DOI: 10.5061/dryad.mgqnk98zs
title: Estimates of dispersal propagule loads on woodpecker natural history collection specimens

description: Bird-mediated dispersal is presumed to be important in the dissemination
 of many different types of organisms, but concrete evidence remains
 scarce. This is especially true for biota producing microscopic
 propagules. Tree-dwelling birds, such as woodpeckers, would seem to
 represent ideal dispersal vectors for organisms growing on standing tree
 trunks such as epiphytic lichens and fungi. Here we utilize bird natural
 history collections as a novel source of data for studying dispersal
 ecology of plants, fungi, and micro-organisms. We screened freshly
 preserved specimens of three Finnish woodpecker species for microscopic
 propagules. Samples were taken from bird feet as well as chest and tail
 feathers. Propagules were extracted using a sonication-centrifugation
 protocol and the material obtained was studied using light microscopy.
 Diverse biological material was recovered from all specimens of all bird
 species, from all positions sampled. Most abundant categories of
 discovered biological material included bryophyte fragments, fungal spores
 and vegetative propagules of lichens. Also freshwater diatoms, bryophyte
 spores, algal cells, testate amoebae, rotifers, nematodes, pollen, and
 insect scales were identified. The method developed here is applicable to
 living specimens as well, making it a versatile tool for further research.
 Our findings highlight the potential of bird-mediated dispersal for
 diverse organisms and showcase the use of natural history collections in
 ecological research.
description: Bird specimens were obtained from recent accessions to the
 collections of the Finnish Museum of Natural History (LUOMUS). We sampled
 altogether 15 specimens of three woodpecker species native to Finland
 (<i>Dendrocopos major, Dryocopus martius, </i>and
 <i>Picus canus, </i>five specimens of each species). Bird
 specimens were selected based on collecting date, cause of death, body
 condition and post-accession preparation. Only recently acquired specimens
 that had been removed from their natural setting fast, e.g. due to a
 window collision or bird ringing accident, were chosen to avoid a risk of
 post-mortem contamination. All specimens were in good physical condition
 and had been quickly frozen after collection, wrapped in clean newspaper,
 shipped to the museum and then incorporated into the collections,
 labelled, bagged in airtight plastic bags, and frozen for further study.
 The birds had not been washed or otherwise treated before sampling. Using
 the specimen-specific links in the data, the digitized specimen metadata
 can be accessed. All bird specimens selected for
 analysis were processed as follows. First, the specimens were removed from
 their bags and thawed. This was done to avoid condensation of moisture on
 the thawing birds. Three different cotton swabs were used to sample the
 chest feathers, tail feathers and feet of each bird, respectively. For
 feather sampling, the swab was run proximally multiple times across
 multiple feathers, and in the tail feathers especially any visible dusty
 material attached to the underside of the pin of the feather was targeted.
 Feet were sampled in a circular motion on the underside of the digits,
 including under the claws. In addition, a single top layer chest feather
 and a 2 cm fragment from the tip of one tail feather (rectrice 1 or 2)
 were removed for detailed analysis. Collected cotton
 swabs and feathers were suspended in 500 μl of Milli-Q water in sterile
 1.5 ml Eppendorf tubes. Tubes were vortexed briefly and placed in a
 sonication bath for 3 minutes to dislodge biological material from the
 cotton/feathers. After sonication tubes were again briefly vortexed
 followed by 5 min centrifugation (13 000 rpm). Feathers/swab tips were
 then carefully removed from the tubes with forceps, avoiding disruption of
 the potential pellet. This was followed by 3 min centrifugation (13 000
 rpm), after which most of the supernatant was removed. The remaining
 suspension (10-20 μl) was briefly vortexed, spinned down and inspected and
 photographed under phase contrast microscopy (Leica Microsystems, Wetzlar,
 Germany). Biological material was identified as accurately as possible,
 and the abundances of main categories of propagules encountered were
 roughly estimated. As direct counts were impossible due to the large
 amount of material, the amount of the main three categories were
 semi-quantitatively estimated, ranking from no material to few (1-5) units
 to multiple (5+) units. In the dataset, no material is coded with 0, few
 units as + and multiple units as ++.
description: Digitized specimen metadata can be accessed using using the
 specimen-specific links in the data. As direct counts were impossible due
 to the large amount of material, the amount of the main three categories
 were semi-quantitatively estimated, ranking from no material to few (1-5)
 units to multiple (5+) units. In the dataset, no material is coded with 0,
 few units as + and multiple units as ++.