Relation of Light to Bird Migration and Developmental Changes

Rowan, William

doi:10.1038/115494b0

Cited by 285 publications

(59 citation statements)

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“…Indeed, the activity of steroid-sensitive circuits (first section above), brain steroidogenesis (next section), and processes related to neural plasticity (second section below) are all seasonally regulated. Although steady advances in our understanding of the environmental regulation of avian behavior and physiology have occurred since pioneering work in the 1920s (Rowan, 1925), recent progress has been particularly remarkable.…”

Section: Environmental Effects On Avian Brain and Behavior: Tractabilmentioning

confidence: 99%

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Goodson

Saldanha

Hahn

et al. 2005

Hormones and Behavior

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Ever since investigations in the field of behavioral endocrinology were hatched with experiments on roosters, birds have provided original insights into issues of fundamental importance for all vertebrate groups. Here we focus on more recent advances that continue this tradition, including 1) environmental regulation of neuroendocrine and behavioral systems, 2) steroidogenic enzyme functions that are related to intracrine processes and de novo production of neurosteroids, and 3) hormonal regulation of neuroplasticity. We also review recent findings on the anatomical and functional organization of steroid-sensitive circuits in the basal forebrain and midbrain. A burgeoning body of data now demonstrates that these circuits comprise an evolutionarily conserved network, thus numerous novel insights obtained from birds can be used (in a relatively straightforward manner) to generate predictions for other taxa as well. We close by using birdsong as an example that links these areas together, thereby highlighting the exceptional opportunities that birds offer for integrative studies of behavioral neuroendocrinology, and behavioral biology in general. Keywords aggression; reproduction; song; limbic system; vasotocin; photoperiod; neurosteroid; DHEA; aromatase; adult neurogenesis; estrogen; testosterone; thyroxin; hypothalamus; hippocampus; HVC; septum; GnRH; SCN; season; neuroplasticity Birds offer excellent opportunities for behavioral and neuroendocrine experiments in both the field and the laboratory, and studies conducted at this interface have historically placed avian models on the cutting edge of research (Konishi et al., 1989; also see Wingfield, this issue). Indeed, wild birds offer a combination of accessibility (being diurnal and terrestrial) and diversity (social and ecological) that makes them invaluable models for studying mechanistic and evolutionary questions that are not as tractable in other vertebrate groups. This diversity can be studied within the context of neural and endocrine systems that share many features with those of other taxa (thereby increasing the general relevance of avian studies) (Goodson, 2005), although these features are often more pronounced in birds. Such examples include exceptionally robust and widespread neural aromatase activity, and adult neurogenesis in the forebrain, both of which are considered further below (also see Ball and Balthazart, 2004;

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Section: Environmental Effects On Avian Brain and Behavior: Tractabilmentioning

confidence: 99%

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Goodson

Saldanha

Hahn

et al. 2005

Hormones and Behavior

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“…The central tenant that day length plays a key role in regulating timing of breeding has been widely accepted for almost 100 years since the pioneering work of Rowan [95,96], and his investigations have been very influential in driving neuroendocrinological research on the control of seasonality. Photoperiod is still considered as the major environmental cue containing long-term predictive information about the optimal period for initiating and terminating breeding [29,100,133], and is therefore one of the most studied topics in avian physiology.…”

Section: Literature Investigationmentioning

confidence: 99%

Avian ecologists and physiologists have different sexual preferences

Samuel

2012

General and Comparative Endocrinology

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Seasonal timing is studied by ecologists and physiologists alike and it is now widely recognized that further integration of these fields is needed for a full understanding of phenology. This is especially true in the light of the impact of global climate change on living organisms. In studies of avian reproduction, one obstacle to this integration is that ecologists and physiologists do not allocate their research efforts equally to males and females. The physiological orchestration of breeding stages has been studied almost exclusively in males, while in avian ecology and evolutionary biology females are more often considered. This sex bias has severe implications: sexes differ in the way they use external cues to organize their life cycles, but often cue in on each other's physiology and behavior. The simultaneous investigation of both males and females within single studies is thus essential. In this review, I begin by illustrating the sex-bias in studies and attempt to explain its origin. I then provide a number of examples in which focusing on a single sex would have resulted in misleading conclusions. Finally, I review some classical studies of female reproductive physiology that have promoted and developed research on the "forgotten-sex". AbstractSeasonal timing is studied by ecologists and physiologists alike and it is now widely recognized that further integration of these fields is needed for a full understanding of phenology. This is especially true in the light of the impact of global climate change on living organisms. In studies of avian reproduction, one obstacle to this integration is that ecologists and physiologists do not allocate their research efforts equally to males and females. The physiological orchestration of breeding stages has been studied almost exclusively in males, while in avian ecology and evolutionary biology females are more often considered. This sex bias has severe implications: sexes differ in the way they use external cues to organize their life cycles, but often cue in on each other's physiology and behavior. The simultaneous investigation of both males and females within single studies is thus essential. In this review, Ibegin by illustrating the sex-bias in studies and attempt to explain its origin. I then provide a number of examples in which focusing on a single sex would have resulted in misleading conclusions. Finally, I review some classical studies of female reproductive physiology that have promoted and developed research on the "forgotten-sex".

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“…In birds, the mechanisms involved in the processes of photoperiodic time measurement and of light transmission to the brain remains, in part, unexplained. Since the early observations of Rowan (1925), several hypotheses have been proposed to describe the precise and highly repeatable mechanism by which avian species perceive and measure the duration and variations of photoperiod to regulate their reproductive season. While extensive research has demonstrated that photoperiodic time measurement in mammals and birds is perceived through the circadian system (Benoît, 1935), indications now exist in birds that the median basal hypothalamus contains several major components involved in a specific response to photoperiod (Ball and Balthazart, 2003).…”

Section: Seasonality Of Reproductive Activity Is An Old Story First Smentioning

confidence: 99%

Seasonality of reproduction and production in farm fishes, birds and mammals

Chemineau

Malpaux

Brillard

et al. 2007

Animal

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A very large majority of farm animals express seasonal variations in their production traits, thus inducing seasonal availability of fresh derived animal products (meat, milk, cheese and eggs). This pattern is in part the consequence of the farmer's objective to market his products in the most economically favourable period. It may also be imposed by the season-dependent access to feed resources, as in ruminants, or by the specific requirements derived from adaptation to environmental conditions such as water temperature in fish. But seasonal variations in animal products are also the consequence of constraints resulting from the occurrence of a more or less marked seasonal reproductive season in most farm animal species including fish, poultry and mammals. Like their wild counterparts, at mid and high latitudes, most farm animals normally give birth at the end of winter-early spring, the most favourable period for the progeny to survive and thus promote the next generation. As a consequence, most species show seasonal variations in their ovulation frequency (mammals and fish: presence or absence of ovulation; birds: variations or suppression of laying rates), spermatogenic activity (from moderate to complete absence of sperm production), gamete quality (variations in fertilisation rates and embryo survival), and also sexual behaviour. Among species of interest for animal production, fishes and birds are generally considered as more directly sensitive to external factors (mainly temperature in fish, photoperiod in birds). In all species, it is therefore advisable that artificial photoperiodic treatments consisting of extra-light during natural short days (in chickens, turkeys, guinea fowl, sheep and goats) or melatonin during long days (in goats, sheep) be extensively used to either adjust the breeding season to animal producer needs and/or to completely overcome seasonal variations of sperm production in artificial insemination centres (mammals) and breeder flock operations (poultry, fish farming). Pure light treatments (without melatonin), especially when applied in open barns, could be considered as non invasive ones which fully respect animal welfare.Keywords: birds, fish, mammals, photoperiod, reproduction, seasonality Seasonal variations in marketed products of animal originSeasonal availability of animal products for human consumption has been common long before domestication. In farm animals this pattern has led to the development of breeding stocks aimed at providing animal products all the year round. Despite the fact that domestication processes, which reduce the dependency of farm animals on natural conditions, generally reduce seasonality of reproduction compared with their wild counterparts, a majority of animal-derived products remain accessible only seasonally. This is a consequence of the cycles of reproduction and production which are themselves seasonal as domestic stock have inherited the characteristics of the natural populations from which they originate (see below and Ortavant et al. (198...

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Relation of Light to Bird Migration and Developmental Changes

Cited by 285 publications

References 1 publication

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Recent advances in behavioral neuroendocrinology: Insights from studies on birds

Avian ecologists and physiologists have different sexual preferences

Seasonality of reproduction and production in farm fishes, birds and mammals

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