Resource availability and the persistence of seed-eating bird populations in agricultural landscapes : a mechanistic modelling approach

1. Reductions in resource availability, associated with land-use change and agricultural intensification in the UK and Europe, have been linked with the widespread decline of many farmland bird species over recent decades. However, the underlying ecological processes which link resource availability and population trends are poorly understood. 2. We construct a spatial depletion model to investigate the relationship between the population persistence of granivorous birds within the agricultural landscape and the temporal dynamics of stubble field availability, an important source of winter food for many of those species. 3. The model is capable of accurately predicting the distribution of a given number of finches and buntings amongst patches of different stubble types in an agricultural landscape over the course of a winter and assessing the relative value of different landscapes in terms of resource availability. 4. Sensitivity analyses showed that the model is relatively robust to estimates of energetic requirements, search efficiency and handling time but that daily seed survival estimates have a strong influence on model fit. Understanding resource dynamics in agricultural landscapes is highlighted as a key area for further research. 5. There was a positive relationship between the predicted number of bird days supported by a landscape over-winter and the breeding population trend for yellowhammer Emberiza citrinella, a species for which survival has been identified as the primary driver of population dynamics, but not for linnet Carduelis cannabina, a species for which productivity has been identified as the primary driver of population dynamics. 6. Synthesis and applications. We believe this model can be used to guide the effective delivery of over-winter food resources under agri-environment schemes and to assess the impacts on granivorous birds of changing resource availability associated with novel changes in land use. This could be very important in the future as farming adapts to an increasingly dynamic trading environment, in which demands for increased agricultural production must be reconciled with objectives for environmental protection, including biodiversity conservation.

[1]  W. Sutherland,et al.  Depletion models can predict shorebird distribution at different spatial scales , 2001, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[2]  R. Freckleton,et al.  Predicting the determinants of weed abundance: a model for the population dynamics of Chenopodium album in sugar beet , 2008 .

[3]  Paul M. Dolman,et al.  The intensity of interference varies with resource density: evidence from a field study with snow buntings, Plectrophenax nivalis , 1995, Oecologia.

[4]  Beatriz Arroyo,et al.  A review of the abundance and diversity of invertebrate and plant foods of granivorous birds in northern europe in relation to agricultural change , 1999 .

[5]  William J. Sutherland,et al.  A spatial depletion model of the interaction between bean geese and wigeon with the consequences for habitat management , 1994 .

[6]  E. Charnov.  Optimal Foraging: Attack Strategy of a Mantid , 1976, The American Naturalist.

[7]  Michael J. Crawley,et al.  The R book , 2022 .

[8]  C. S. Holling.  Some Characteristics of Simple Types of Predation and Parasitism , 1959, The Canadian Entomologist.

[9]  J E Annetts,et al.  Multiple objective linear programming for environmental farm planning , 2002, J. Oper. Res. Soc..

[10]  Jeremy D. Wilson,et al.  Winter habitat associations of seed-eating passerines on Scottish farmland , 2003 .

[11]  Theunis Piersma,et al.  Digestive bottleneck affects foraging decisions in red knots Calidris canutus. I. Prey choice , 2005 .

[12]  Clive W. Anderson,et al.  Predicting the Distribution of Individuals and the Consequences of Habitat Loss: The Role of Prey Depletion , 1993 .

[13]  M. Whittingham,et al.  The selection of stubble fields by wintering granivorous birds reflects vegetation cover and food abundance , 2002 .

[14]  Andrew M. Wilson,et al.  Distribution and abundance of birds and their habitats within the lowland farmland of Britain in winter , 2008 .

[15]  J. Krebs,et al.  Agriculture: Widespread local house-sparrow extinctions , 2002, Nature.

[16]  M. Díaz.  Interspecific patterns of seed selection among granivorous passerines: effects of seed size, seed nutritive value and bird morphology , 2008 .

[17]  G. Siriwardena,et al.  The effect of supplementary winter seed food on breeding populations of farmland birds: evidence from two large‐scale experiments , 2007 .

[18]  G. Walsberg.  Chapter 3 – AVIAN ECOLOGICAL ENERGETICS , 1983 .

[19]  Richard A. Stillman,et al.  Carrying capacity in overwintering migratory birds , 2002 .

[20]  M. Díaz.  Food choice by seed-eating birds in relation to seed chemistry☆ , 1996 .

[21]  William J. Sutherland,et al.  Predicting the response of farmland bird populations to changing food supplies , 2003 .

[22]  D. Noble,et al.  Winter availability of cereal stubbles attracts declining farmland birds and positively influences breeding population trends , 2005, Proceedings of the Royal Society B: Biological Sciences.

[23]  S. Wotton,et al.  Countryside stewardship delivers cirl buntings (Emberiza cirlus) in Devon, UK , 2001 .

[24]  John R. Krebs,et al.  Predicting population responses to resource management , 2001 .

[25]  I. T. Veen.  Daily routines and predator encounters in Yellowhammers Emberiza citrinella in the field during winter , 2008 .

[26]  G. Siriwardena,et al.  Farmland birds and late winter food: does seed supply fail to meet demand? , 2008 .

[27]  William J. Sutherland,et al.  A Spatial Depletion Model of the Responses of Grazing Wildfowl to the Availability of Intertidal Vegetation , 1996 .

[28]  Jeremy D. Wilson,et al.  Seed food preferences of granivorous farmland passerines , 2007 .

[29]  Richard A. Stillman,et al.  Density‐dependent starvation in a vertebrate without significant depletion , 2001 .

[30]  M. Whittingham,et al.  Stubble height affects the use of stubble fields by farmland birds , 2005 .

[31]  Elizabeth H A Mattison,et al.  Bridging the gaps between agricultural policy, land-use and biodiversity. , 2005, Trends in ecology & evolution.

[32]  Alastair H. Fitter,et al.  The ecological flora database. , 1994 .