Misapplied Ecology: Investigations Of Population Decline In The House Sparrow

Abstract

Editor's commEnt This paper reviews the literature in relation to the accepted decline in the House MISAPPLIED ECOLOGY: INVESTIGATIONS OF POPULATION DECLINE IN THE HOUSE SPARROWEcology aims to explain the distribution and abundance of organisms, and to this end has generated a vast array of theory, empirical data and models. However it has been unable to offer a robust explanation of the rapid decline of a common and conspicuous species, the House Sparrow Passer domesticus, which lives in close proximity to human populations. This is despite intensive analysis of long-term datasets on the species' distribution, abundance and demography, and the implementation of a range of field investigations. Nevertheless, a tacit consensus among researchers has coalesced around the hypothesis that population decline is related to deteriorating food availability, though with different ultimate causes in urban and rural populations. Recently, however, evidence has emerged that the decline of sparrow populations in Britain can be simply explained as a consequence of a build up in the population of its major predator, the Eurasian Sparrowhawk Accipiter nisus.

Changes In Tree Sparrow Passer Montanus Populations From Urban Parks

“…Here it should be made clear that, contrarily to pine martens, the presence in urban green areas of stone martens Martes foina had no impact on breeding Tree Sparrows or other hole nesters (Tomiałojć 1980a, 2011, Klausnitzer 1987 . At least since the 1960 .…”

“…on the outskirts of Warsaw (Pinowski 1968), hardly find a support in Silesian data . For example, the censuses started in Legnica plots three years after the "winter of the century" 1962/63 have revealed fairly good Tree Sparrow numbers, similarly as in parks of Wrocław there were no persistent "downs" after harsh or long winters 1978/79, 1986/87 or 2009/10 (Tomiałojć 2007, 2011 Fig . 1) .…”

“…Therefore I share a view of C .P . Bell (2011), on an urgent need of detailed case studies of the predator-prey relationship (c .f . Tomiałojć 1980a) as one of possible ways to find reasons of the recent songbird decline, perhaps additional to food or nest-site shortage, pathogens, or chemical contamination .…”

Investigating temporal and spatial correlates of the sharp decline of an urban exploiter bird in a large European city

“…Actually, several recent studies have emphasized the likely role of decaying food quality and/or quantity in the decline of urban House Sparrows (Liker et al 2008;Meillère et al 2017;Moudrá et al 2018). Because invertebrate preys are crucial for the growth and the development of nestlings (Bolger 2001;Vincent 2006;Seress et al 2012;Meillère et al 2015a), and probably for survival over their first year of life (Bell 2011), a lack of invertebrate preys during the reproductive period has also been suggested as a proximate cause of the decline of urban House Sparrows (Vincent 2006;Bell 2011). Yet, despite our fine-scale study of census site characteristics, we were not able to explain the trend over time of House Sparrows using habitat characteristics.…”

“…In addition, the decline of House Sparrows could also be the result of habitat modification, and more specifically of the disappearance of feeding, sheltering, or nesting sites (Shaw et al 2008;Angelier and Brischoux 2019). This decline could also result from a change in food supply (Liker et al 2008;Bell 2011), notably because of a lack of invertebrate preys, which are crucial for the survival and development of the chicks (Anderson 2006;Vincent 2006;Auman et al 2008;Peach et al 2014;Meillère et al 2017). Such preys are likely to be found in higher densities near green space areas (Jones and Leather 2012) and House Sparrow decline would therefore be expected to vary according to vegetation accessibility.…”