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Arthropods in diet of Little Bustards Tetrax tetrax
during the breeding season in western France:
Seasonal, age- and sex-related variations in the diet
were studied during March to October.
F. Jiguet
Published online: 29 Mar 2010.
To cite this article: F. Jiguet (2002) Arthropods in diet of Little Bustards Tetrax tetrax during the breeding season in
western France: Seasonal, age- and sex-related variations in the diet were studied during March to October., Bird Study,
49:2, 105-109, DOI: 10.1080/00063650209461253
To link to this article: http://dx.doi.org/10.1080/00063650209461253
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The Little Bustard Tetrax tetrax, a medium-size steppe-
dweller, has suffered a severe decline during this
century in most parts of its range (Goriup 1994),
especially in France (Jolivet 1996, 1997). The main
reasons for this decline are the fragmentation of its
breeding habitat, and the habitat loss or degradation
through agricultural intensification (Goriup 1994),
including increased application of agro-chemicals
(Goriup & Batten 1990, Hellmich 1992). Dramatic
losses in the face of habitat alterations strongly suggest
that active habitat management is required in western
France to maintain the species although comparatively
little is known about their biology.
Adult Little Bustards are apparently omnivorous,
their diet consisting of plant leaves and arthropods
(Cramp & Simmons 1980). Juveniles, in contrast, feed
exclusively on arthropods, at least until three weeks
old, before switching progressively to a vegetarian
diet (Cramp & Simmons 1980). Thus arthropods prob-
ably play a key role in the breeding success of the
species. The main laying period is from May to June for
southern populations (Cramp & Simmons 1980), but
June to July for populations inhabiting western France,
so that rearing takes place mainly in July–August.
Populations inhabiting western France are migratory
(Cramp & Simmons 1980). They are present on their
breeding grounds from March onwards, and leave for
their wintering grounds in October–November (Jiguet
2001).
I report the relative importance and seasonal changes
of arthropods in the diet of Little Bustard populations
inhabiting western France. I also describe seasonal and
sex- or age-related variations in diet. A main aim was
to determine which arthropod orders contributed most
during the laying–rearing period, and thus were poten-
tially involved in determining breeding success of the
species in an intensive agricultural habitat.
METHODS
The study sites where faeces were collected are all
located in western France, in Département des Deux
Sèvres (46°15′N, 0°30′W and 46°55′N, 0°10′W),
Vienne (46°50′N, 0°20′E), Maine-et-Loire (47°07′N,
0°11′W) and Indre (47°15′N, 1°50′E). These sites
cover a total of c. 420 km2of intensive agricultural
habitat and hold low densities of c. 70 displaying males
(Jiguet 2001). Land use in the study sites is a mixture of
winter cereal crops, other winter crops such as oil-seed
rape and peas, spring-sown crops (sunflower and
maize), set-aside and pasture lands and other perma-
Bird Study (2002) 49, 105–109
©2002 British Trust for Ornithology
Arthropods in diet of Little Bustards Tetrax tetrax
during the breeding season in western France
FRÉDÉRIC JIGUET
CEBC-CNRS, F-79360, Villiers en Bois, France
Capsule Seasonal, age- and sex-related variations in the diet were studied during March to October.
Aims To determine which arthropod orders contributed most during the laying–rearing period and those
important in determining breeding success of the species in an intensive agricultural habitat.
Methods Faeces (n= 388, 345 g) and three gut samples were dissected to determine which arthropod
orders contributed most to the diet, especially during the laying–rearing period.
Results Coleoptera were the most numerous prey followed by Orthoptera, Dermaptera and
Hymenoptera. No difference was observed in the diet of adult males and females. Although adults ate
arthropods throughout the breeding season, plant material contributed 97–99% of faecal contents by
weight in each month. Chicks, however, only ate arthropods, notably Coleoptera and Orthoptera, at least
until 2–3 weeks old.
Conclusion Increasing arthropod availability would be a useful management tool for maintaining
endangered Little Bustard populations by potentially increasing chick survival.
*Correspondence author. Present address: CRBPO, 55 rue Buffon,
75005 Paris, France.
Email: fjiguet@mnhn.fr
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106 F. Jiguet
©2002 British Trust for Ornithology, Bird Study, 49, 105–109
nent or semi-permanent crops directed to livestock
rearing.
The stomach and gut of two adult males and one 5-
week-old juvenile that died naturally and accidentally
(not from disease) in the field during the breeding
season in Département des Deux Sèvres were exam-
ined. This gave gave a first indication of which
arthropod orders are eaten by Little Bustard. Faeces
were collected in 1998 and 1999 on display sites and
around nests, from March to October and especially
during the main laying period (June–July).
Faeces were oven-dried at 60°C for three days,
weighed and dissected in order to collect remains of
arthropods that had been ingested. Arthropod remains
were weighed and identified to the taxonomic order
(see Moreby 1988). In each sample, I recorded the
minimum number of ingested individuals for each
arthropod order, using key body parts (Moreby 1988).
A total of 345 g of faeces (representing a total of 388
different faeces from at least 80 different birds) were
collected during the period March–October. Some
analyses used the number of arthropod individuals per
g of faeces (as a mean for a collected sample of one or a
few faeces). Over the period from April to July, I
collected faeces of males (n= 47 faeces; 79 g), females
(n= 80 faeces; 105 g), chicks (n= 9 faeces; 4 g) and
mixed flocks (n= 252 faeces; 157 g). Faeces were
attributed to males when found on display sites not
visited by females. In the same way, faeces were attrib-
uted to females when found in fields visited only by
females, and to mixed flocks when it was not possible
to assign them to a particular individual (post-
breeding gathering, display site visited by females, male
frequenting a nesting field). Juvenile’s faeces were
collected in fields frequented by family parties, and were
easy to recognise because of their small size and appear-
ance. A total of 112 faeces were collected in June–July,
representing 250 g of faeces. Outside these periods,
birds gather in pre- or post-breeding flocks, so the faeces
could not be assigned to any particular individuals.
For the purpose of analyses, numbers of arthropods in
faeces were transformed as log (1 + y) and weight
proportions as arcsine√(y) before conducting the tests.
Statistical analyses were conducted using SYSTAT 9.0
(Wilkinson 1990), and considered different at P< 0.05.
RESULTS
Arthropods in stomach and gut contents
Three stomach/gut contents of three birds were exam-
ined. I identified a total of 114 arthropods in these con-
tents, with five different orders encountered (Table 1).
Arthropods in faeces
The faeces contained at least 719 arthropods (465 for
June–July). Numbers and proportions of the different
arthropod orders are given in Table 1. A few arthropod
remains were identified to species. These were two
orthopterans (Gryllotalpa gryllotalpa,Gryllus campestris),
five beetles (Feronia madida, Feronia cuprea,Amara
cursitans,Dermestes maculatus) and a bug (Corizus
hyoscyami). The four insect orders contributing more
than 5% of records were Coleoptera, Orthoptera,
Dermaptera and Hymenoptera. I retained these four
orders for further investigation on seasonal, sex or age-
related variations in the numbers of arthropods in faeces.
Table 1. Numbers and proportions of arthropod orders identified in stomach and gut contents, and in faeces of Little Bustard Tetrax tetrax.
Proportions in bold are those over 5%. 1, Adult male, died 9 Jun 1999; 2, adult male, died 20 Aug 1998; 3, juvenile, died 17 Aug 1999.
Stomach and gut contents Faeces March–October Faeces June–July
Arthropod order 1 2 3 % n%n%
Insects
Coleoptera 25 8 51 73.6 402 55.9 265 57.1
Dermaptera 3 – 2 4.4 148 20.6 102 21.9
Orthoptera – 17 2 16.7 79 11.0 59 12.7
Hymenoptera – – – – 58 8.1 18 3.9
Lepidoptera – 1 – 0.9 22 3.1 14 3.0
Heteroptera 3 2 – 4.4 3 0.4 3 0.6
Diptera – – – – 3 0.4 – –
Arachnids
Opilionae – – – – 3 0.6 3 0.6
Araneidae – – – – 1 0.2 1 0.2
Total 31 28 55 100 719 100 465 100
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Variations in relation to season, age and sex
The relative proportions by dry weight of green plant
material and arthropods in faeces varied significantly
over the breeding season (Fig. 1, adults only). A signif-
icant seasonal variation was found in the proportion by
dry weight of arthropods in faeces (F7,79 = 3.78, P=
0.001). Considering only the laying period (i.e.
June–July), I found no difference in the proportion by
dry weight of arthropods in faeces between males and
females (F1,24 = 0.51, P= 0.482) but the number of
identifiable arthropods was greater in chicks’ faeces
than in those of adults (F1,30 = 12.81, P= 0.001).
Numbers of Coleoptera and Orthoptera per g of fae-
ces varied significantly with the season, but not
numbers of Dermaptera and Hymenoptera (Fig. 2;
ANOVA; F7,79 = 2.27, P= 0.04, F7,79 = 2.86, P= 0.01, F7,79
= 2.06, P= 0.06 and F7,79 = 0.62, P= 0.74, respectively).
Chi-squared tests revealed a lower proportion of
Hymenoptera in faeces during June–July than during
the rest of the year (χ21= 26.67, P= 0.000). No differ-
ence was found for other orders (Coleoptera,
Dermaptera and Lepidoptera), while Orthoptera were
slightly more numerous in summer, though the differ-
ence was not significant (χ21= 3.42, P= 0.06).
For the period April–July, there were 55 faecal sam-
ples that could be attributed to particular individuals of
known sex and age (juvenile vs.adult). I performed an
analysis of covariance to test whether the number of
Coleoptera, Orthoptera, Dermaptera and Hymen-
optera varied according to the status of the bird (factor)
and the season (covariate). I found more Coleoptera
and Orthoptera in chick’s faeces compared with that of
adult males and females, and a seasonal effect for
Orthoptera (Table 2, Fig. 3). While comparing the same
age/sex groups, there was no difference for Dermaptera
and Hymenoptera orders, but Dermaptera were more
numerous in summer (Table 2, Fig. 3). Moreover, there
was no variation according to the sex of adult birds in
the number of individual arthropods per g of faeces for
the four insect orders, when considering the whole
breeding season or even only the laying period.
DISCUSSION
Methodological considerations
The method used to compare the proportions by dry
weight of arthropod and green plant remains in faeces
©2002 British Trust for Ornithology, Bird Study, 49, 105–109
Little Bustard diet in France 107
Proportion in diet
0.90
0.92
0.94
0.96
0.98
1.00 Arthropods Green plants
Mar
(26) Apr
(23) May
(58) Jun
(21) Jul
(59) Aug
(87) Sep
(44) Oct
(70)
Figure 1. Seasonal changes in the proportion by dry weight of
arthropods and green plant material in adult Little Bustard Tetrax
tetrax faeces, during the whole period of presence of the species on
its breeding grounds. Numbers of faeces per month are given in
brackets.
Number of individuals per g of faeces
0
1
2
3
4
5
6Orthoptera Coleoptera
Hymenoptera Dermaptera
Mar Month
Apr May Jun Jul Aug Sep Oct
Figure 2. Seasonal changes in numbers of insect individuals
encountered per gram of adult Little Bustard Tetrax tetrax faeces,
during the whole period of presence of the species on its breeding
grounds. Only the four dominant insect orders are considered here.
Table 2. Results of analyses of covariance investigating the
number of individuals per gram of faeces for four insect orders
according to the status of the bird (age/sex as factor) and the month
of faeces collection (April–July, as covariate). Pvalues in bold are
those under 0.05.
Insect order Source df FP
Coleoptera Status 2 3.49 0.038
Month 1 0.80 0.376
Orthoptera Status 2 16.33 < 0.001
Month 1 5.10 0.028
Dermaptera Status 2 1.67 0.198
Month 1 4.86 0.032
Hymenoptera Status 2 0.21 0.810
Month 1 0.03 0.868
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is subject to a number of biases. Notably there was no
correction for differential digestibility between plant or
animal species. The proportion of arthropods in the
diet appeared low, but vegetation may be harder to
digest and provide less energy or protein. Indeed, this
might be true on nutritional grounds, as has been
shown for other steppe-dwelling birds and grouse
(Lagopus and Tetrao) species (Ponce 1991). Arthropods
remain a critical resource for breeding in the Little
Bustard, especially for rearing the chicks.
Arthropods in the diet of Little Bustards
The animal prey of Little Bustard consisted of seven
orders of insects and two of arachnids. Faecal analyses
highlighted the importance of Coleoptera, while
Dermaptera and Orthoptera were also commonly
present. Stomach and gut contents did not suggest that
any other animal groups were important in the
breeding diet (although the sample size was low).
Hymenoptera were not commonly found in faeces and
were always almost intact when found, indicating their
low digestibility.
Previous studies on Little Bustard diet highlighted
the predominance of beetles, grasshoppers and earwigs
(Cramp & Simmons 1980). Although snails, earth-
worms, frogs and voles have also been recorded, this
study suggests that these are rare prey. The only non-
arthropod animal we saw eaten by a Little Bustard was
a slug. The diet of the Great Bustard Otis tarda has been
108 F. Jiguet
©2002 British Trust for Ornithology, Bird Study, 49, 105–109
well studied (Lane et al. 1999, Lucio 1985, Palacios
et al. 1975). This larger species preys mainly on
Coleoptera and Orthoptera , but occasionally eats
small rodents (Lane et al. 1999).
Seasonal and age-related variations
Most of the adult diet consisted of green plant materi-
al, even in summer when arthropods reached their
highest abundance. However arthropods were present
in the diet throughout the breeding season, although
they were mostly taken during the summer, i.e. from
June to August. The number of arthropod individuals
per g of faeces peaked in July, while arthropod biomass
in faeces peaked in August, suggesting that arthropods
of larger size were consumed in the latter month. In the
Great Bustard, arthropods were common in faeces from
August to October, during the high abundance of
Acrididae, while they were almost absent from the diet
in July despite the high availability of insects at this
time of year (Lane et al. 1999).
Regardless of age and sex, the most common arthro-
pod prey of Little Bustards were beetles, representing
at least 56% of the animal diet by number. This is
similar to their contribution to the animal diet of
Great Bustard (Lane et al. 1999). Orthoptera largely
contributed to the diet during the summer, i.e.
June–August. Orthoptera numbers peak in July–August
in southwestern Europe, with the dispersion of imma-
ture and adult Acrididae (Louveaux 1991, Louveaux
et al. 1988). This may explain why Little Bustards rarely
eat them outside that period, as suggested for Great
Bustards (Lane et al. 1999).
The highest number and relative biomass of arthro-
pods were found in chicks’ faeces. Furthermore, plant
material was never found in chicks’ faeces, illustrating
their exclusive animal diet, at least until a few
weeks old. Juveniles mainly fed on Coleoptera and
Orthoptera. By the rearing period, Orthoptera are
abundant, large and presumably energetically advanta-
geous to pursue.
Conservation implications
Arthropod numbers are declining in agricultural
habitats (Potts 1997) due to the intensification of
agricultural practices (Aebischer 1990, Burel et al.
1998, Samways & Sergeev 1997). Critically declining
numbers of Grey Partridges Perdix perdix are related to
diminishing permanent cover (Panek 1994, Potts
1986) and to depressed chick survival due to pesticide
Number of individuals per g of faeces
0
1
2
3
4
5
6
Male Female Chick
7
Coleoptera Invertebrate order
Orthoptera Dermaptera Hymenoptera
Figure 3. Numbers of insect individuals per gram of Little Bustard
Tetrax tetrax faeces, for males, females and chicks. Only the four
dominant insect orders are considered here. Significantly higher
numbers of Coleoptera and Orthoptera were recorded in faeces
dropped by chicks. The period considered is April–July, as the birds
gathered in flocks outside these months.
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©2002 British Trust for Ornithology, Bird Study, 49, 105–109
Little Bustard diet in France 109
effects on invertebrate resource (Rands, 1985, 1986,
Panek 1997). In intensive agricultural habitats,
changes in agricultural practices and land cover have
greatly reduced nesting habitat availability for female
Little Bustards (Jiguet et al. 1998, 2000, Salamolard &
Moreau 1999). Nests are located in fields with high
prey biomass (Jiguet 2001). Since young chicks seem to
feed exclusively on arthropods (Cramp & Simmons
1980, this study), the availability of suitable prey may
strongly influence breeding success. Conservation
measures for this endangered species should include
provision of a high abundance of such prey (e.g.
Coleoptera and Orthoptera) in case it influences chick
survival (see Lane et al. 1999, Rands 1985).
ACKNOWLEDGEMENTS
I thank all who collected faeces: Jean-Yves Airault, Alain
Armouet, Vincent Bretagnolle, Marie-Hélène Froger, Sophie
Gateff, Jean-Michel Lett and David Ollivier. Alain Armouet
also provided a dead male. My special thanks go to Beatriz
Arroyo, Vincent Bretagnolle, David Harper and an anony-
mous referee who provided helpful comments on this paper.
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