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Sorry, I sent the wrong citation in that last message. At least it
was still somewhat relevant to pollinators! Here's the correct one. <br>
<br>
David <br><br>
Zurbuchen, A., L. Landert, et al. (2010). "Maximum foraging ranges
in solitary bees: only few individuals have the capability to cover long
foraging distances." <u>Biological Conservation</u> <b>143</b>(3):
669-676.<br><br>
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<dd><x-tab> </x-tab>To
preserve populations of endangered bee species, sound knowledge of their
maximum foraging distance between nest and host plants is crucial.
Previous investigations predicted maximum foraging distances of
100-200for small bee species and up to 1100for very large species based
on mainly indirect methods. The present study applied a new and direct
approach to experimentally investigate maximum foraging distances in
solitary bees. One endangered and two common species of different body
sizes, all of which restrict pollen foraging to a single plant genus,
were established in a landscape lacking their specific host plants.
Females were forced to collect pollen on potted host plants that were
successively placed in increasing distance from fixed nesting stands. The
maximum foraging distance recorded for the small Hylaeus punctulatissimus
was 1100 for the medium sized Chelostoma rapunculi 1275and for the large
Hoplitis adunca 1400 indicating that maximum foraging distances at
species level have been underestimated. However, the capability to use
resources on such a large spatial scale applied only to a small
percentage of individuals as 50% of the females of H. punctulatissimus
and H. adunca did not forage at distances longer than 100-225and 300
respectively. This finding suggests that a close neighbourhood of nesting
and foraging habitat within few hundred meters is crucial to maintain
populations of these species, and that threshold distances at which half
of the population discontinues foraging are a more meaningful parameter
for conservation practice than the species specific maximum foraging
distances.<br><br>
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