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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
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0962-8452	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15306293			Approved	no
	Call Number	refbase @ user @			Serial	413
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	Author	Packer, C; Heinsohn, R.
	Title	Response:Lioness leadership			Type	Journal Article
	Year	1996	Publication	Science (New York, N.Y.)	Abbreviated Journal	Science
	Volume	271	Issue	5253	Pages	1215-1216
	Keywords	Animals; Behavior; Animal; Cooperative Behavior; Female; Lions/psychology; Territoriality
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0036-8075	ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @ Jahn1996			Serial	2072
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	Author	Gary C. Jahn; Craig Packer,Robert Heinsohn
	Title	Lioness leadership			Type	Journal Article
	Year	1996	Publication	Science (New York, N.Y.)	Abbreviated Journal	Science
	Volume	271	Issue	5253	Pages	1216-1219
	Keywords	Animals; Behavior; Animal; Cooperative Behavior; Female; Lions/psychology; Territoriality
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0036-8075	ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @ Jahn1996			Serial	2073
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	Author	Hunt, G.R.; Gray, R.D.
	Title	The crafting of hook tools by wild New Caledonian crows			Type	Journal Article
	Year	2004	Publication	Proceedings of the Royal Society B: Biological Sciences	Abbreviated Journal	Proc. Roy. Soc. Lond. B Biol. Sci.
	Volume	271	Issue		Pages	S88-S90
	Keywords
	Abstract	The 'crafting' of tools involves (i) selection of appropriate raw material, (ii) preparatory trimming and (iii) fine, three-dimensional sculpting. Its evolution is technologically important because it allows the open-ended development of tools. New Caledonian crows manufacture an impressive range of stick and leaf tools. We previously reported that their toolkit included hooked implements made from leafy twigs, although their manufacture had never been closely observed. We describe the manufacture of 10 hooked-twig tools by an adult crow and its dependent juvenile. To make all 10 tools, the crows carried out a relatively invariant three-step sequence of complex manipulations that involved (i) the selection of raw material, (ii) trimming and (iii) a lengthy sculpting of the hook. Hooked-twig manufacture contrasts with the lack of sculpting in the making of wooden tools by other non-humans such as chimpanzees and woodpecker finches. This fine, three-stage crafting process removes another alleged difference between humans and other animals.
	Address
	Corporate Author				Thesis
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	Notes				Approved	no
	Call Number	refbase @ user @			Serial	3526
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	Author	Griffiths,S. W.; Brockmark, S.; Höjesjö,J.; Johnsson,J. I.
	Title	Coping with divided attention: the advantage of familiarity			Type	Journal Article
	Year	2004	Publication	Proceedings of the Royal Society B: Biological Sciences	Abbreviated Journal	Proc. Roy. Soc. Lond. B Biol. Sci.
	Volume	271	Issue	1540	Pages	695-699
	Keywords
	Abstract	The ability of an animal to perform a task successfully is limited by the amount of attention being simultaneously focused on other activities. One way in which individuals might reduce the cost of divided attention is by preferentially focusing on the most beneficial tasks. In territorial animals where aggression is lower among familiar individuals, the decision to associate preferentially with familiar conspecifics may therefore confer advantages by allowing attention to be switched from aggression to predator vigilance and feeding. Wild juvenile brown trout were used to test the prediction that familiar fishes respond more quickly than unfamiliar fishes to a simulated predator attack. Our results confirm this prediction by demonstrating that familiar trout respond 14% faster than unfamiliar individuals to a predator attack. The results also show that familiar fishes consume a greater number of food items, foraging at more than twice the rate of unfamiliar conspecifics. To the best of our knowledge, these results provide the first evidence that familiarity–biased association confers advantages through the immediate fitness benefits afforded by faster predator–evasion responses and the long–term benefits provided by increased feeding opportunities.
	Address
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	Notes	10.1098/rspb.2003.2648			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5007
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	Author	Bugnyar, T.; Stöwe, M.; Heinrich, B.
	Title	*Ravens, Corvus corax, follow gaze direction of humans around obstacles*			Type	Journal Article
	Year	2004	Publication	Proceedings of the Royal Society B: Biological Sciences	Abbreviated Journal	Proc. Roy. Soc. Lond. B Biol. Sci.
	Volume	271	Issue	1546	Pages	1331-1336
	Keywords
	Abstract	The ability to follow gaze (i.e. head and eye direction) has recently been shown for social mammals, particularly primates. In most studies, individuals could use gaze direction as a behavioural cue without understanding that the view of others may be different from their own. Here, we show that hand–raised ravens not only visually co–orient with the look–ups of a human experimenter but also reposition themselves to follow the experimenter's gaze around a visual barrier. Birds were capable of visual co–orientation already as fledglings but consistently tracked gaze direction behind obstacles not before six months of age. These results raise the possibility that sub–adult and adult ravens can project a line of sight for the other person into the distance. To what extent ravens may attribute mental significance to the visual behaviour of others is discussed.
	Address
	Corporate Author				Thesis
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	Notes	10.1098/rspb.2004.2738			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5009
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	Author	Ghirlanda, S.; Vallortigara, G.
	Title	The evolution of brain lateralization: a game-theoretical analysis of population structure			Type	Journal Article
	Year	2004	Publication	Proceedings of the Royal Society of London. Series B: Biological Sciences	Abbreviated Journal
	Volume	271	Issue	1541	Pages	853-857
	Keywords
	Abstract	In recent years, it has become apparent that behavioural and brain lateralization at the population level is the rule rather than the exception among vertebrates. The study of these phenomena has so far been the province of neurology and neuropsychology. Here, we show how such research can be integrated with evolutionary biology to understand lateralization more fully. In particular, we address the fact that, within a species, left– and right–type individuals often occur in proportions different from one–half (e.g. hand use in humans). The traditional explanations offered for lateralization of brain function (that it may avoid unnecessary duplication of neural circuitry and reduce interference between functions) cannot account for this fact, because increased individual efficiency is unrelated to the alignment of lateralization at the population level. A further puzzle is that such an alignment may even be disadvantageous, as it makes individual behaviour more predictable to other organisms. Here, we show that alignment of the direction of behavioural asymmetries in a population can arise as an evolutionarily stable strategy when individual asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Brain and behavioural lateralization, as we know it in humans and other vertebrates, may have evolved under basically ‘social’ selection pressures.
	Address
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5345
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	Author	da Costa, A.P.; Leigh, A.E.; Man, M.-S.; Kendrick, K.M.
	Title	Face pictures reduce behavioural, autonomic, endocrine and neural indices of stress and fear in sheep			Type	Journal Article
	Year	2004	Publication	Proceedings of the Royal Society of London. Series B: Biological Sciences	Abbreviated Journal	Proc. R. Soc. Lond. B.
	Volume	271	Issue	1552	Pages	2077-2084
	Keywords
	Abstract	Faces are highly emotive stimuli and we find smiling or familiar faces both attractive and comforting, even as young babies. Do other species with sophisticated face recognition skills, such as sheep, also respond to the emotional significance of familiar faces? We report that when sheep experience social isolation, the sight of familiar sheep face pictures compared with those of goats or inverted triangles significantly reduces behavioural (activity and protest vocalizations), autonomic (heart rate) and endocrine (cortisol and adrenaline) indices of stress. They also increase mRNA expression of activity–dependent genes (c–fos and zif/268) in brain regions specialized for processing faces (temporal and medial frontal cortices and basolateral amygdala) and for emotional control (orbitofrontal and cingulate cortex), and reduce their expression in regions associated with stress responses (hypothalamic paraventricular nucleus) and fear (central and lateral amygdala). Effects on face recognition, emotional control and fear centres are restricted to the right brain hemisphere. Results provide evidence that face pictures may be useful for relieving stress caused by unavoidable social isolation in sheep, and possibly other animal species, including humans. The finding that sheep, like humans, appear to have a right brain hemisphere involvement in the control of negative emotional experiences also suggests that functional lateralization of brain emotion systems may be a general feature in mammals.
	Address
	Corporate Author				Thesis
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	5354
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	Author	Brilot, B.O.; Johnstone, R.A.
	Title	The limits to cost-free signalling of need between relatives			Type	Journal Article
	Year	2003	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	270	Issue	1519	Pages	1055-1060
	Keywords	Animal Communication; Animals; Birds/physiology; Models, Biological; Social Behavior
	Abstract	Theoretical models have demonstrated the possibility of stable cost-free signalling of need between relatives. The stability of these cost-free equilibria depends on the indirect fitness cost of cheating and deceiving a donor into giving away resources. We show that this stability is highly sensitive to the distribution of need among signallers and receivers. In particular, cost-free signalling is likely to prove stable only if there is very large variation in need (such that the least-needy individuals stand to gain much less than the most-needy individuals from additional resources). We discuss whether these conditions are likely to be found in altricial avian breeding systems--the most intensively studied instance of signalling of need between relatives. We suggest that cost-free signalling is more likely to prove stable and will provide parents with more information during the earlier phases of chick growth, when parents can more easily meet the demands of a brood (and chicks are more likely to reach satiation). Later, informative yet cost-free signalling is unlikely to persist.
	Address	Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. bob21@cam.ac.uk
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0962-8452	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12803895			Approved	no
	Call Number	refbase @ user @			Serial	558
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	Author	Drent, P.J.; van Oers, K.; van Noordwijk, A.J.
	Title	Realized heritability of personalities in the great tit (Parus major)			Type	Journal Article
	Year	2003	Publication	Proceedings. Biological sciences / The Royal Society	Abbreviated Journal	Proc Biol Sci
	Volume	270	Issue	1510	Pages	45-51
	Keywords	Aggression; Animals; Animals, Domestic; Animals, Wild; Behavior, Animal; Breeding; Exploratory Behavior; Female; Heredity; Male; Selection (Genetics); Songbirds/genetics/physiology; Variation (Genetics)
	Abstract	Behaviour under conditions of mild stress shows consistent patterns in all vertebrates: exploratory behaviour, boldness, aggressiveness covary in the same way. The existence of highly consistent individual variation in these behavioural strategies, also referred to as personalities or coping styles, allows us to measure the behaviour under standardized conditions on birds bred in captivity, link the standardized measurements to the behaviour under natural conditions and measure natural selection in the field. We have bred the great tit (Parus major), a classical model species for the study of behaviour under natural conditions, in captivity. Here, we report a realized heritability of 54 +/- 5% for early exploratory behaviour, based on four generations of bi-directional artificial selection. In addition to this, we measured hand-reared juveniles and their wild-caught parents in the laboratory. The heritability found in the mid-offspring-mid-parent regression was significantly different from zero. We have thus established the presence of considerable amounts of genetic variation for personality types in a wild bird.
	Address	Netherlands Institute of Ecology, PO Box 40, 6666 ZG Heteren, The Netherlands. drent@cto.nioo.knaw.nl
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0962-8452	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12590770			Approved	no
	Call Number	refbase @ user @			Serial	591
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