Colonial, more widely distributed and less abundant bird species undergo wider population fluctuations independent of their population trend

Abstract

Understanding temporal variability in population size is important for conservation biology because wide population fluctuations increase the risk of extinction. Previous studies suggested that certain ecological, demographic, life-history and genetic characteristics of species might be related to the degree of their population fluctuations. We checked whether that was the case in a large sample of 231 European breeding bird species while taking a number of potentially confounding factors such as population trends or similarities among species due to common descent into account. When species-specific characteristics were analysed one by one, the magnitude of population fluctuations was positively related to coloniality, habitat, total breeding range, heterogeneity of breeding distribution and natal dispersal, and negatively related to urbanisation, abundance, relative number of subspecies, parasitism and proportion of polymorphic loci. However, when abundance (population size) was included in the analyses of the other parameters, only coloniality, habitat, total breeding range and abundance remained significantly related to population fluctuations. The analysis including all these predictors simultaneously showed that population size fluctuated more in colonial, less abundant species with larger breeding ranges. Other parameters seemed to be related to population fluctuations only because of their association with abundance or coloniality. The unexpected positive relationship between population fluctuations and total breeding range did not seem to be mediated by abundance. The link between population fluctuations and coloniality suggests a previously unrecognized cost of coloniality. The negative relationship between population size and population fluctuations might be explained by at least three types of non-mutually exclusive stochastic processes: demographic, environmental and genetic stochasticity. Measurement error in population indices, which was unknown, may have contributed to the negative relationship between population size and fluctuations, but apparently only to a minor extent. The association between population size and fluctuations suggests that populations might be stabilized by increasing population size.

A status of guinea fowl (Numida meleagris) and pheasant (Phasianus colchicus) population transferred from wildlife to the breeding assessed based on the histone H1.c’ polymorphic variation

“…1 Although the guinea fowl and pheasant are the least concern species constituting the extremely large populations, 2 their local level can change due to the various reasons, alike demographic casualty and geographical distribution as well as reproductive rate and the susceptibility for environmental changes. 3 An equally important factor affecting population is a genetic diversity that represents the genetic difference within population or between the populations. Genetic diversity conditioned by allelic diversity and heterozygosity is desirable for maintenance of the proper population status, 4 providing its potential for long-term adaptation and fitness.…”

Last Glacial Maximum led to community-wide population expansion in a montane songbird radiation in highland Papua New Guinea

“…Further, we estimated demographic parameters for the best model and generated 500 datasets based on the posterior distribution to estimate the bias and precision in parameter estimation. We assumed a generation time of 1 year for all three species, which is a widespread estimate for the generation time of such small-sized passerines [ 63 ].…”

Variability, skipped breeding and heavy‐tailed dynamics in an Antarctic seabird

“…Large temporal variation in animal species hinders the ease with which time series for abundance can be used to accurately assess and predict population trends through time (Bjørnstad & Grenfell, 2001; Buschke et al, 2021; Sæther et al, 2004). While large population fluctuations are seen across the animal kingdom (Gravel et al, 2011), time series of abundance are particularly variable for colonially breeding birds (Anderson et al, 2017; Cuervo & Møller, 2017). Here, we study population abundance time series of the Adélie penguin Pygoscelis adeliae , a well‐studied colonially breeding Antarctic seabird.…”

“…Heavy‐tailed dynamics in animal populations and the associated extreme events (Anderson et al, 2017) have significant consequences for population viability (Cuervo & Møller, 2017; Fey et al, 2015). Because of their disproportional effect on the systems in which they occur, these ‘black‐swan’ events are an important consideration in predicting the persistence and viability of animal populations (Boyce, 1992; Mangel & Tier, 1994).…”