Abundance of the wood mouse Apodemus sylvaticus and the Algerian mouse Mus spretus (Rodentia, Muridae) in different habitats of Northern Algeria

Mammalian Biology

Mamm. biol. 67 (2002) 34±41 ã Urban & Fischer Verlag http://www.urbanfischer.de/journals/mammbiol

Zeitschrift fuÈr SaÈugetierkunde

Original investigation

Abundance of the wood mouse Apodemus sylvaticus and the Algerian mouse Mus spretus (Rodentia, Muridae) in different habitats of Northern Algeria By K. KHIDAS, NORA KHAMMES, SAMIA KHELLOUFI, S. LEK, and S. AULAGNIER DeÂpartement de Biologie, Universite M. Mammeri, Algeria, Centre d'Etude des SysteÁmes Aquatiques Continentaux, Universite P. Sabatier, France and Institut de Recherche sur les Grands MammifeÁres, I.N.R.A., France Receipt of Ms. 02. 11. 1998 Acceptance of Ms. 01. 06. 2001

Abstract The relationship between the abundance of two rodents, the wood mouse Apodemus sylvaticus and the Algerian mouse Mus spretus, and habitat characteristics were studied in Great Kabylia (Northern Algeria) at the end of the breeding season, when mice densities were at their highest level. Eleven habitat characteristics were recorded to describe 18 sampling sites. A linear multiple regression analysis revealed that the abundance of wood mice associated with rocks and stone blocks, and with low woody vegetation. Algerian mice were associated with a low cover of high woody vegetation, and with bare ground. Other habitat characteristics, such as modification of land by human activities, were also important and affected the abundance of these two species. These patterns are discussed in relation to the feeding habits and the anti-predatory behaviour of the species. The interspecific relationships of the two species are hypothesised. Key words: Apodemus sylvaticus, Mus spretus, abundance modelling, habitat selection, North Africa

Introduction The wood mouse Apodemus sylvaticus and the Algerian or short-tailed mouse Mus spretus live in the western part of the Palaearctic region (Corbet 1978). While the former is ubiquitous (Canova and Fasola 1991; Corbet and Southern 1977), the latter requires Mediterranean conditions (Moreno and Barbosa 1992; Orsini et al. 1982). Despite a large body of research on the wood mouse in Europe, the relationship between habitat characteristics and the abundance of this species remains controversial (AlcaÂntara and TellerõÂa 1991; Canova et al. 1994; Churchfield et al. 1997; Fa et al. 1616-5047/02/67/01-034 $ 15.00/0.

1992; Fitzgibbon 1997; Fons et al. 1988; Garcia et al. 1998; Gurnell 1985; Montgomery and Dowie 1993; Montgomery et al. 1991; Moreno and Barbosa 1992). On the other hand, little is known about the Algerian mouse in any part of its range. Moreover, studies on these species are very scarce in Northern Africa, the southernmost part of their range, where little is known about their ecology. Khidas (1993) previously surveyed the major distributional patterns of the two species in Great Kabylia. As a further investigation, the aim of the present study was to identify the main habi-

Abundance of Apodemus sylvaticus and Mus spretus in different habitats tat features that control their abundance during the breeding season in this region.

Material and methods Study area The study was conducted in Great Kabylia, Northern Algeria (36°22' to 36°55' N, 3°35' to 5°05' E). The altitude ranged from 10 to 1 500 metres in the study area. At lower altitudes (£ 200 m above sea level), the daily range of temperature in August, the warmest month of summer in Great Kabylia, was 19.1±35.5 °C, and in January, the coldest month of winter, 5.4±16.5 °C, depending on the localities. At higher altitudes (³ 1 400 m a. s. l.), the daily range of temperature in August was 19.6±25.7 °C, and in January 1.7± 5.1 °C. The wet season occurred in the region from September±October to May±June; the dry season lasted 3 to 4 months depending on the altitude and the years. The annual rainfall varied between 600 and 1 300 mm per year, with an average of 1 000 mm per year for the whole area (Office National de la MeÂteÂorologie, Algiers; data covering at least 20 years for this region). According to vegetation features, six main habitat types where identified: (1) cultivated fields (market gardening, wheat), interspersed with rows and small-sized plots of woody vegetation; (2) early successional zones with some shrubs dominated by Cistus monspeliensis, and sparse trees such as Olea europaea and Pinus halepensis; (3) scrubland of Pistacia lentiscus and Arenaria maritima; (4) dense maquis dominated by C. monspeliensis, Phyllirea latifolia, and Calycotome spinosa, with few trees (Quercus suber); (5) plantations of O. europaea, Eucalyptus spp, and P. halepensis, with more or less dense shrub cover dominated by C. spinosa, Crataegus oxyacantha, Rhamnus alaturnus, Lonicera implexa, P. lentiscus, Pistacia latifolia, depending on the substratum; (6) oldgrowth evergreen forests of Quercus rotundifolia, Cedrus atlantica, Quercus canariensis, Q. suber, with sparse to dense undergrowth.

Sampling Rodent populations were sampled at 18 sites representative of the six main habitat types. Each sampling site was characterised by 11 environmental variables listed in table 1. These variables except the altitude, were evaluated by visual estimation in a 2-ha surface area where mice were trapped.

35

Rodents were trapped according to the standardised line transect method (Spitz et al. 1974). One or two 150 m-long trap-lines were set at a time, depending on the characteristics of the sampling site. Each trap-line was made up of 51 snaptraps with an inter-trap spacing of 3 m. Traps were baited with dates and dried figs, and set during two consecutive days. They were checked twice a day, in the early morning and before sunset. In order to standardise our trapping, we conducted sampling at the end of the breeding season, during the time when mice densities were at their highest level, i. e. late February to early May in lower altitudes (< 800 m a. s. l.), and late March to early June in higher altitudes (> 1 400 m a. s. l.) (see AntuÂnez et al. 1990; Fons and Saint-Girons 1993; Hamdine and Poitevin 1994; Harich and Benazzou 1990; Kowalski 1985; Saint-Girons and Thouy 1978; Vargas et al. 1991). From 1987 to 1994, 29 trapping sessions were carried out, which represented 16 236 m of trap-lines operated during 5 412 trap-nights.

Data analysis The number of individuals caught per 100 trapnights expressed the relative abundance of the two mice species. Habitat characteristics were scored as follows: three degrees for major biotic zones according to total vegetational biomass; eight degrees for vegetation type according to complexity; five degrees for vegetation, rocks, and for bare ground according to classes for percentage cover on ground; four degrees for heterogeneity according to the number of patches of woody vegetation over the trap-line; and four degrees for human perturbations according to the intensity of the activities. Linear multiple regression models were computed to explain the relationship between the abundance of each species and the habitat characteristics. The analysis involved two procedures: first, the relative abundance of one species was regressed to all of the variables simultaneously, considering only one variable or a subset of variables at one time (forward selection; here referred to as ªstepwise offº), until obtaining the most significant model (Sokal and Rohlf 1995); and secondly, we performed a stepwise procedure in which variables were removed when an alternative variable explained a higher proportion of the total variation (referred to as ªstepwise onº). We specified 0.05 for the p-to-enter value and 0.10 for the p-to-remove value in the stepwise procedure (see Sokal and Rohlf 1995). Analysis of variance (ANOVA) was conducted to test the significance of the re-

36

K. KHIDAS et al.

Table 1. Variables used to characterise the wood mouse and Algerian mouse habitats in Great Kabylia, Northern Algeria. Variables

Descriptions

1. Zone

Qualitative variable for the major biotic zones found in the region, including cultivated plains and valleys, olive groves area, and forested area

2. Veg-type

Qualitative variable for vegetation type including in increasing order of complexity, cultivated fields, meadows with dense grass cover, meadows with sparse shrubs, maquis and scrublands, dense maquis with sparse trees, tree plantations, old-growth forests, and complex mosaics of vegetation

3. Hwv

Percentage cover on ground of high woody vegetation (trees and tall shrubs) with a height generally topping 4±5 m, according to five classes of values: < 10%, 10±25%, 25±50%, 50± 75%, and > 75%

4. Lwv

Same as (3) for low woody vegetation generally less than 2 m high (shrubs and undergrowth)

5. Wv

Same as (3) for gross woody vegetation (Hwv + Lwv)

6. Hb

Same as (3) for herbaceous vegetation

7. RB

Same as (3) for rocks and stone blocks

8. BGr

Percentage of bare ground according to classes of values same as (3)

9. Htg

Heterogeneity evaluated according to the number of woody vegetation patches over the trap-line: 1±2 units, 3 units, 4 units, and ³ 5 units

10. HumP

Qualitative variable for human perturbations evaluated according to the intensity of the activities (mainly the development of agriculture): nil or feeble, low, medium, and high; see LONG (1974)

11. Alt

Altitude

gression. A first set of analyses was carried out with the relative abundance of wood mice considered as the dependant variable, and the relative abundance of Algerian mice as well as the habitat characteristics as the independent variables. A second set of analyses was performed reversing the two mice species. The SystatÒ statistical package was used for computations.

p = 0.009). As a first result, the abundance of wood mice was correlated with the cover of rocks (r = 0.776; p < 0.001); the abundance of Algerian mice was positively correlated with bare ground (r = 0.524; p = 0.026), and negatively correlated with the cover of high woody vegetation (r = ±0.557; p = 0.016).

Results

Relations between habitat characteristics and the abundance of wood mice

A Pearson (pairwise) correlation matrix for all the variables enabled the removal of major biotic zones, vegetation type, gross woody vegetation, and altitude, which were largely redundant; so only seven habitat characteristics were retained for the analyses. There was still a negative relationship between human perturbations and the cover of high woody vegetation (r = ±0.542, p = 0.02) and of low woody vegetation (r = ±0.681, p = 0.002); herbaceous cover was negatively correlated with the cover of high woody vegetation (r = ±0.595,

The regression parameters (stepwise off and stepwise on) are summarised in table 2 where the independent variables are given in decreasing order of importance. A high proportion of almost 76% (R2 = 0.757) of the variation in the abundance of wood mice was significantly explained (p = 0.001) by the cover of rocks and of low woody vegetation, human perturbations, and by the relative abundance of Algerian mice. The residuals in this regression model were low (min = ±3.199; max = 3.625; mean = 0; SD =

Abundance of Apodemus sylvaticus and Mus spretus in different habitats

37

Table 2. Estimation of the abundance of wood mice by two linear-multiple regression analyses, stepwise off and stepwise on. (Ms: relative abundance of Algerian mice; see legend in table 1) Variable

Coefficient

Std error

Std coef

Tolerance

t

P (2 tail)

Stepwise Off Constant RB Lwv HumP Ms

±5.952 2.275 1.567 0.599 0.578

2.585 0.412 0.620 0.409 0.404

0.000 0.795 0.473 0.284 0.196

± 0.904 0.533 0.498 0.997

±2.302 5.522 2.525 1.464 1.430

0.038 0.000 0.025 0.167 0.176

Coefficient of multiple correlation R = 0.870; Squared multiple R = 0.757; Adjusted R2 = 0.682 P = 0.001 (ANOVA F = 10.106; df = 4±13) Stepwise On Constant RB Lwv

±2.175 2.096 0.931

1.339 0.423 0.490

0.000 0.732 0.281

± 0.975 0.975

±1.625 4.949 1.901

0.125 0.000 0.077

Model R = 0.825; Model R2 = 0.680; Adjusted R2 = 0.637 P = 0.000 (ANOVA F = 15.934; df = 2±15)

1.606), and not correlated (r = 0.00) with the predicted abundance. There is, therefore, a consistency between the observations and the regression model. The stepwise procedure identified rocks and low woody vegetation as the most important predictors of the abundance of wood mice. These two habitat characteristics significantly accounted for 68% of the total variation (p < 0.001). Relations between habitat characteristics and the abundance of Algerian mice The abundance of Algerian mice was explained (R2 = 0.611; p = 0.003) by high woody vegetation, bare ground, and human perturbations (Tab. 3). The residuals in the regression model were low (min = ±1.215; max = 1.124; mean = 0; SD = 0.689), and not correlated with estimated values (r = 0.00). The stepwise procedure revealed that high woody vegetation and bare ground could be used alone to predict the abundance of this species in Great Kabylia.

Discussion In Europe, wood mice are seasonal in their responses to habitat features: in the breeding summer season they seem to disperse ran-

domly throughout the landscape, whereas in the non-breeding winter season they are intimately attached to some habitat components, such as shrubs and hedges (AlcaÂntara and TellerõÂa 1991; Angelstam et al. 1987; Kikkawa 1964; Ouin et al. 2000; Todd et al. 2000). Our results showed that the abundance of wood mice during the breeding season varied greatly with habitat type. Wood mice were mostly captured in plots where rocks covered relatively high proportions (25±50%) of the ground. Khidas and Hansell (1995) reported that, in captivity, wood mice preferably dig burrows beneath a solid box; individuals are thus well protected from predators. In the wild, rocks would play the same role as this solid box. Wood mice may use rocks either to burrow underneath or to shelter in fissures. AlcaÂntara and TellerõÂa (1991) did not identify rocks as an important habitat characteristic for wood mice in the cereal plains of Central Spain. In Great Kabylia the sparseness of grass cover where mice may roam about safely could explain the importance of rocks. Secondly, the abundance of wood mice also increased with shrubs and undergrowth cover (low woody vegetation) as reported by AlcaÂntara and TellerõÂa (1991), Boitani et al. (1985), and Spitz (1974). A study of the

38

K. KHIDAS et al.

Table 3. Estimation of the abundance of Algerian mice by two linear-multiple regression analyses, stepwise off and stepwise on. (See legend in table 1) Variable

Coefficient

Std error

Std coef

Tolerance

t

P (2 tail)

Stepwise Off Constant Hwv BGr HumP

1.667 ±0.568 0.553 ±0.245

0.809 0.164 0.212 0.143

0.000 ±0.696 0.440 ±0.342

± 0.691 0.977 0.698

2.059 ±3.473 2.610 -1.715

0.059 0.004 0.021 0.108

Coefficient of multiple correlation R = 0.782; Squared multiple R = 0.611; Adjusted R2 = 0.528 P = 0.003 (ANOVA F = 7.337; df = 3±14) Stepwise On Constant Hwv BGr

0.629 ±0.414 0.593

0.571 0.145 0.224

0.000 ±0.508 0.471

± 1.989 0.989

1.101 ±2.850 2.646

0.288 0.012 0.018

Model R = 0.728; Model R2 = 0.530; Adjusted R2 = 0.467 P = 0.003 (ANOVA F = 8.442; df = 2±15)

diet of wood mice in Great Kabylia showed that seeds and berries prevail in stomachs ± the consumption of animal prey, mostly insects, was irregular and of less importance (unpubl. data). We suggest that in Algeria the abundance of wood mice during the breeding season is closely related to the availability of seeds and berries which are fully provided by shrubs and undergrowth. In Europe wood mice mainly feed on seeds (Butet 1986; Green 1979; Hansson 1985; Holisova 1960; Obrtel 1975; Watts 1968); and the availability of seeds affects the temporal and spatial distribution of their abundance (Angelstam et al. 1987; Butet 1994; Canova et al. 1994; Green 1979; Kikkawa 1964; Mallorie and Flowerdew 1994; Montgomery et al. 1991). Wood mice are more intimately attached to shrubs and undergrowth in autumn and winter when the food (type, availability, and dispersion) is determinant for their survival (AlcaÂntara and TellerõÂa 1991; Canova et al. 1994; Green 1979; Watts 1969). In Algeria, low productivity of the ecosystems and lack of food supply (Chabi et al. 1995) could account for a similar habitat preference in the breeding season, and probably throughout the year. However, rocks and low woody vegetation explained only part of the variation in the abundance of wood mice. Modification of the natural habitat by human activities, in-

cluding the development of agriculture, also affected the species; yet, the relationship was less clear in this study. Human activities reduce the amount of woody vegetation. Woody vegetation not only provides food, it also represents sites of safety where predation risk is minimised. Furthermore, AlcaÂntara and TellerõÂa (1991) reported that shrubs provide in winter good nesting opportunities for wood mice. Algerian mice were mainly associated with sparse high woody vegetation and a high percentage of bare ground. The highest abundance was observed in agricultural lands. No mice were trapped in matured forests, dense maquis and scrublands, and tree plantations. Analyses of stomach contents showed that Algerian mice in Great Kabylia feed mainly on seeds and fruits found in cultivated fields (unpubl. data). Our results are consistent with the pattern observed in southern European populations of Algerian mice that also live in open habitats (Orsini et al. 1982; Fons et al. 1988). However, in Algeria, as bare grounds and fields quickly become barren in summer, it should be necessary to carry on the study throughout an annual cycle in order to identify the most relevant habitats for this species. Thus, rocks, shrubs, and undergrowth are the crucial habitat characteristics that determine the abundance of wood mice in Great Kaby-

Abundance of Apodemus sylvaticus and Mus spretus in different habitats lia, while Algerian mice are closely attached to agricultural lands and open habitats, at least during the breeding season. In Algeria both species occur only in the northern Mediterranean region of the country where they live sympatricaly (Kowalski and Rzebik-Kowalska 1991). Our trappings showed that these mice are partly syntopic in cultivated lands and open habitats (they were captured on the same trap line in 19% of the overall successful trappings). In Europe wood mice are sensitive to the presence of other smallsized rodents, such as Clethrionomys glareolus, Eliomys quercinus, Mus musculus, Apodemus flavicollis and A. alpicola (Abad 1991; Aeschimann et al. 1998; AlcaÂntara 1991; Amori and Contoli 1994; Boitani et al. 1985; Canova and Fasola 1991; CÏihaÂkova et al. 1993; Dayan and Simberloff 1998; Granjon and Cheylan 1988; Gurnell 1985; Hansson 1985; Henttonen and Hansson 1984); and the patterns of their response to interspecific relationships vary considerably. On the other hand, Algerian mice and house mice Mus musculus domesticus are syntopic in Southern France where they display different patterns of habitat occupancy (Cassaing 1988; Orsini et al. 1982). Syntopy of wood mice and Algerian mice is less well

39

documented. Fons et al. (1988) observed an inverse pattern of spatial occupancy of wood mice and Algerian mice during the regeneration process after the fire in the Mediterranean ecosystems. They reported that both species compete for food; Algerian mice, which have more specific ecological requirements, proved more competitive than wood mice. Our results also showed that the abundance of wood mice is somewhat affected by the presence of Algerian mice. The interspecific relationship between the two species deserves further study.

Acknowledgements This study is a part of a Franco-Algerian exchange research program (ref. 99 mdu 423). We are very grateful to Dr. D. C. D. Happold (Australian National University, Canberra, Australia) who thoroughly commented on the work. We wish to thank also F. Spitz (I.N.R.A., Toulouse, France) and K. Kowalski (Institute of Systematics and Evolution of Animals, Krakow, Poland) for helpful suggestions, and C. Harbusch (ProChirop, Perl-Kesslingen, Germany) for the German abstract. Anonymous referees made suggestions and criticised an earlier draft.

Zusammenfassung Die HaÈufigkeit der Waldmaus Apodemus sylvaticus und der Algerischen Maus Mus spretus (Rodentia, Muridae) in verschiedenen Habitaten im Norden Algeriens Verschiedene Umweltfaktoren bestimmen die HaÈufigkeit von zwei Nagetieren, der Waldmaus Apodemus sylvaticus und der Algerischen Maus Mus spretus. Diese Faktoren wurden in 18 verschiedenen Zonen der Groûen Kabylei (NoÈrdliches Algerien) untersucht. Im FruÈhjahr, wurden Fallen in gerader Linie aufgestellt. Multivariate lineare Regressionen wurden ermittelt. Daraus ergeben sich besondere Beziehungen zwischen Bodendecke und Vorkommen dieser Nagetiere: Die Waldmaus ist staÈrker in steinigen, felsigen und auch mit GestruÈpp bedeckten Gebieten vertreten. Die algerische Maus ist dagegen besonders haÈufig in Gebieten, die arm an GehoÈlzen sind, und in solchen mit kahlem Boden. Durch menschliche AktivitaÈten verursachte StoÈrungen koÈnnen den Bestand dieser Nagetiere ebenfalls stark beeinflussen. Die in dieser Studie aufgefundenen Beziehungen werden in Relation zu Freûgewohnheiten und Feindabwehrverhalten diskutiert.

References Abad, P. L. (1991): Biology of Apodemus sylvaticus in Leon province, Spain. Mammalia 55, 579±589. Aeschimann, J.; Bourquin, L.; Engels, B.; Thomas, C.; Vogel, P. (1998): Comparative winter

thermoregulation and body temperature in three sympatric Apodemus species (A. alpicola, A. flavicollis, and A. sylvaticus). Z. SaÈugetierkunde 63, 273±284.

40

K. KHIDAS et al.

AlcaÂntara, M. (1991): Geographical variation in body size of the Wood Mouse Apodemus sylvaticus L. Mammal Rev. 21, 143±150. AlcaÂntara, M.; TellerõÂa, J. L. (1991): Habitat selection of the Wood mouse (Apodemus sylvaticus) in cereal steppes of Central Spain. Z. SaÈugetierkunde 56, 347±351. Amori, G.; Contoli, L. (1994): Morphotypic, craniometric and genotypic diversification in Apodemus flavicollis and Apodemus sylvaticus. Bool. Zool. 61, 353±357. Angelstam, P.; Hansson, L.; Pehrsson, S. (1987): Distribution borders of field mice Apodemus: the importance of seed abundance and landscape composition. Oikos 50, 123±130. AntuÂnez, A.; Vargas, J. M.; Sans-Coma, V.; Palomo, L. J. (1990): Quelques aspects du cycle biologique de Mus spretus au sud de la peÂninsule ibeÂrique. Vie milieu 40, 196±200. Boitani, L.; Loy, A.; Molinari, P. (1985): Temporal and spatial displacement of two sympatric rodents (Apodemus sylvaticus and Mus musculus) in a Mediterranean coastal habitat. Oikos 45, 246±252. Butet, A. (1986): StrateÂgie d'utilisation des ressources et deÂterminisme des choix alimentaires d'un rongeur polyphage (Apodemus sylvaticus, L.): l'approche eÂnergeÂtique. Acta Oecol., Oecol. Gener. 7, 243±262. Butet, A. (1994): Nutritional conditions and annual fluctuations in Apodemus sylvaticus populations. Russian J. Ecol. 25, 111±119. Canova, L.; Fasola, M. (1991): Communities of small mammals in six biotopes of northern Italy. Acta Theriol. 36, 73±86. Canova, L.; Maistrello, L.; Emiliani, D. (1994): Comparative ecology of the Wood mouse Apodemus sylvaticus in two differing habitats. Z. SaÈugetierkunde 59, 193±198. Cassaing, J. (1988): Structure spatiale de diverses populations de souris ouest-meÂditerraneÂennes (Mus musculus domesticus et M. spretus). Sci. Tech. Anim. Lab. 13, 111±114. Chabi, Y.; Isenman, P.; Benyakoub, S.; Samraoui, B. (1995): Breeding ecology of the North-African blue tit Parus caeruleus ultramarinus in two semi-evergreen oak forests in Algeria. Rev. Ecol. (Terre Vie) 50, 133±140. Churchfield, S.; Hollier, J.; Brown, V. K. (1997): Community structure and habitat use of small mammals in grasslands of different successional age. J. Zool. (London) 242, 519±530. CÏihaÂkovaÂ, J.; ExnerovaÂ, A.; SaÂdlo, J.; Frynta, D. (1993): Many-sided evaluation of the extensive synchronous sampling of small mammals

(Insectivora, Rodentia) in lowland forest. Acta Soc. Zool. Bohem. 57, 1±16. Corbet, G. B. (1978): The Mammals of the Palaearctic Region. A Taxonomic Review. London, Ithaca: British Museum (Natural History) and Cornell Univ. press. Corbet, G. B.; Southern, H. N. (1977): The Handbook of British Mammals. 2nd ed. Oxford, London: Blackwell Scientific Publ. Dayan, T.; Simberloff, D. (1998): Size patterns among competitors: ecological character displacement and character release in mammals, with special reference to island populations. Mammal Rev. 28, 99±124. Fa, J. E.; Shaw, E.; Santana, A. (1992): Habitat associations of small mammals in a southern Spanish fir forest. Mammalia 56, 478±481. Fitzgibbon, C. D. (1997): Small mammals in farm woodlands: The effects of habitat, isolation and surrounding land-use patterns. J. Appl. Ecol. 34, 530±539. Fons, R.; Saint-Girons, M. C. (1993): Le cycle sexuel chez le mulot sylvestre Apodemus sylvaticus en reÂgion meÂditerraneÂene. Z. SaÈugetierkunde 58, 38±47. Fons, R.; Grabulosa, I.; Saint-Girons, M. C.; Galan-Puchades, M. T.; Feliu, C. (1988): Incendie et cicatrisation des eÂcosysteÁmes meÂditerraneÂens. Dynamique du repeuplement en micromammifeÁres. Vie Milieu 38, 259±280. Garcia, F. J.; Diaz, M.; De-Alba, J. M.; Alonso, C. L.; Carbonell, R.; De-Carrion, M. L.; Monedero, C.; Santos, T. (1998): Edge effects and patterns of winter abundance of wood mice Apodemus sylvaticus in Spanish fragmented forests. Acta Theriol. 43, 255±262. Granjon, L.; Cheylan, G. (1988): MeÂcanismes de coexistence dans une guilde de murideÂs insulaires (Rattus rattus L., Apodemus sylvaticus L. et Mus musculus domesticus Rutty) en Corse: ConseÂquences eÂvolutives. Z. SaÈugetierkunde 53, 301±316. Green, R. (1979): The ecology of Wood mice (Apodemus sylvaticus) on arable farmland. J. Zool. (London) 188, 357±377. Gurnell, J. (1985): Woodland rodent communities. Symp. zool. Soc. Lond. 55, 377±411. Hamdine, W.; Poitevin, F. (1994): DonneÂes preÂliminaires sur l'eÂcologie du mulot sylvestre Apodemus sylvaticus dans la reÂgion de Tala Guilef. Rev. Ecol. (Terre Vie) 49, 181±186. Hansson, L. (1985): The food of bank voles, wood mice and yellow-necked mice. Symp. zool. Soc. Lond. 55, 141±168. Harich, N.; Benazzou, T. (1990): Contribution aÁ l'eÂtude de la biologie du mulot (Apodemus

Abundance of Apodemus sylvaticus and Mus spretus in different habitats sylvaticus, rongeurs, murideÂs) dans la plaine coÃtieÁre du Maroc. Mammalia 54, 47±59. Henttonen, H.; Hansson, L. (1984): Interspecific relations between small rodents in European boreal and subarctic environments. Acta Zool. Fennica 172, 61±65. Holisova, V. (1960): Die Nahrung der Waldmaus Apodemus sylvaticus L. im BoÈhmisch-maÈhrischen HoÈhenzug. Zool. Listy 9, 135±158. Khidas, K. (1993): Distribution des rongeurs en Kabylie du Djurdjura (AlgeÂrie). Mammalia 57, 207±212. Khidas, K.; Hansell, M. H. (1995): Burrowing behaviour and burrow architecture in Apodemus sylvaticus (Rodentia). Z. SaÈugetierkunde 60, 246±250. Kikkawa, J. (1964): Movement, activity and distribution of the small rodents Clethrionomys glareolus and Apodemus sylvaticus in woodland. J. Anim. Ecol. 33, 259±299. Kowalski, K. (1985): Annual cycle of reproduction in Apodemus sylvaticus in Algeria. Acta. Zool. Fennica 173, 85±86. Kowalski, K.; Rzebik-Kowalska, B. (1991): Mammals of Algeria. Wroclaw, Warszawa, KrakoÂw: Polish Academy of Sciences and Ossolineum. Long, G. (1974): Diagnostic phytoeÂcologique et ameÂnagement du territoire. I-Principes geÂneÂraux et meÂthodes. Paris: Masson and Cie. Mallorie, H. C.; Flowerdew, J. R. (1994): Woodland small mammal population ecology in Britain: a preliminary review of the Mammal Society survey of Wood Mice Apodemus sylvaticus and Bank Voles Clethrionomys glareolus, 1982±87. Mammal Rev. 24, 1±15. Montgomery, W. I.; Dowie, M. (1993): The distribution and population regulation of the Wood mouse Apodemus sylvaticus on field boundaries of pastoral farmland. J. Appl. Ecol. 30, 783±791. Montgomery, W. I.; Wilson, W. L.; Hamilton, R.; McCartney, P. (1991): Dispersion in the Wood mouse, Apodemus sylvaticus: Variable resources in time and space. J. Anim. Ecol. 60, 179±192. Moreno, E.; Barbosa, A. (1992): Distribution patterns of small mammal fauna along gradients of latitude and altitude in Northern Spain. Z. SaÈugetierkunde 57, 169±175. Obrtel, R. (1975): Animal food eaten by rodents in the reed swamps of Nesyt pond. Zool. Listy 24, 325±334. Orsini, Ph.; Cassaing, J.; Duplantier, J. M.; Croset, H. (1982): PremieÁres donneÂes sur l'eÂcolo-

41

gie des populations naturelles de souris, Mus spretus Lataste et Mus musculus domesticus Rutty, dans le midi de la France. Rev. Ecol. (Terre Vie) 36, 321±336. Ouin, A.; Paillat, G.; Butet, A.; Burel, F. (2000): Spatial dynamics of wood mouse (Apodemus sylvaticus) in an agricultural landscape under intensive use in the Mont Saint Michel Bay (France). Agriculture, Ecosystems and Environment 78, 159±165. Saint-Girons, M. C.; Thouy, P. (1978): Fluctuations dans les populations de Souris, Mus spretus Lataste, 1883, en reÂgion meÂditerraneÂenne. Bull. Ecol. 9, 211±218. Sokal, R. R.; Rohlf, F. J. (1995): Biometry ± The Principles and Practice of Statistics in Biological Research. 3rd ed. New-York: Freeman and Co. Spitz, F. (1974): ReÂpartition deÂtailleÂe des rongeurs en foreÃt. In: Ecologie forestieÁre. Ed. by P. Pesson. Paris: Gauthier-Villars. Pp. 353±357. Spitz, F.; Le Louarn, H.; Poulet, A. R.; Dassonville, B. (1974): Standardisation des pieÂgeages en ligne pour quelques espeÁces de rongeurs. Rev. Ecol. (Terre Vie) 28, 564±578. Todd, I. A.; Tew, T. E.; Macdonald, D. W. (2000): Arable habitat use by wood mice (Apodemus sylvaticus). 1. Macrohabitat. J. Zool. (London) 250, 299±303. Vargas, J. M.; Palomo, L. J.; Palmqvist, P. (1991): Reproduction of the Algerian mouse (Mus spretus Lataste, 1883) in the south of the Iberian Peninsula (Spain). Bonn. zool. Beitr. 42, 1±10. Watts, C. H. S. (1968): The foods eaten by wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) in Wytham woods, Berkshire. J. Anim. Ecol. 37, 25±41. Watts, C. H. S. (1969): The regulation of Wood mouse (Apodemus sylvaticus) numbers in Wytham Woods, Berkshire. J. Anim. Ecol. 38, 285±304.

Authors' addresses: Kamal Khidas, Nora Khammes, and Samia Khelloufi, Laboratoire de Mammalogie, DeÂpartement de Biologie, Universite Mouloud Mammeri, Tizi Ouzou 15000, Algeria; Sovan Lek, Centre d'Etude des SysteÁmes Aquatiques Continentaux, Universite Paul Sabatier, Bat. IVR3, 118 route de Narbonne, F-31062 Toulouse Cedex, France; Stephane Aulagnier, Institut de Recherche sur les Grands MammifeÁres, I.N.R.A., B.P. 27, F-31326 Castanet-Tolosan Cedex, France