue |
2 |
Pages |
108-116 |
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Keywords |
Animals; Birds/*physiology; Cognition/*physiology; Color Perception/physiology; Feeding Behavior/*physiology; Hippocampus/*physiology; Memory/*physiology; Species Specificity |
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Abstract |
The three-way association among food-storing behavior, spatial memory, and hippocampal enlargement in some species of birds is widely cited as an example of a new 'cognitive ecology' or 'neuroecology.' Whether this relationship is as strong as it first appears and whether it might be evidence for an adaptive specialization of memory and hippocampus in food-storers have recently been the subject of some controversy [Bolhuis and Macphail, 2001; Macphail and Bolhuis, 2001]. These critiques are based on misconceptions about the nature of adaptive specializations in cognition, misconceptions about the uniformity of results to be expected from applying the comparative method to data from a wide range of species, and a narrow view of what kinds of cognitive adaptations are theoretically interesting. New analyses of why food-storers (black-capped chickadees, Poecile Atricapilla) respond preferentially to spatial over color cues when both are relevant in a memory task show that this reflects a relative superiority of spatial memory as compared to memory for color rather than exceptional spatial attention or spatial discrimination ability. New studies of chickadees from more or less harsh winter climates also support the adaptive specialization hypothesis and suggest that within-species comparisons may be especially valuable for unraveling details of the relationships among ecology, memory, and brain in food-storing species. |
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Department of Psychology, University of Toronto, Toronto, Ont., M5S 3G3, Canada. shettle@psych.utoronto.ca |
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0006-8977 |
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PMID:12937349 |
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no |
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refbase @ user @ |
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367 |
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Author |
Shettleworth, S.J. |
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Title |
Animal behaviour: planning for breakfast |
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Journal Article |
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Year |
2007 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
445 |
Issue |
7130 |
Pages |
825-826 |
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Keywords |
Animals; Feeding Behavior/*physiology; *Food; Haplorhini/physiology; Memory/physiology; Songbirds/*physiology; Thinking/*physiology |
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1476-4687 |
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Notes |
PMID:17314961 |
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no |
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refbase @ user @ |
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356 |
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Author |
Dixon, G.; Green, L.E.; Nicol, C.J. |
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Title |
Effect of diet change on the behavior of chicks of an egg-laying strain |
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Journal Article |
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Year |
2006 |
Publication |
Journal of applied animal welfare science : JAAWS |
Abbreviated Journal |
J Appl Anim Welf Sci |
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Volume |
9 |
Issue |
1 |
Pages |
41-58 |
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Keywords |
*Animal Feed; *Animal Nutrition Physiology; Animals; Behavior, Animal/*physiology; Chickens/*physiology; Crowding; Feeding Behavior/*physiology; Female; Food Preferences/physiology; Oviposition; Random Allocation; Taste |
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Abstract |
Injurious pecking has serious welfare consequences in flocks of hens kept for egg laying, especially when loose-housed. Frequent diet change is a significant risk for injurious pecking; how the mechanics of diet change influence pecking behavior is unknown. This study investigated the effect of diet change on the behavior of chicks from a laying strain. The study included a 3-week familiarity phase: 18 chick pairs received unflavored feed (Experiment 1); 18 pairs received orange oil-flavored (Experiment 2). All chicks participated in a dietary preference test (P); a diet change (DC); or a control group (C), 6 scenarios. All P chicks preferred unflavored feed. In Experiment 1, DC involved change from unflavored to orange-flavored; Experiment 2, orange- flavored to unflavored. Compared with controls, Experiment 2 DC chicks exhibited few behavioral differences; Experiment 1 DC chicks exhibited increased behavioral event rates on Days 1 and 7. They pecked significantly longer at their environment; by Day 7, they showed significantly more beak activity. There was little evidence of dietary neophobia. Change from more preferred to less preferred feed led to increased activity and redirected pecking behavior. |
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School of Veterinary Science, University of Bristol, England |
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ISSN |
1088-8705 |
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Notes |
PMID:16649950 |
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no |
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Call Number |
refbase @ user @ |
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64 |
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Author |
Houpt, K.A. |
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Title |
Ingestive behavior |
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Journal Article |
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Year |
1990 |
Publication |
The Veterinary clinics of North America. Equine practice |
Abbreviated Journal |
Vet Clin North Am Equine Pract |
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Volume |
6 |
Issue |
2 |
Pages |
319-337 |
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Keywords |
Animals; Eating/*physiology; Feeding Behavior/*physiology; Horses/*physiology |
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Abstract |
In summary, horses spend 60% or more of their time eating when grazing or when feed is available free choice. Grasses are their preferred food, but they supplement the grass with herbs and woody plants. Sweetened mixtures of oats and corn are the most preferred concentrate. Horses can increase or decrease the time spent eating and amount eaten to maintain caloric intake. Their intake is stimulated by drugs such as diazepam and by the presence of other horses. Horses stop eating when gastric osmolality increases; increases in plasma osmolality, protein, and glucose accompany digestion. Foals eat several times an hour and begin sampling solid food at the same time that their dam is eating. Several areas of particular importance to the equine industry have not been investigated. These areas include the effect of exercise on short- and long-term food intake and the influence of reproductive state on the feeding of mares. |
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Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca |
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ISSN |
0749-0739 |
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PMID:2202495 |
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Call Number |
refbase @ user @ |
Serial |
42 |
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