1. The little bustard Tetrax tetrax is among many birds thought to be decli
ning because of agricultural intensification in western Europe. In contrast
with the situation elsewhere, bustard numbers have greatly increased durin
g the last 50 years in the Crau, southern France, as agriculture has been d
eveloping. We wished to ascertain which features of agricultural developmen
t might have supported this population increase.
2. Using data on habitat-specific densities obtained by surveys of the Crau
in 1998 and 1999, we assessed how breeding male little bustards used habit
ats representing various levels of agricultural intensification. We also do
cumented historical changes in bustard numbers and agricultural trends in t
he Crau, comparing them with present patterns of habitat use, to determine
how changes in farmed landscapes may have driven population trends.
3. Male bustards used natural steppe and extensive agricultural habitats (f
allow, grazed crops., legume crops), whereas more intensive agricultural ha
bitats (hay-meadows, grain crops) were little used. Mean densities on exten
sive agricultural habitats were always high, but densities on steppe varied
with landscape composition: densities were low where steppe was dominant i
n the landscape, but high where steppe and extensive agriculture were mixed
.
4. Available literature showed that little bustards settled in the Crau aro
und 1950, after 40% of the original steppe had been converted into arable l
and. We estimate a current population of 473-539 breeding males. Only 17% o
f the original steppe remains, but extensive agricultural habitats still re
present 30% of arable land.
5. Both historical data and present habitat use suggest that little bustard
population trends in the Crau are driven by the development of extensive a
griculture. Extensive agricultural habitats may provide little bustards wit
h resources unavailable or scarce in natural steppe. Severe declines in lit
tle bustard numbers observed elsewhere could be reversed within a few decad
es by restoring extensive agricultural habitats. The potential impact of cu
rrent European agricultural policies is discussed, with special reference t
o agri-environmental measures and set-aside policy.
6. This work provides an example of an avian species that benefits from cul
tivated landscapes, providing that they are extensive rather than intensive
. We propose a simple conceptual model to illustrate how little bustards, a
nd possibly grassland birds in general, might respond where natural habitat
s are modified along orthogonal axes representing cultivation and agricultu
ral intensification.