Apidologie (2013) 44:90–99
* INRA, DIB and Springer-Verlag, France, 2012
DOI: 10.1007/s13592-012-0159-4
Original article
Movement patterns of solitary bees in a threatened
fragmented habitat
Achik DORCHIN1,2 , Ido FILIN1 , Ido IZHAKI1 , Amots DAFNI1,2
1
Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mt.
Carmel, Haifa 31905, Israel
2
Institute of Evolution, University of Haifa, Mt. Carmel, Haifa 31905, Israel
Received 10 January 2012 – Revised 21 June 2012 – Accepted 12 July 2012
Abstract – Fragmentation and loss of natural habitats are major threats to many bee species. Large, longdistance flying bees are predicted to be more efficient in utilizing resources and at the same time may function
as important pollinators in a fragmented landscape. Using mark-recapture experiments, this study evaluates the
movement of bees belonging to the “large, long-tongue” guild in a threatened, fragmented habitat. Bee
movement between the sampling plots was limited, despite high recapture proportions within the plots. A
maximum likelihood model has estimated a high degree (60 % of all marked bees) of site fidelity to the source
plots and a mean traveling distance of 357 m for the bees that left the plots. Additional observations on the
bees’ foraging behavior suggest that some anthophorine bee species can be important pollinators in the studied
habitat. We suggest that the bees’ site fidelity and flower constancy are the main causes for their observed
conservative movement pattern.
solitary bees / habitat fragmentation / movement patterns / foraging behavior / site fidelity
1. INTRODUCTION
Loss and fragmentation of natural habitats are
main drivers to the decline of communities and the
diversity of bees (Biesmeijer et al. 2006; Kearns
and Inouye 1997; Kearns et al. 1998; Potts et al.
2010; Winfree et al. 2009) as well as to the plants
that they pollinate (Aguilar et al. 2006). The
effect of fragmentation on different bee species
depends on their ecological traits (Cane et al.
2006; Krauss et al. 2009; Steffan-Dewenter et al.
Electronic supplementary material The online version
of this article (doi:10.1007/s13592-012-0159-4) contains
supplementary material, which is available to authorized
users.
Corresponding author: A. Dorchin,
adorchin@campus.haifa.ac.il
Manuscript Editor: James Nieh
2006; Westrich 1996; Williams et al. 2010) and is
found to be significantly negative on specialized
species, such as parasites and floral specialists
(oligoleges), and also on other solitary bees (Cane
et al. 2006; Krauss et al. 2009).
Higher species’ vagility may permit the utilization of suitable habitat in fragmented landscapes
(Westrich 1996) and, on the other hand, can have
important consequences on local plant populations
via bee contribution to cross pollination (Aizen
and Feinsinger, 2003). Therefore, bee foraging
ranges and patterns can be important characters in
fragmented habitats. Foraging ranges of bees
directly correlate with bee body size (Gathmann
and Tscharntke 2002; Greenleaf et al. 2007).
Thus, large (>10 mm), long-flying bees that can
forage over several km (e.g., Xylocopa, Pasquet et
al. 2008; Anthophora, Rau 1929) are more likely
to move between various habitat fragments (Beil
Solitary bee movement in a fragmented habitat
et al. 2008; Cane 2001; Steffan-Dewenter et al.
2006), but foraging distance is subject to
interspecific and even intraspecific variation
(see in Walther-Hellwig and Frankl 2000).
However, small (6–10 mm) solitary bees have
generally performed shorter foraging ranges of
only 150–600 m (Gathmann and Tscharntke
2002; Zurbuchen et al. 2010b).
Despite the above considerations, potentially
long flight ranges cannot always predict the
movement of bees in a fragmented landscape
(Zurbuchen et al. 2010c). Alternatively, bee
movement patterns may largely depend on their
foraging behaviors. For example, the females of
Apis, Bombus, and some Anthophora species are
floral generalist (polylectic), but nevertheless
present ‘flower constancy’, i.e., they exhibit floral
preference to some degree, and they usually
follow a constant spatial pattern. Furthermore,
these species display weaker floral specificity
while foraging for nectar (Cane and Sipes 2006;
Eickwort and Ginsberg 1980). It is therefore
expected that the movement of these species will
follow the spatial distribution of their favored
food plants. Optimal foraging theory suggests a
mechanism of foraging behavior based on energetic considerations and predicts that bee foragers
are not likely to regularly commute long distances
unless the resources within a given patch of
flowers are poor. This behavior was observed in
the field in social Bombus workers (Pyke 1978).
The present study explored the movement
patterns and behaviors of solitary bees belonging
to the ‘large, long-tongue guild’ (Dafni and
O’Toole 1994, see also in “Methods”), viewed
as potentially important pollinators in a threatened, fragmented habitat in Israel. The specific
objectives of the study were (a) to study and
estimate movement patterns of pollinator bees in
a fragmented landscape and (b) to characterize
their foraging behaviors through observations on
flower visitation. We hypothesized that (a) the
studied bees, being generalists and long distance
flying species, will be able to cross unrewarding
landscape matrix and move between habitat
fragments and (b) bee species will differ in their
movement pattern, based on specific foraging
behavior (flower visitation).
91
2. METHODS
2.1. The sandy-gravel habitat, study area,
and species
The study was performed within a rural landscape
of the Sharon coastal plain in Israel, comprising a
mosaic of natural, abandoned (seminatural), and
actively managed agricultural land use. The study
sites were small fragments (12,000–315,000 m2) of
the sandy-gravel (Kurkar) habitat, characterized by
highly diverse bee fauna and plant flora (overall ∼190
and ∼180 species, respectively, authors’ unpublished
data) and by high floral endemism (about 24 plant
species, Shmida 1984). This unique habitat, which
previously formed a thin belt along the central coast
(6–8 km wide, MAPI 1995), had already been
reduced to 1 % of its estimated original area by the
early 1980s (Polak 1984) and, to date, is threatened
by ongoing intensive development and urbanization
processes.
The studied bees belong to the ‘large, long-tongue
guild’ (Dafni and O’Toole 1994), which are large
species [body length >12 mm, mainly belonging to
the tribes Eucerini and Anthophorini (Apidae)] and
capable of long-distance flight (Greenleaf et al.
2007). These bees are also generalists in terms of
exploiting nectar and pollen resources (see bee
visitation data in Appendices 1 and 2 in the supplements, though accurate determination of the female’s
pollen load is beyond the scope of the present study).
Having long mouth parts (proboscis >6 mm), they
can obtain nectar from a wide variety of plant
species, including tubular flowers as well as openaccess flowers (Eickwort and Ginsberg 1980) and
therefore may contribute to the pollination of a wide
variety of plant species within a fragmented habitat.
2.2. Experimental design
In order to follow the movement of the bees, we
performed a series of mark-recapture experiments in
three study sites, each comprising several natural or
moderately disturbed habitat fragments where a
relatively high diversity of bees was found in
preliminary surveys (authors’ unpublished data). In
each of the study sites that we marked sampling plots,
each plot representing a separate habitat fragment
92
A. Dorchin et al.
(see experiments’ description below). We marked the
bees using fluorescent powder (Bio Quip Products
Inc., USA) mixed with nontoxic, water-soluble glue.
Different colors in each sampling plot allowed us to
determine the movement of the bees between the
plots. Although laborious and distance-dependent, the
mark-recapture method suited our purposes insofar as
it allows the direct tracking of individuals without
manipulation and with minimum intervention.
In each of the experiments, the bees were sampled
by the same person for comparable periods of time in
each of the sampling plots. All of the bees encountered (both males and females) were caught using
insect nets, either while visiting ‘focal plants’ (see
below) or during flight. Dyes were then applied
manually to the dorsal part of the bee thorax, using
plastic inoculating loop sticks (Plate 1). The handling
time was 30–60 s, including determination of the
species with the assistance of a pocket microscope
(45X, Dealextreme, China). Bee recapture and marking were recorded simultaneously, but if individuals
of the same species and sex were found marked, then
they were counted only after 30 s from the moment of
release in order to exclude returning individuals
(especially males practicing territorial behavior). This
marking procedure did not seem to alter the behavior of
the bees, as individuals frequently continued with the
same activity observed prior to our interruption. The
dyes markers soon got dry and were found to remain on
both males and females for at least one week time from
the application (the first day of the experiment), in
accordance sampling trials were designed for no longer
than six consecutive days with at least 10 days intervals
in each of the study sites. All experiments were
performed under favorable conditions for the activity
of bees, namely, on sunny days between 0900 and 1600
when the wind velocity was low (<14 m/s) and the
weather was warm (20–32 °C).
We focused our sampling efforts on bees visiting
selected ‘focal plants’. These were abundant plant
species that are highly rewarding for bees (e.g., species
within the Lamiaceae or Boraginaceae) and which are
believed to have prime importance to the pollinator–
plant system in the habitat (therefore also referred to as
“core species,” Dafni and O’Toole 1994).
Experiments’ description The study site in the TelYizhaq-South Nature Reserve (TYS hereafter, coordinates: 22°14′37″ N, 24°51′55″ E) comprise three habitat
fragments, eastern, western, and northern, the former
being at least two folds larger than the others (Figure 1b).
In order to have comparable replicates we marked in
each of the fragments a square sampling plot with an
equal area of 1,600 m2 and with a distance of 50–70 m
between them. The plots were divided by eroded land
surface, with a maximal altitude difference of 6 m
(Figure 1b). We performed two sampling trials: trial 1
during February 2011 took 2 days and 1–3 h in each
plot. In sampling trial 2, we marked and recaptured bees
simultaneously for five consecutive days, during March
2011, for 2.5 h a day on average in each plot. We
alternately sampled the plots, each day starting at
random in a different plot and then moving to the next.
Additional samplings were performed in two neighboring study sites, sandy-gravel hills in the Sha’ar-Poleg
Nature Reserve (SP hereafter, coordinates: 32°15′30″ N,
Plate 1. E. m. sp. nova. This previously undescribed species (Risch, unpublished data) was found to be the
most abundant pollinator in the TYS site, accounting for 37% of the overall bee abundance in three markrecapture experiments. Left Application of dye markers. Right Male and female in copulation (photographs by
Nicolas J. Vereecken)
93
Solitary bee movement in a fragmented habitat
Fig. 1 Map of the study area
in the Sharon coastal plain
of Israel. The study sites
include seven natural fragments (darkened) of the
threatened sandy-gravel
(Kurkar) habitat, characterized by highly diverse bee
fauna and plant flora. Plots A
and B, in Sha’ar-Poleg Nature
Reserve, and plots C and D,
north to Yaqum represent entire habitat fragments (a);
three additional fragments in
Tel-Yizhaq-South Nature Reserve (b) were sampled using
eastern (E), western (W), and
northern (N), square plots of
equal size. The bees moving
between the sampling plots
were species of the genus
Anthophora and were found
to cover different distances
(marked with white arrows):
1, A. plumipes male, 70 m; 2,
A. agama male, 180 m; 3, A.
rubricrus male, 590 m; 4, A.
plumipes female, 280 m; 5, A.
rubricrus male, 110 m. SW
swamp, AF agricultural field,
FT fruit trees, ES eroded land
surface.
a
Sha'ar-Poleg
Nature Reserve
A
1
4
B
SW
3
AF
C
Yaqum
FT D
2
b
34°50′24″ E) and north to Yaqum (coordinates: 32°15′
19″ N, 34°50′37″ E). Because these sites are located over
2 km away from the TYS site, we treated them as a
separate experimental unite. In each of the sites, we used
two sampling plots, each representing a separate habitat
fragment, along a west to east transect, situated at the
hills’ west- and east-facing slopes. Plots A and B, with
areas of 8,400 and 7,200 m2, respectively, within the SP
site are 40 m apart and are divided by a narrow dirt road
(several meters wide) and disturbed habitat with a
maximal altitude difference of three meters (Figure 1a).
Plots C and D, with areas of 8,400 and 7,200 m2,
respectively, in the Yaqum site, are divided by a private
park planted with fruit trees at a distance of 90 m. The
Tel-Yizhaq-South
Nature Reserve
N
ES
W
E
5
two pairs of plots are divided by the Poleg swamp,
densely covered with common reed (Phragmites
australis [Cav.]) and with introduced Eucalyptus trees,
as well as by an agricultural field strip of seasonal
crops, together comprising a distance of 195 m and a
maximal height difference of 13 m (Figure 1a). We
performed three consecutive sampling trials between
February and April 2011, in which we repeatedly
marked and recaptured individuals at two to four of the
sampling plots simultaneously. Sampling days and
hours varied between the plots according to the
phenology of the bees and the focal plants. Sampling
trial 1 took 4–6 days and 7–10.5 h, sampling trial 2
comprised 1 day and 1.2–3.3 h, and sampling trial 3
94
A. Dorchin et al.
entailed sampling plots A and B for 3 days, each plot
for 3.5 h, and plots C and D for 6 days and 13–18 h.
Statistical analysis In order to evaluate the extent of
bee movement among habitat fragments, we applied
maximum-likelihood estimation to the following statistical model. Derived from our observations (see in
“Results”), we first assume that a fraction f (0≤f≤1) of
all marked individuals exhibit site fidelity to their plot
of origin, and therefore, never (during each sampling
trial) leave the plot in which they were originally
marked. The rest may freely move out of their original
plot and are subsequently distributed according to a
two-dimensional normal distribution, centered at
the plot of origin and having a variance, given by
a second parameter, V (a dispersion pattern
expected, based on random walk of individuals). A
third parameter, q (0≤q≤1), determines the recapture
success within any resampled area or plot (i.e., the
fraction of marked individuals at a given area that are
actually recaptured during a single sampling trial).
We combine the data of all plots into a single
likelihood model, such that each marked individual
contributes a term to the total (log-likelihood function, see Appendix 3 in the supplements for derivations). In that manner, we both increase the power of
our statistical tests (by conducting a single analysis
with the largest possible sample size, i.e., all marked
individuals from all sampling trials in all plots), and
take account of the fates of all marked individuals,
whether recaptured within the plot of origin, within a
different plot, or not recaptured at all.
The site fidelity parameter, f, also plays the role of
measuring how much the actual distribution pattern
of the bees deviates from purely random (normally
distributed). If the hypothesis f=0 can be rejected, the
bees clearly demonstrate a nonzero degree of site
fidelity and are therefore not purely randomly
distributed. For that purpose, we applied a
likelihood-ratio test (Nash and Varadhan 2011,
further details in Appendix 3 in the supplements).
All analyses were done in GNU R v.2.14.1 (R
Development Core Team 2011).
3. RESULTS
In the TYS site, we recorded altogether 271 and
245 bees in the eastern and northern plots,
respectively, and 22 bees in the western plot
(which had lesser sampling effort in sampling trial
2). These were 13 species of the ‘large, longtongue guild’, mostly from the large genus
Eucera. Surprisingly, the most abundant species
appeared to be a new, previously undescribed
species (E. m. sp. nova, Risch, unpublished data;
see Plate 1 and Appendix 1 in the supplements).
The single bee that was recaptured in sampling
trial 1 outside the plot of origin was a male from
the species Anthophora rubricrus Dours moving
from the eastern to the western plot to a distance
of 110 m (Figure 1b). Despite the considerably
high sampling efforts in the eastern and northern
plots (>230 marked bees and >0.25 recapture
Table I. Number of bees marked and recaptured and bee recapture proportions in mark-recapture experiments
(n=5) with large, long-tongue bees.
Sampling plot
SP A
SP B
Yaqum C
Yaqum D
TYS east
TYS west
TYS north
Sampling plot
area (m2)
8,400
7,200
9,600
9,600
1,600
1,600
1,600
Number of marked
bees (range, total)
Number of recaptured
bees (range, total)
Recapture proportion
(range, total)
20–248, 295
12–122, 157
13–95, 199
8–158, 272
43–231, 274
5–16, 21
2–240, 242
1–32, 45
1–21, 24
1–11, 20
4–39, 71
26–62, 88
1–8, 9
1–63, 64
0.05–0.44, 0.62
0.08–0.17, 0.34
0.08–0.11, 0.28
0.17–0.5, 1.04
0.26–0.6, 0.87
0.2–0.5, 0.7
0.26–0.5, 0.76
The sampling plots (n=7) represent natural fragments of a sandy-gravel habitat. SP A/B- Sha’ar-Poleg Nature Reserve, plots
A/B; Yaqum C/D- Yaqum, plots C/D; TYS east/west/north- Tel-Yizhaq Nature Reserve, eastern/western/northern plots
95
Solitary bee movement in a fragmented habitat
Table II. Richness of large, long-tongue bee species, recorded at focal plants with varying abundance in markrecapture experiments (n=3).
Bees visiting similar plants
Bees visiting different plants
Common plants
6 species
Site fidelity
8 species
Uncommon plants
10 species
19 species
Flower constancy
The sampling plots are in Sha’ar-Poleg and Yaqum study sites and represent natural habitat fragments (n=4). Values represent
number of abundant bee species (>5 % of the total bees) that were visiting similar (left cells) as compared to different (right
cells) focal plants in different plots. The visited plants were labeled either as common (found in 3–4 plots, upper cells) or
uncommon (found in 1–2 plots and only in one of the sites, lower cells). Six bee species are suspected to show site fidelity as
compared to 19 species that may demonstrate flower constancy (see “Discussion”)
proportions, see Table I) and the similarity in
species composition (see Appendix 1 in the
supplements), we did not record a single bee
moving between the plots. This result is particularly surprising considering that eroded land
surface with a distance of only 50 m was
separating between the plots and that many
species were marked while visiting the same
species of focal plants in the two plots (see
Appendix 1 in the supplements).
In the SP and Yaqum sites, we marked a total
of 157–295 bee individuals belonging to 14
species, of which 20–71 individuals were
recaptured within each of the four sampling
plots in three sampling trials (Table I). Bee
species that were marked on focal plants in
different sampling plots showed variability in
floral preference. Table II presents the number
of abundant bee species (>5 % of the total bees
marked in each of the sampling plots) that were
recorded at focal plants of varying abundance.
Six bee species were recorded at the same focal
plants, in three or in all four of the sampling
plots, thus occur in both of the sites (and are
labeled as common plants in Table II). These
species typically included: Anthophora plumipes
(Pallas), Anthophora agama Radoszkowski,
Eucera cypria Alfken, and Xylocopa iris (Christ)
(see Appendix 2 in the supplements). Relatively
more (19) species were recorded at different
plants, thus visiting similar plants in only one
plot or two plots of the same site (and are labeled
as uncommon plants in Table II). For example,
Megachile sicula (Rossi) and Eucera w. sp. nova
(Risch, unpublished data) were recorded mainly
at Bituminaria bituminosa (L.) only in the two
plots in Yaqum (see in Appendix 2 in the
supplements).
The recapture proportions within the
sampling plots ranged between 0.05 and 0.5 of
the individuals marked (Table I), but only four
incidents of bees crossing between the plots
were recorded. The crossing bees were all
species of the genus Anthophora, including
males from the species A. plumipes, A. agama,
and A. rubricrus and a female A. plumipes,
covering distances of 70, 180, 590, and 280 m,
respectively (Figure 1).
Estimation of the statistical model described
in “Methods” has revealed a significant and
high degree of site fidelity [f = 0.6 ± 0.036
(estimate±SE); LR statistic=369.9; P<10−6].
The remaining estimated 40 % of individuals,
which may have moved out of their original
plot, are distributed normally with a mean
traveling distance of 357 m [95%CI (200 m,
642 m); obtained from the maximum-likelihood
estimate of V].
Finally, the estimated mean recapture success
within any sampled plot is given by q=0.36±
0.013. That is, on average, 36 % of marked
individuals present at any sampled area are
recaptured. Obviously, realized recapture
proportions would be lower because there
96
A. Dorchin et al.
are marked individuals outside the sampled
plots.
4. DISCUSSION
Movement of bees between the sampling plots
was found to be limited in all of our experiments
and sites. Altogether, we marked about 1,460
solitary bees belonging to 19 species of which 10–
40 % were recaptured at the same plots (the
estimated mean recapture success q=36 %). Despite these relatively high recapture proportions,
we recorded only five individuals crossing
between the plots. The maximum likelihood
model has estimated that 60 % of the individuals
show site fidelity to their original plot. Therefore,
the distribution of bees is far from the one
expected by purely random movements of individuals. Instead, bees tended to stay within their
plots of origin. Our results are in line with those
recorded in mark-recapture experiments with
social species of the genus Bombus (Bhattacharya
et al. 2003 and reference therein). For example,
Bhattacharya et al. (2003) recorded similar
recapture rates to the ones we observed in solitary
bees, with 31 % of the individuals recaptured at
the flower patches of origin and with only three
bees recorded as crossing between sites. As in the
above cited studies, the distances between our
sampling plots (40–195 m) were much smaller
than the flight ranges of the studied species. In
addition, the physical obstructions (e.g., dirt
roads, a field strip 70 m long) were smaller than
the potential barriers previously reported to be
overcome by smaller bee species (Zurbuchen et
al. 2010a). Considering the limitations of the
mark-recapture method, it is possible that we
have underestimated the movement of bees
between the sampling plots. In particular, because
the density of marked bees quickly decreases
with growing distance from the marking point
(e.g., according to a normal distribution, as we
assumed in our statistical model). Nonetheless in
a 5-day sampling trial in the TYS site, in which
the distance between sampling plots was short
(50–70 m) and the sampling effort was high, we
did not observe movement of bees between the
plots. Some solitary bee members of the large,
long-tongue guild were able to move between the
habitat fragments and the maximum likelihood
model estimated their mean traveling distance at
about 350 m. But despite our expectations, the
bees largely refrained from leaving their source
plots. We therefore suggest that high fidelity to
site among the studied solitary bees was the main
factor shaping their foraging patterns. This
same conclusion was reached in the above
cited studies on the foraging behavior of
Bombus (Bhattacharya et al. 2003).
Movement along fixed foraging paths
(Heinrich 1976; Thomson 1996) and frequent
abstention from otherwise penetrable spatial
border lines (Bhattacharya et al. 2003; Kreyer
et al. 2004) were reported as foraging features of
Bombus workers. However, little is known about
the foraging behavior among the myriad solitary
bee species (Michener 2007, except for several
cases like male Euglossine bees since Janzen
1971). The available literature on the foraging
behaviors of different solitary bee taxa has
commonly reported high fidelity to a flowering
patch or tree (Franzén et al. 2009; Gordon et al.
1976; Pasquet et al. 2008), and only when the
location of the nests was manipulated, the
nesting females commuted to the nearest floral
resource (Williams and Kremen 2007). In our
experiments, six species were found to be
foraging on the same focal plants in different
habitat fragments (Table II). These bees, like the
bees in the above cited studies, may present site
fidelity because they could use the same floral
resources in other neighboring plots. In comparison, 19 species were recorded at different focal
plants that were restricted to only one or two of
the habitat fragments (Table II). Considering
these bees as generalist species, they may
demonstrate flower constancy rather than site
fidelity. Interestingly, the bees moving between
the sampling plots were all species of Anthophora (four males and one female), which
largely belong to the group of bees foraging on
the same focal plants in different fragments. The
combination of the two characters, a tendency to
forage on similar plants in different habitat
fragments and the ability to move between
Solitary bee movement in a fragmented habitat
fragments, makes these species potentially important pollinators in a fragmented habitat. The
possible contribution of long distance cross
pollination by these bees can alleviate genetic
and demographic erosion that pose threat to
small plant populations in isolated fragments
(Ellstrand and Ellam 1993, Groom 1998).
The anthophorines moving between plots were
almost exclusively males. Movement patterns and
behaviors of male bees depend mainly on their
searching strategies for a mate (Alcock et al. 1978;
Paxton 2005). Long-distance movement of males
will more likely occur in species in which males
compete for territory than in those where males
practice nonterritorial scramble competition for a
mate. Studies with British populations of A.
plumipes support our results by documenting
territoriality of males and movement between
habitat fragments only when the competition for
mates increases (Stone et al. 1995). Like Stone et
al. (1995), we observed territorial behavior
among male anthophorines that were guarding
specific flowering patches. In contrast, the males
of some eucerine species, such as E. nigrilabris
and E. kilikiae, performed mass swarming
flights, either over flowering bushes or through
the lower vegetation layer, respectively. The
difference in search patterns for mates may
partially explain the movement of male anthophorines between the sampling plots, possibly in
search of territories, as opposed to the movement
of male eucerines. As a consequence, the
potential contribution of some male bees to cross
pollination may be greater than that of females as
already suggested in a study with solitary bees
(Ne’eman et al. 2006).
Surrounding disturbed (seminatural) and agricultural areas are potentially important for bees in
natural habitat fragments by contributing additional food and nesting resources (Westrich 1996).
In our study, some of these areas were found to
be relatively diverse in both bees and plants
(authors’ unpublished data), and therefore, we
assume that most of the bees that were estimated
to leave the source plots (40 % according to the
statistical model) were moving into these areas.
In light of the conservative movement patterns
and behaviors of the bees in our experiments, we
97
suggest that efforts should be made to protect
maximal natural and seminatural habitats for the
conservation of both wild bees and plants. In
addition, the foraging behaviors of the particular
bee species should be considered as a prime factor
for effective conservation management in fragmented habitats. Our results suggest that particularly anthophorine bee species can be important
for the conservation of plants in small isolated
habitat fragments. This may be true for the highly
diverse sandy-gravel habitat along the central
coast of Israel, which is seriously being threatened
by development and fragmentation processes. It
may also be true for many other Mediterraneantype habitats in which large solitary bee (rather
than social, multivoltine) species are primary
native pollinators.
ACKNOWLEDGMENTS
We thank Stephan Rich and Christopher O’Toole
for their help with the identification of bee species.
We also thank two anonymous reviewers for their
contribution to the improvement of this article. This
study was supported by the Israel Science Foundation
(ISF) (grant number 768/08, given to A. Dafni) and
by The Dorothy and Henk Schussheim’s Fund for
Ecological Research in Mt. Carmel.
Schéma des déplacements d’abeilles solitaires dans
un habitat fragmenté et menacé.
Abeille solitaire / fragmentation de l’habitat /
déplacement / comportement d’approvisionnement
/ fidélité au site
Bewegungsmuster von Solitärbienen in einem
durch Fragmentierung bedrohten Habitat
Solitärbienen / Habitatfragmentierung /
Bewegungsmuster / Sammelverhalten/ Ortstreue
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