Aspects of ecomorphology in the five European horseshoe bats (Chiroptera: Rhinolophidae) in the area of sympatry [Elektronische Ressource] / von Christian Dietz

Christian Morgenstern

Informations

• Publié par: eberhard_karls_universitat_tubingen
• Publié le: 01 janvier 2007
• Nombre de lectures: 14
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Aspects of ecomorphology in the five
European horseshoe bats (Chiroptera:
Rhinolophidae) in the area of sympatry






der Fakultät für Biologie
der EBERHARD KARLS UNIVERSITÄT TÜBINGEN

zur Erlangung des Grades eines Doktors
der Naturwissenschaften

von
Christian Dietz
aus Tübingen

vorgelegte
Dissertation


2007


















Tag der mündlichen Prüfung: 14.11.2007
Dekan: Prof. Dr. H. Malot
1. Berichterstatter: Prof. Dr. H.-U. Schnitzler
2. Berichterstatter: PD Dr. B.M SiemersTable of contents 3
Table of contents

Structure of this thesis................................................................................................................ 8
Publication of the results............................................................................................................ 9
Author information and contributions from others .................................................................... 9
References ................................................................................................................................ 10
Chapter 1 - Identification key to the horseshoe bats of Europe ............................................... 15
Chapter 2 - Age classification and assessment of reproductive condition............................... 33
Chapter 3 - Effects of forearm bands on horseshoe bats.......................................................... 62
Chapter 4 - Movements of horseshoe bats in northern Bulgaria.............................................. 84
Chapter 5 - Growth of horseshoe bats and the influence of climate ...................................... 110
Chapter 6 - Wing measurement variations in the five European horseshoe bat species........ 138
Chapter 7 - Comparative wing morphology of five sympatric horseshoe bat species........... 170
Zusammenfassung.................................................................................................................. 220
Veröffentlichung und Eigenanteil .......................................................................................... 233
Danksagung............................................................................................................................ 235
Lebenslauf......... 237
General introduction 4
The study of mechanisms enabling species to coexist in sympatry is one of the most
challenging topics in ecology. Competition avoidance and resource partitioning are of special
interest in species exploiting similar resources. Groups of such species depending on similar
resources are guilds, defined as a community of animals showing a considerable overlap in
their ecology mainly due to a similar way of exploiting the same class of environmental
resources, e.g. the members may use similar feeding or prey capture strategies (Root 1967).
According to the competition exclusion principle, similar species evolve different ecological
niches to reduce or avoid competition (Hardin 1960; Schoener 1974; Wiens 1977). Separation
can be achieved by several mechanisms such as character displacement (Brown and Wilson
1956); selection of different habitats, prey types, foraging times and foraging styles (e.g.,
Aldridge 1986; Jones et al. 1993); morphological variation (Bogdanowicz et al. 1999; Findley
et al. 1972; Van Valen 1965); and differences in sensory ecology (Kingston et al. 2000;
Siemers and Swift 2006).
As animal communities are rarely structured by the limitation of a single resource but mostly
by a combination of many resources with a changing importance in different stages of an
individual’s life, an all-encompassing study on community-level coexistence would be a very
demanding task. In addition, resource availability (e.g., prey abundance) may change a lot
within the course of a year or may differ between years and thus might be unlimited at a
certain time. To unravel all possible causes and mechanisms of coexistence unfortunately is
much beyond the possibilities of a relatively short-termed research project like a PhD-project.
Within my project I focused on the flight-ecomorphology as one possible mechanism
structuring a guild of sympatric bat species. The five species under study belong to the family
Rhinolophidae and can be united in a single guild of ‘aerial insectivore narrow space flutter-
detecting foragers’ (Schnitzler and Kalko 1998, 2001; Schnitzler et al. 2003) on the basis of General introduction 5
the unique combination of echolocation call design, wing morphology, foraging style and
prey consumed.
These 5 European horseshoe bat species (Rhinolophus hipposideros, R. mehelyi, R. blasii, R.
euryale and R. ferrumequinum) are closely-related members of a single genus (Guillén et al.
2003) and have extensive overlap in their distribution in southeastern Europe (Mitchell-Jones
et al. 1999), where they occur in sympatry on the Balkan Peninsula and the eastern
Mediterranean. All of them produce long duration constant-frequency echolocation calls with
a maximum energy concentrated in the 2nd harmonic (Griffin and Simmons 1974; Heller and
von Helversen 1989; Jones and Rayner 1989; Möhres 1953; Russo et al. 2001; Siemers et al.
2005). Horseshoe bats use frequency and amplitude shifts modulated onto the echoes of their
constant-frequency calls by the wing beats of insects as a means of detecting prey (Schnitzler
1983). All European horseshoe bats are similar in several morphological respects, including
short and broad wings with a large wing area giving low wing loading, aspect ratio and tip
shape index (Findley et al. 1972; Norberg 1987; Norberg and Rayner 1987). However, the
European species differ in size and body mass: The average body mass and forearm length of
the lesser horseshoe bat (R. hipposideros) are 6-7 g and 37-42 mm respectively, those of the
greater horseshoe bat (R. ferrumequinum) 20-26 g and 54-61 mm, and those of the 3 medium-
sized species (R. mehelyi, R. blasii and R. euryale) are quite similar (9-14 g and 42-54 mm,
respectively - Schober and Grimmberger 1998; Dietz et al. 2007b). All 5 species catch prey
by “flycatching” from a perch or during patrolling flights close to a cluttered background, and
at least some species may also take prey from the ground (Bontadina et al. 2002; Jones and
Rayner 1989; Russo et al. 2002, Siemers & Ivanova 2004). With the exception of the lesser
horseshoe bat (R. hipposideros), these 5 horseshoe bat species prey predominately on
nocturnal moths (Beck et al. 1989, 1997; Goiti et al. 2004; Valenciuc 1971). The lesser
horseshoe bat (R. hipposideros) is distributed over most of southern and central Europe and
has the northernmost limit of distribution of all rhinolophids in Europe, reaching Ireland, the General introduction 6
Netherlands and Poland (Mitchell-Jones et al. 1999). The species prefers to roost in buildings,
but colonies in the south are also found in caves (Dietz et al. 2007b). The species preys
mainly on small Diptera, Lepidoptera and other small insects, predominately in or close to
forests (Beck et al. 1989; Bontadina et al. 2002; Jones and Rayner 1989). The greater
horseshoe bat (R. ferrumequinum) is found in southern and central Europe as far north as
southern England and Wales, the Netherlands and Poland (Mitchell-Jones et al. 1999).
Breeding colonies in the north are mainly in buildings, in the south predominately in
underground roosts (Dietz et al. 2007b). These bats forage in a wide variety of habitats from
open meadows to parks and woodlands, where they prey mainly on coprophagous beetles and
moths (Beck et al. 1997; Bontadina et al. 1995, 1997; Jones and Rayner 1989; Jones et al.
1995). The ecologies of the 3 medium-sized species are less well known. Their distribution in
Europe is confined to the area around the Mediterranean. The Mediterranean horseshoe bat
(R. euryale) has the widest distribution, extending north to central France, Italy, Slovakia and
Romania; Mehely’s horseshoe bat (R. mehelyi) is found in southern and central Iberia,
southern France, Sardinia, Sicily, Greece and in the Balkans north to Romania; Blasius’
horseshoe bat (R. blasii) is restricted to southeastern Europe from the Adriatic coast over the
Balkans to Greece and Romania (Mitchell-Jones et al. 1999). All 3 species roost mainly in
caves and other underground galleries (Dietz et al. 2007b) and prey predominately on moths
(Goiti et al. 2004; Valenciuc 1971; Whitaker and Black 1976). R. euryale forages mainly in
forests, while R. mehelyi prefers to forage in less densely vegetated habitats of a savannah-
type (Russo et al. 2002, 2005). Habitat preferences of R. blasii remain unknown (Siemers and
Ivanova 2004; Dietz et al. 2007b).
One of the most important mechanisms of character displacement is morphological variation
(Bogdanowicz et al. 1999; Findley et al. 1972; Van Valen 1965). Especially in bats the
morphology of the wings can be regarded as being highly adaptive. Beside its sensory ability
to detect and recognize prey (Siemers and Schnitzler 2004), an insectivorous bat’s ability to General introduction 7
use its environment depends la