Decline in the frequency and benefits of multiple brooding in great tits as a consequence of a changing environment

Abstract

For multiple-brooded species, the number of reproductive events per year is a major determinant of an individual's fitness. Where multiple brooding is facultative, its occurrence is likely to change with environmental conditions, and, as a consequence, the current rates of environmental change could have substantial impacts on breeding patterns. Here we examine temporal population-level trends in the proportion of female great tits (Parus major) producing two clutches per year ('double brooding') in four long-term study populations in The Netherlands, and show that the proportion of females that double brood has declined in all populations, with the strongest decline taking place in the last 30 years of the study. For one of the populations, for which we have data on caterpillar abundance, we show that the probability that a female produces a second clutch was related to the timing of her first clutch relative to the peak in caterpillar abundance, and that the probability of double brooding declined over the study period. We further show that the number of recruits from the second clutch decreased significantly over the period in all populations. Our results indicate that adjustment to changing climatic conditions may involve shifts in life-history traits other than simply the timing of breeding.

Toward a synthetic understanding of the role of phenology in ecology and evolution

“…Phenology in ecology and evolution J. temperate-zone birds and other taxa are capable of double-brooding if there is time (Verhulst et al 1997 and references therein; Saino et al 2004), provided food resources are also sufficient (cf. Husby et al 2009). In short-lived species, warmer temperatures and longer growing seasons may allow additional generations per year (e.g.…”

Testing Mechanisms of Bergmann’s Rule: Phenotypic Decline but No Genetic Change in Body Size in Three Passerine Bird Populations

“…Unfortunately, information on beech crop index, date of caterpillar peak, and synchrony (the difference between the date of the caterpillar peak and the yearly mean laying date) was available only for the HV population from 1985 onward (see Visser et al 2006;Husby et al 2009), and thus we had to restrict our analysis to the HV population and the years 1985-2008. We included adult body mass (and tarsus length) as response variables in a linear mixed model, with the above environmental factors included as explanatory variables and individual identity as a random effect to account for repeated measures on the same individuals.…”

Individual quality and double-brooding in a highly synchronous songbird population

“…Numerous studies have suggested that the timing of breeding-laying date of the first clutch-is the most important factor determining the propensity for doublebrooding: The incidence of second clutches generally declines the later the first clutch is initiated (Geupel and DeSante 1990, Verboven et al 2001, Brinkhof et al 2002, Parejo and Danchin 2006, Husby et al 2009, O'Brien and Dawson 2013, Hoffmann et al 2015. A higher frequency of double-brooding among early-laying females could occur simply because these females then have more time to rear a second brood, or because their initially early laying date makes them less affected by seasonal declines in the quality of the rearing environment (e.g., the feeding of earlier second broods can still be relatively synchronous with the seasonal peak in food supply (date hypothesis); Verhulst 1996, Husby et al 2009).…”

“…In addition, the fitness consequences of double-brooding in adults (survival, future fecundity) as a result of increased reproductive effort are relatively poorly studied (but see Geupel and Desante 1990, Morton et al 2004, Nagy and Holmes 2005b, Husby et al 2009). Previous studies have suggested that double-brooding can be associated with lower survival (Bryant 1979, Brinkhof et al 2002 or no survival cost (Geupel and Desante 1990, Morton et al 2004, Nagy and Holmes 2005b, Husby et al 2009), but few studies have considered the effects on future fecundity, likely due to a combination of low return rates and the difficulty of repeatedly finding nests belonging to the same individuals.…”