Habitat selection and partitioning of the Black-bellied Sandgrouse (Pterocles orientalis), the Stone Curlew (Burhinus oedicnemus) and the Cream-coloured Courser (Cursorius cursor) in arid areas of North Africa

https://doi.org/10.1016/j.jaridenv.2013.02.007Get rights and content

Abstract

Niche theory predicts that coexisting species with similar trophic requirements should demonstrate resource partitioning, particularly where resources are scarce. Conversely, this is not expected between species that do not share primary resources. This study analyses the patterns of spatial coexistence and habitat selection, on two spatial scales, of three species of semidesert regions in Morocco: the Black-bellied Sandgrouse (Pterocles orientalis), the Stone Curlew (Burhinus oedicnemus) and the Cream-coloured Courser (Cursorius cursor). Co-occurrence analysis results point to between-species segregation on a macrohabitat scale. Hotelling's T test of the species-presence data showed a pattern of macrohabitat selection that diverged from habitat availability for the three species with differences among them. Both the classification tree and the pattern of microhabitat selection obtained by model averaging showed scant overlap between the Sandgrouse and the Courser, suggesting habitat partitioning between them on a fine scale. Our results confirm spatial segregation of the three species, especially between species with different trophic strategies: the Sandgrouse versus the Stone Curlew and the Courser. The latter two species were best segregated on a microhabitat scale, supporting the conclusions that macro- and microhabitat selection are major factors in bird community configuration in arid ecosystems and contributing to reduce potential competition.

Highlights

► The three steppe-bird species show a low level of overlap at the macrohabitat scale. ► Granivorous species shows habitat segregation from insectivorous ones at macro and microhabitat. ► Insectivorous species show habitat partitioning only at microhabitat scale. ► Segregation is mainly based on abiotic factors such as topography and surface structure.

Introduction

Habitat selection is a complex process in which organisms actively select between various available resources (Johnson, 1980) with which they can maximise their biological efficiency. The determinants of this choice may be of an evolutionary origin, such as phylogeny, life strategies, locomotory adaptations, and trophic preferences, or may be of a proximal, ecological nature, involving the presence of congeners or other species, anthropic influences or variations in plant productivity (Cody, 1985; Fretwell and Lucas, 1970; Morris, 2003; Rosenzweig, 1981). Habitat selection, as an important axis of a species' ecological niche (Rosenzweig, 1981, 1987), is a hierarchical process in which the pattern detected is frequently dependent on the scale of analysis employed (Kotliar and Wiens, 1990). It varies from the macrohabitat scale, defined as the area in which an organism performs most of its biological activities (Morris, 1987), to the microhabitat scale, a term that refers to the structural characteristics of the locations that are actually perceived and selected by an organism (Morales and Traba, 2009; Morales et al., 2008).

Habitat selection in birds, particularly in prey and ground-dwelling species, has been found to be dependent to a large degree on vegetation structure, which is a good indicator of the compromise made between factors linked to individual survival and those that facilitate reproduction (Cody, 1985; Delgado and Moreira, 2000; Morales and Traba, 2009; Morales et al., 2008). In arid environments without plant cover or with sparse dwarf shrubs, birds are often constrained by abiotic factors (Palomino et al., 2008). Thus, substrate type and slope have been shown to be key factors in habitat selection by cursorial species, such as the Cream-coloured Courser (Cursorius cursor; Palomino et al., 2008), the Houbara Bustard (Chlamydotis undulata; Carrascal et al., 2008a) or the Dupont's Lark (Chersophilus duponti; Garza et al., 2005; Seoane et al., 2006), which are chiefly associated with their locomotory requirements (Palomino et al., 2008; Seoane et al., 2006).

The present study analyses the patterns of spatial co-occurrence and habitat selection and partitioning on two spatial scales of three bird species of semi-desert areas in Morocco: the Black-bellied Sandgrouse (Pterocles orientalis; Linnaeus, 1758), the Stone Curlew (Burhinus oedicnemus; Linnaeus, 1758) and the Cream-coloured Courser (C. cursor; Latham, 1787).

The Black-bellied Sandgrouse is a medium-sized granivore that is characteristic of the steppes and pseudo-steppes of South Western Europe, North Africa and the Middle East (BirdLife International, 2004). It is known to select open and sparsely-vegetated habitats (De Juana, 1997). In Morocco, it inhabits arid and semi-arid plains and upland plateaus where the vegetation is dominated by Artemisia, Haloxilon, Stipa and Ziziphus (Thêvenot et al., 2003). Overall, it is regarded as uncommon in Morocco; however, it is locally common in a few regions of the southwest (Thêvenot et al., 2003). To the knowledge of the authors, there are no quantitative estimates of the Moroccan population (BirdLife International, 2004), but the species is globally classified as of ‘Least Concern’ (IUCN, 2012).

The Cream-coloured Courser is a medium-sized insectivore that chiefly inhabits the Sahel, from Morocco to the Middle East, although it occasionally appears in Europe (Del Hoyo et al., 1996; Urban et al., 1986). It is a relatively common resident in Morocco where it occurs in similar habitats to those of the Sandgrouse in the north of the country (Thêvenot et al., 2003). Information on its distribution, abundance or habitat selection in Morocco is scarce or non-existent (Thêvenot et al., 2003). It is globally classified as of ‘Least Concern’, although its population has not been quantified to date (IUCN, 2012).

The Stone Curlew is a medium-sized insectivore that has an extensive though fragmented Palearctic distribution (De Juana et al., 2004). It frequents open and treeless areas, such as grasslands, arid pastures and both natural and artificial steppe lands (Hume, 1996). It exhibits wider habitat preferences than the other two species in Morocco, as it also occurs in river valleys and areas vegetated with Argan bushes (Argania spinosa) and it is common in cultivated areas, such as fallows, tilled land and grain fields (Thêvenot et al., 2003). The global population range is estimated to be 130,000–310,000 individuals (BirdLife International, 2004), although the Moroccan population has not been quantified to date. The species is globally classified as of ‘Least Concern’ (IUCN, 2012).

The Stone Curlew, which has a short straight bill, is a surface and mainly crepuscular and nocturnal feeder (Cramp and Simmons, 1983) with a diet based mainly on arthropods, secondarily on mollusks, and occasionally on small mammals (Giannangeli et al., 2004 and references therein). By contrast, the Cream-coloured Courser with its relatively long, pointed, and down-curved billfeeds primarily during the daytime by walking or running across the ground and pausing to capture prey. It may also catch insects in-flight or dig for food with its beak (Cramp and Simmons, 1983). Therefore, inter-specific competition for food is probably low and limited by the nomadic movements of these two bird species, suggesting that both species share macrohabitats on a broad-scale while demonstrating different microhabitat selection on a fine-scale.

Analyses of habitat selection at different spatial scales may show whether an organism positively selects from available macrohabitats (coarse scale) or whether it selects among specific microhabitats that are available within each macrohabitat (fine scale) (Palomino et al., 2008; Traba et al., 2010). The latter would suggest that species with similar trophic requirements that have long coexisted, such as the two insectivores (the Stone Curlew and the Courser), will select different microhabitats, as a result of the ‘ghost of past competition’ (Connell, 1980; Rosenzweig, 1981, 1987), to facilitate coexistence (Rosenzweig, 1981) and avoid competition in environments where resources are scarce. The former, macrohabitat selection, suggests that a species such as the Sandgrouse, a granivore that is less cursorial than both insectivores and must fly relatively long distances to a water source each day, has different ecological requirements, which lead to the selection of different macro- and microhabitats.

The following predictions arise from the above hypotheses: 1) the species with different trophic requirements (the Black-bellied Sandgrouse) will show spatial segregation at the macrohabitat scale (i.e. different macrohabitat selection); and 2) co-occurring species on a macrohabitat scale (the Cream-coloured Courser and the Stone Curlew) that are also both insectivores will show differences in microhabitat selection that guarantee non-competition for resources, particularly within resource-poor habitats such as the arid environments studied.

Section snippets

Study areas

Observations were made in four study areas in the vicinity of Marrakech: Guemassa (8°22′58″W, 31°29′5″N; 510 m above sea level); Harbill (8°1′43″W, 31°47′46″N; 472 m asl); Mzoudia (8°41′30″W, 31°40′44″N; 281 m asl); and Sidi Chiker (8°40′12″W, 31°47′34″N; 236 m asl).

The climate is Mediterranean, with cool, wet and overcast winters, hot, dry and clear summers, and occasional rainy storms during July and early August. The mean annual rainfall is 240 mm with almost 80% occurring from October to

Results

Species densities estimated in the four study areas are given in Table 2. None exceeded 1.30 birds/10 ha. The Black-bellied Sandgrouse was the most abundant species (0.68 ± 1.32), followed by the Cream-coloured Courser (0.51 ± 0.94) and the Stone Curlew (0.14 ± 0.34). The highest densities of Sandgrouse and Courser were observed at Guemassa, whereas Mzoudia was observed to have the highest Stone Curlew density.

Discussion

The results presented here point to the coarse-scale spatial segregation of the three study species, which is most clearly seen between those species with different trophic requirements, i.e. the Sandgrouse (granivore) compared with the Stone Curlew and the Courser (insectivores), which may be attributed to differential macrohabitat selection (coarse-scale habitat selection). The microhabitat overlap (fine-scale habitat selection) for the Sandgrouse and the insectivores was scant, even within

Acknowledgements

This study was funded by the Agencia Española de Cooperación Internacional via a project within the PCI programme (Code A/3895/05). The Terrestrial Ecology Group (TEG) is partly supported by the REMEDINAL-2 research network of the Comunidad de Madrid-European Social Fund (Code S-2009/AMB/1783). We would like to thank M. Aourir for his help in the field work.

References (50)

  • L.M. Carrascal et al.

    Preferencias de hábitat, estima y tendencias poblacionales de la Avutarda Hubara (Chlamydotis undulata) en Lanzarote y La Graciosa (Islas Canarias)

    Ardeola

    (2006)
  • L.M. Carrascal et al.

    Habitat use and population density of the houbara bustard Chlamydotis undulata in Fuerteventura (Canary Islands)

    African Journal of Ecology

    (2008)
  • L.M. Carrascal et al.

    Density bias estimations with fixed-strips line transects in dry open-country environments in the Canary Islands

    Animal Biodiversity & Conservation

    (2008)
  • M.L. Cody

    Habitat Selection in Birds

    (1985)
  • J.H. Connell

    Diversity and the coevolution of competitors, or the ghost of competition past

    Oikos

    (1980)
  • S. Cramp et al.
    (1983)
  • M.A. Daley et al.

    Muscle force–length dynamics during level versus incline locomotion: a comparison of in vivo performance of two guinea fowl ankle extensors

    Journal of Experimental Biology

    (2003)
  • E. De Juana

    Family Pteroclidae (Sandgrouse)

  • E. De Juana et al.

    Fluctuaciones relacionadas con la precipitación en la riqueza y abundancia de aves de medios esteparios mediterráneos

    Ardeola

    (2005)
  • E. De Juana et al.

    Alcaraván Común, Burhinus oedicnemus

  • J. Del Hoyo et al.
    (1996)
  • R.L. Dellinger et al.

    Habitat partitioning of four sympatric thrush species at three spatial scales on a managed forest in West Virginia

    The Auk

    (2007)
  • P.N. Ferns et al.

    Effects of raptors on the activity of Sandgrouse

    Journal of Raptor Research

    (1994)
  • S.D. Fretwell et al.

    On territorial behavior and other factors influencing habitat distribution in birds I. Theoretical development

    Acta Biotheoretica

    (1970)
  • V. Garza et al.

    Home range, territoriality and habitat selection by the Dupont's lark Chersophilus duponti during the breeding and postbreeding periods

    Ardeola

    (2005)
  • View full text