Agri-environment effects on birds in Wales: Tir Gofal benefited woodland and hedgerow species

Author(s): Dadam, D. & Siriwardena, G.M.

Published: July 2019

Journal: Agriculture, Ecosystems & Environment Volume: 284

Digital Identifier No. (DOI): 10.1016/j.agee.2019.106587

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Abstract

Agri-environment schemes (AESs) have shown mixed success across Europe in terms of meeting environmental targets. Tir Gofal, the first widespread AES in Wales, ran from 1999 to 2013. Here we test the effects of its options on bird population growth rates, using the annual BTO/JNCC/RSPB Breeding Bird Survey (BBS). Using over 400 1-km BBS squares, we applied a log-linear analytical approach that models the average change in expected abundance of individual species between consecutive years, testing the effects of spatio-temporal covariates (here, local quantities of Tir Gofal management and appropriate controls). Management options within the scheme were grouped according to their intended mode of impact on birds and commonalities in the habitat changes that they describe. Overall, 28/97 tests conducted produced positive results, and only four negative ones, a pattern that was also found among priority species alone (14 and two of 58 tests, respectively), involving eight of 17 priority species in Wales. Out of the ten groups of options considered, those concerning woodland, scrub and hedgerows were the most successful, each showing a predominance of positive effects across the bird species tested. Arable and grassland open-field options produced some positive effects, but failed to deliver detectable benefits for priority species, with wet grassland and waders being a particular gap. The non-significant effects found may reflect low analytical power, confounded option and landscape variation or failures of those options to address the key factors limiting species’ populations. Overall, however, this study provides good evidence that Tir Gofal had positive effects on many target bird populations in Wales, showing that the scheme contributed positively to key conservation policy targets, even if significant effects were not detectable on all such species.

Abstract

Agri-environment schemes (AESs) have shown mixed success across Europe in terms of meeting environmental targets. Tir Gofal, the first widespread AES in Wales, ran from 1999 to 2013. Here we test the effects of its options on bird population growth rates, using the annual BTO/JNCC/RSPB Breeding Bird Survey (BBS). Using over 400 1-km BBS squares, we applied a log-linear analytical approach that models the average change in expected abundance of individual species between consecutive years, testing the effects of spatio-temporal covariates (here, local quantities of Tir Gofal management and appropriate controls). Management options within the scheme were grouped according to their intended mode of impact on birds and commonalities in the habitat changes that they describe. Overall, 28/97 tests conducted produced positive results, and only four negative ones, a pattern that was also found among priority species alone (14 and two of 58 tests, respectively), involving eight of 17 priority species in Wales. Out of the ten groups of options considered, those concerning woodland, scrub and hedgerows were the most successful, each showing a predominance of positive effects across the bird species tested. Arable and grassland open-field options produced some positive effects, but failed to deliver detectable benefits for priority species, with wet grassland and waders being a particular gap. The non-significant effects found may reflect low analytical power, confounded option and landscape variation or failures of those options to address the key factors limiting species’ populations. Overall, however, this study provides good evidence that Tir Gofal had positive effects on many target bird populations in Wales, showing that the scheme contributed positively to key conservation policy targets, even if significant effects were not detectable on all such species.
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