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Differences in phenological responses to climate change among species can desynchronise ecological interactions and thereby threaten ecosystem function. To assess these threats, we must quantify the relative impact of climate change on species at different trophic levels. Here, we apply a Climate Sensitivity Profile approach to 10,003 terrestrial and aquatic phenological data sets, spatially matched to temperature and precipitation data, to quantify variation in climate sensitivity. The direction, magnitude and timing of climate sensitivity varied markedly among organisms within taxonomic and trophic groups. Despite this variability, we detected systematic variation in the direction and magnitude of phenological climate sensitivity. Secondary consumers showed consistently lower climate sensitivity than other groups. We used mid-century climate change projections to estimate that the timing of phenological events could change more for primary consumers than for species in other trophic levels (6.2 versus 2.5-2.9 days earlier on average), with substantial taxonomic variation (1.1-14.8 days earlier on average)., Numerous long-term ecological changes have been attributed to climate change (1). Shifts in the seasonal timing of recurring biological events such as reproduction and migration (that is, phenological changes) have [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.03.017 Byline: David I. Leech, Louise V. Rowe, Ian R. Hartley Abstract: Parents should allocate parental investment in relation to the expected reproductive value of their offspring. We used a cross-fostering experiment to see whether factors influencing offspring reproductive value (brood size, nestling sex, age or paternity) were related to parental investment in nest defence in the blue tit, Cyanistes caeruleus. Although brood size and the incidence of extrapair paternity did not influence the nest defence behaviour of parents, we found a significant difference in the way male and female parents responded to the experimental change in sex ratio of the brood; the nest defence response of males was faster at nests with an increased proportion of sons, but the response of females was unrelated to changes in brood sex ratio. Furthermore, there was no relation between the original sex ratio of the brood, before manipulation, and the nest defence response of the male, indicating that paternal investment in this behaviour was a direct response to the manipulated brood sex ratio. Author Affiliation: (a) Department of Biological Sciences, Lancaster University, U.K. (a ) British Trust for Ornithology, Thetford, U.K. Article History: Received 27 January 2005; Revised 6 March 2005; Accepted 20 March 2006 Article Note: (miscellaneous) MS. number: 8444R

Abstract: A consequence of climate change has been an advance in the timing of seasonal events. Differences in the rate of advance between trophic levels may result in predators becoming mismatched with prey availability, reducing fitness and potentially driving population declines. Such “trophic asynchrony” is hypothesized to have contributed to recent population declines of long‐distance migratory birds in particular. Using spatially extensive survey data from 1983 to 2010 to estimate variation in spring phenology from 280 plant and insect species and the egg‐laying phenology of 21 British songbird species, we explored the effects of trophic asynchrony on avian population trends and potential underlying demographic mechanisms. Species which advanced their laying dates least over the last three decades, and were therefore at greatest risk of asynchrony, exhibited the most negative population trends. We expressed asynchrony as the annual variation in bird phenology relative to spring phenology, and related asynchrony to annual avian productivity. In warmer springs, birds were more asynchronous, but productivity was only marginally reduced; long‐distance migrants, short‐distance migrants and resident bird species all exhibited effects of similar magnitude. Long‐term population, but not productivity, declines were greatest among those species whose annual productivity was most greatly reduced by asynchrony. This suggests that population change is not mechanistically driven by the negative effects of asynchrony on productivity. The apparent effects of asynchrony on population trends are therefore either more likely to be strongly expressed via other demographic pathways, or alternatively, are a surrogate for species' sensitivity to other environmental pressures which are the ultimate cause of decline. [ABSTRACT FROM AUTHOR]

Establishing the cues or constraints that influence avian timing of breeding is the key to accurate prediction of future phenology. This study aims to identify the aspects of the environment that predict the timing of two measures of breeding phenology (nest initiation and egg laying date) in an insectivorous woodland passerine, the blue tit (Cyanistes caeruleus). We analyse data collected from a 220 km, 40-site transect over 3 years and consider spring temperatures, tree leafing phenology, invertebrate availability and photoperiod as predictors of breeding phenology. We find that mean night-time temperature in early spring is the strongest predictor of both nest initiation and lay date and suggest this finding is most consistent with temperature acting as a constraint on breeding activity. Birch budburst phenology significantly predicts lay date additionally to temperature, either as a direct cue or indirectly via a correlated variable. We use cross-validation to show that our model accurately predicts lay date in two further years and find that similar variables predict lay date well across the UK national nest record scheme. This work refines our understanding of the principal factors influencing the timing of tit reproductive phenology and suggests that temperature may have both a direct and indirect effect.