Agriculture, Ecosystems and Environment 77 2000 219–226
Factors affecting corn bunting Miliaria calandra abundance in a Portuguese agricultural landscape
C. Stoate
a,∗
, R. Borralho
b
, M. Araújo
b,1
a
The Game Conservancy Trust, Fordingbridge, Hampshire SP6 1EF, UK
b
ERENA, Av. Visconde Valmor 11-3
◦
, 1000 Lisbon, Portugal Received 14 December 1998; received in revised form 18 June 1999; accepted 1 July 1999
Abstract
Breeding and wintering abundance of corn buntings in an agricultural landscape of Alentejo southern Portugal was assessed in relation to agricultural intensification and other environmental variables during 1994–1997, using distance sampling and
multivariate regression. Bird abundance was lowest in intensively managed farmland in both seasons, and was related positively to fallow area in winter and to the presence of game management and oats in spring. Fallows and oats were associated
with extensively managed farmland, but the implementation of a managed hunting regime was unrelated to agricultural intensification. The importance of extensive arable systems to corn bunting conservation is discussed. ©2000 Elsevier Science
B.V. All rights reserved.
Keywords: Agricultural intensification; Breeding abundance; Fallow; Montado; Winter abundance; Portugal
1. Introduction
Corn buntings Miliaria calandra are associated, throughout their distribution range, with arable land-
scapes. Their numbers have declined in northern Europe since the 1960s as a result of agricultural in-
tensification Tucker and Heath, 1994. This decline is attributed to increased winter mortality, caused
by reduced abundance of winter food Donald and Evans, 1994, and to poor breeding performance
caused by increased use of agro-chemicals Aebischer and Ward, 1997; Brickle and Harper, in press. In-
∗
Corresponding author. E-mail address: chris.stoateukonline.co.uk C. Stoate.
1
Present address: Biogeography and Conservation Laboratory, The Natural History Museum, Cromwell Road SW7 5BD London,
UK. Tel.: +44-1425-652381; fax: +44-1425-651026.
creased use of herbicides throughout northern Europe has resulted in the loss of many arable weeds, and
hence of phytophagous invertebrates, which provided an essential source of food for many farmland birds,
as Potts 1986 demonstrated convincingly for grey partridge Perdix perdix.
Corn bunting breeding densities are currently highest in Turkey, Spain and Portugal Diaz and
Telleria, 1997, where their numbers appear to be stable. Although cereal production has intensified
in parts of these countries, there still are large ar- eas of extensively managed farmland Bignal and
McCracken, 1996. In Portugal, Alentejo is the main cereal growing region, and extensive systems
are still widely adopted there. Corn bunting has a widespread distribution in this region, and is de-
scribed as abundant Rufino, 1989; Elias et al., 1999.
0167-880900 – see front matter ©2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 9 9 0 0 1 0 1 - 2
220 C. Stoate et al. Agriculture, Ecosystems and Environment 77 2000 219–226
In these extensive arable systems, grazed fallow pro- vides a source of food in the form of seeds in winter
and invertebrates in summer. Cereal crops also sup- port an invertebrate community with relatively large
insects, such as caterpillars Lepidoptera larvae and grasshoppers Orthoptera, taken by corn buntings dur-
ing the breeding season in the north of their range Brickle and Harper, in press. This study assesses the
abundance of corn buntings in December and April in relation to three arable systems and other environ-
mental variables in an agricultural landscape of Baixo Alentejo, southern Portugal, considering, in particu-
lar, various levels of agricultural intensification, and the potential effects of fallow area and private game
interests.
2. Methods
