<i>Zugunruhe</i>of migratory and non‐migratory birds in a circannual context

Helm, Barbara

doi:10.1111/j.2006.0908-8857.03947.x

Cited by 41 publications

(59 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zugunruhe in captive birds shows distinct responsiveness to photoperiod, typically in accordance with calendar responses noted in the wild (Gwinner 1968(Gwinner , 1971(Gwinner , 1972a(Gwinner ,b, 1988. Thus, in various species, including sylviid warblers and stonechats, captive birds initiate fall migratory restlessness at similar day length conditions as free-living conspecifics (Gwinner, Helm et al 2005;Helm 2006). Circannual rhythms and programmed responses to photoperiod have been found for many other migration-related traits, including migratory direction Berthold 2001;Mouritsen 2003).…”

mentioning

confidence: 99%

“…In general, circannual rhythms tend to be relatively weakly self-sustained, i.e. they typically show considerable inter-individual variation and can be entrained to a wide range of period lengths Goldmann et al 2004;Helm 2006). Further, they are usually expressed only under a relatively narrow range of permissive day length conditions Lincoln et al 2006).…”

mentioning

confidence: 99%

“…In contrast, stonechats from higher latitudes show repeated but irregular bouts of seasonal behaviours under constant conditions in the laboratory (Gwinner 1991(Gwinner , 1996aHelm 2006). Circannual rhythms of zugunruhe in strongly migratory species, such as the willow warbler, persist for many cycles without major damping or loss of precision, while cycles of the sibling species, the chiffchaff (Phylloscopus collybita), a shorter-distance migrant, show greater inter-individual variability and a stronger tendency to damp (Gwinner 1967(Gwinner , 1972a.…”

mentioning

confidence: 99%

“…(a) Interactions of circannual rhythms with environmental cues Circannual rhythms need to function in interaction with the environment and may be best understood as 'seasonally changing dispositions to respond to environmental cues' (Gwinner 1999;Helm 2006). In free-living animals, circannual rhythms, like circadian rhythms, are normally entrained to temporal information provided by the environment ( Loudon 1994;Gwinner 2003;Newton 2007; but see, e.g.…”

mentioning

confidence: 99%

“…The implicit rationale is that endogenous clocks help animals to keep time in the wild (e.g. Aschoff 1958;DeCoursey 2004;Roenneberg et al 2005;Helm 2006;Menaker 2006).…”

mentioning

confidence: 99%

See 4 more Smart Citations

Avian circannual clocks: adaptive significance and possible involvement of energy turnover in their proximate control

Wikelski

Martin

Scheuerlein

et al. 2007

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

Endogenous circannual clocks are found in many long-lived organisms, but are best studied in mammal and bird species. Circannual clocks are synchronized with the environment by changes in photoperiod, light intensity and possibly temperature and seasonal rainfall patterns. Annual timing mechanisms are presumed to have important ultimate functions in seasonally regulating reproduction, moult, hibernation, migration, body weight and fat deposition/stores. Birds that live in habitats where environmental cues such as photoperiod are poor predictors of seasons (e.g. equatorial residents, migrants to equatorial/tropical latitudes) rely more on their endogenous clocks than birds living in environments that show a tight correlation between photoperiod and seasonal events. Such population-specific/interspecific variation in reliance on endogenous clocks may indicate that annual timing mechanisms are adaptive. However, despite the apparent adaptive importance of circannual clocks, (i) what specific adaptive value they have in the wild and (ii) how they function are still largely untested. Whereas circadian clocks are hypothesized to be generated by molecular feedback loops, it has been suggested that circannual clocks are either based upon (i) a de-multiplication ('counting') of circadian days, (ii) a sequence of interdependent physiological states, or (iii) one or more endogenous oscillators, similar to circadian rhythms. We tested the de-multiplication of days (i) versus endogenous regulation hypotheses (ii) and (iii) in captive male and female house sparrows (Passer domesticus). We assessed the period of reproductive (testicular and follicular) cycles in four groups of birds kept either under photoperiods of LD 12 L : 12 D (period length: 24 h), 13.5 L : 13.5 D (27 h), 10.5 L : 10.5 D (23 h) or 12 D : 8 L : 3 D : 1 L (24-h skeleton photoperiod), respectively, for 15 months. Contrary to predictions from the de-multiplication hypothesis, individuals experiencing 27-h days did not differ (i.e. did not have longer) annual reproductive rhythms than individuals from the 21-or 24-h day groups. However, in line with predictions from endogenous regulation, birds in the skeleton group had significantly longer circannual period lengths than all other groups. Birds exposed to skeleton photoperiods experienced fewer light hours per year than all other groups (3285 versus 4380) and had a lower daily energy expenditure, as tested during one point of the annual cycle using respirometry. Although our results are tantalizing, they are still preliminary as birds were only studied over a period of 15 months. Nevertheless, the present data fail to support a 'counting of circadian days' and instead support hypotheses proposing whole-organism processes as the mechanistic basis for circannual rhythms. We propose a novel energy turnover hypothesis which predicts a dependence of the speed of the circannual clock on the overall energy expenditure of an organism.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The implicit rationale is that endogenous clocks help animals to keep time in the wild (e.g. Aschoff 1958;DeCoursey 2004;Roenneberg et al 2005;Helm 2006;Menaker 2006).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Avian circannual clocks: adaptive significance and possible involvement of energy turnover in their proximate control

Wikelski

Martin

Scheuerlein

et al. 2007

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

show abstract

Photoperiodic regulation of avian physiology: From external coincidence to seasonal reproduction

2022

View full text Add to dashboard Cite

Seasonal cycles of environmental cues generate variation in the timing of life‐history transition events across taxa. It is through the entrainment of internal, endogenous rhythms of organisms to these external, exogenous rhythms in environment, such as cycling temperature and daylight, by which organisms can regulate and time life history transitions. Here, we review the current understanding of how photoperiod both stimulates and terminates seasonal reproduction in birds. The review describes the role of external coincidence timing, the process by which photoperiod is proposed to stimulate reproductive development. Then, the molecular basis of light detection and the photoperiodic regulation of neuroendocrine timing of seasonal reproduction in birds is presented. Current data indicates that vertebrate ancient opsin is the predominant photoreceptor for light detection by the hypothalamus, compared to neuropsin and rhodopsin. The review then connects light detection to well‐characterized hypothalamic and pituitary gland molecules involved in the photoperiodic regulation of reproduction. In birds, Gonadotropin‐releasing hormone synthesis and release are controlled by photoperiodic cues via thyrotropin‐stimulating hormone‐β (TSHβ) independent and dependent pathways, respectively. The review then highlights the role of D‐box and E‐box binding motifs in the promoter regions of photoperiodic genes, in particular Eyes‐absent 3, as the key link between circadian clock function and photoperiodic time measurement. Based on the available evidence, the review proposes that at least two molecular programs form the basis for external coincidence timing in birds: photoperiodic responsiveness by TSHβ pathways and endogenous internal timing by gonadotropin synthesis.

show abstract