The extended Moran effect and large‐scale synchronous fluctuations in the size of great tit and blue tit populations

Abstract

Summary1. Synchronous fluctuations of geographically separated populations are in general explained by the Moran effect, i.e. a common influence on the local population dynamics of environmental variables that are correlated in space. Empirical support for such a Moran effect has been difficult to provide, mainly due to problems separating out effects of local population dynamics, demographic stochasticity and dispersal that also influence the spatial scaling of population processes. Here we generalize the Moran effect by decomposing the spatial autocorrelation function for fluctuations in the size of great tit Parus major and blue tit Cyanistes caeruleus populations into components due to spatial correlations in the environmental noise, local differences in the strength of density regulation and the effects of demographic stochasticity. 2. Differences between localities in the strength of density dependence and nonlinearity in the density regulation had a small effect on population synchrony, whereas demographic stochasticity reduced the effects of the spatial correlation in environmental noise on the spatial correlations in population size by 21·7% and 23·3% in the great tit and blue tit, respectively. 3. Different environmental variables, such as beech mast and climate, induce a common environmental forcing on the dynamics of central European great and blue tit populations. This generates synchronous fluctuations in the size of populations located several hundred kilometres apart. 4. Although these environmental variables were autocorrelated over large areas, their contribution to the spatial synchrony in the population fluctuations differed, dependent on the spatial scaling of their effects on the local population dynamics. We also demonstrate that this effect can lead to the paradoxical result that a common environmental variable can induce spatial desynchronization of the population fluctuations.

Causes and Consequences of Intraspecific Variation in Nesting Behaviors: Insights from Blue Tits and Great Tits

“…Accordingly, both species have been used as model systems in studies examining a range of issues including nest site selection (Slagsvold, 1975), the role of nestbox design in determining reproductive parameters (Karlsson and Nilsson, 1977;Lambrechts et al, 2010;Møller et al, 2014a) and host-parasite interactions (Hebda et al, 2013). Meanwhile, other studies have examined temporal (Visser et al, 1998(Visser et al, , 2006 and spatial variation in their reproductive parameters (Visser et al, 2003;Møller et al, 2014b) and as large proportions of birds occupy nestboxes, then other studies have examined their population dynamics (Kluijver, 1951;Saether et al, 2007).…”

Climate Events Synchronize the Dynamics of a Resident Vertebrate Community in the High Arctic

“…More far-reaching consequences may be expected if such climate-enforced synchronization acts on the level of ecological communities (7,8). However, linking cross-species synchrony to common environmental drivers has proven difficult as variation among species in the form of density regulation and response to other environmental drivers often has a desynchronizing effect (9). Thus, observed synchrony usually results from trophic interactions, such as the cofluctuations among predators because of shared prey (3).…”

An evaluation of the synchronization in the dynamics of blue crab (Callinectes sapidus) populations in the western Atlantic

“…Aphid populations in the United Kingdom exhibited correlated dynamics at scales of 350-400km, owing to the broad scales at which the NAO influenced their dynamics (Saldana et al 2007). Saether et al (2007) reported that the spatial scale of correlation differed between populations of two common European birds: the great tit, Parus major, and the blue tit, Cyanistes caeruleus, partly due to the scale of the environmental forces acting on each population. Spatial correlations among blue tit populations declined substantially at scales >100km whereas great tit populations showed a high degree of coherence across the entire study range (800km) suggesting a more widespread environmental component influencing fluctuations of great tit populations than for blue tit populations (Figure 1.2).…”