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First Observation of Sap Well Use and Maintenance by the Glossy Flowerpiercer (Diglossa lafresnayii) (Thraupidae)

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Abstract

We report observations of a Glossy Flowerpiercer (Diglossa lafresnayii, Thraupidae) using and maintaining sap wells on three shrubs (Asteraceae: Baccharis arbutifolia) on the east slope of the Ecuadorian Andes. The flowerpiercer rotated among shrubs in a trapline fashion, licking and drinking sap and dragging its hooked upper mandible, and possibly also its lower mandible, along the wounds in the Baccharis trunks, presumably to keep sap flowing. This represents, to our knowledge, the first description of sap well use and maintenance in the Thraupidae.
213
SHORT COMMUNICATIONS
The Wilson Journal of Ornithology 121(1):213–215, 2009
First Observation of Sap Well Use and Maintenance by the Glossy
Flowerpiercer (Diglossa lafresnayii) (Thraupidae)
Paul R. Martin,
1,2,4
Frances Bonier,
1,3
and Ignacio T. Moore
3
ABSTRACT.—We report observations of a Glossy
Flowerpiercer (Diglossa lafresnayii, Thraupidae) using
and maintaining sap wells on three shrubs (Asteraceae:
Baccharis arbutifolia) on the east slope of the Ecua-
dorian Andes. The flowerpiercer rotated among shrubs
in a trapline fashion, licking and drinking sap and
dragging its hooked upper mandible, and possibly also
its lower mandible, along the wounds in the Baccharis
trunks, presumably to keep sap flowing. This repre-
sents, to our knowledge, the first description of sap
well use and maintenance in the Thraupidae. Received
12 August 2008. Accepted 14 December 2008.
Plant phloem sap is primarily used in trans-
port of nutrients (predominantly sugars) from
photosynthetic tissues to other regions of the
plant (Freeman 2002, Douglas 2006). Sap is
protected in woody plants by outer cork layers
that include the outer bark of trees and shrubs
(Fahn 1990, Freeman 2002), and by exudates
that impede and eventually stop sap flow from
wounds (Crafts and Crisp 1971). Many spe-
cies have overcome these protections to feed
on phloem sap, including insects (notably He-
mipterans; Douglas 2006), mammals (e.g.,
Goldingay 1987), and birds, most notably sap-
suckers (Sphyrapicus) (Picidae) (Tate 1973,
Eberhardt 2000).
Many bird species across diverse families
feed on sap flowing from pre-existing wounds
(Foster and Tate 1966, Daily et al. 1993, Witmer
1996, Blendinger 1999, Chapman et al. 1999,
Pejchar and Jeffrey 2004, Schlatter and Vergara
2005) or exuded in a modified form by sap-
feeding insects (‘‘honeydew’’) (Reicholf and
Reicholf 1973, Paton 1980, Gaze and Clout
1983, Douglas 2006). However, few bird spe-
cies actively cause and maintain wounds in trees
1
Department of Biology, Queen’s University, King-
ston, ON K7L 3N6, Canada.
2
Yanayacu Biological Station, Cosanga, Napo, Ec-
uador.
3
Biological Sciences 0406, Virginia Tech, 2125
Derring Hall, Blacksburg, VA 24061, USA.
4
Corresponding author; e-mail: pm45@queensu.ca
or other plants to feed on sap. Causing, main-
taining, and attending sap wells has been de-
scribed for several genera of woodpeckers (Pi-
cidae; e.g., Melanerpes, Sphyrapicus, Dendro-
copos, Picoides, Campephilus) (Tate 1973,
Blendinger 1999, Eberhardt 2000, Winkler and
Christie 2002, Schlatter and Vergara 2005), and
in one species each in Psittacidae (New Zealand
Kaka, Nestor meridionalis) (O’Donnell and
Dilks 1989, Morehouse 1997) and Drepanididae
(Akiapolaau, Hemignathus munroi) (Pratt et al.
2001, Pejchar and Jeffrey 2004). Crimson Ro-
sella (Platycercus elegans) have also been ob-
served maintaining sap flow from wounds cre-
ated by a mammal (yellow-bellied glider, Pe-
taurus australis) (Chapman et al. 1999). We de-
scribe sap well use and maintenance by a
neotropical tanager, the Glossy Flowerpiercer
(Diglossa lafresnayii) representing, to our
knowledge, the first description of the behavior
in the Thraupidae.
OBSERVATIONS
We found an adult Glossy Flowerpiercer on
17 October 2006 flying between several Bac-
charis arbutifolia (Asteraceae) shrubs above
Lago Papallacta, Napo, Ecuador (00
22
S,
78
10
W) at 3,350 m in montane Andean
forest. The mean annual temperature in this
area is 8.7
C with mean annual precipitation
of 972.4 mm (climate data from
5kmat
3,300 m; ITM, unpubl. data). The flowerpier-
cer would spend brief amounts of time at each
shrub, scraping wounds on the trunk, and lick-
ing the exuding sap with its tongue before fly-
ing 5–10 m to another shrub. The bird would
return to each shrub every 5–10 min and re-
peat the behavior. Upon inspection, we found
sweet-tasting sap slowly welling in the scars
that were apparently being maintained by the
flowerpiercer through the repeated dragging of
the hook at the tip of the upper mandible (and
possibly also the lower mandible) along the
wounds. Wounds in the shrubs varied in size,
but consisted of a section without bark that
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THE WILSON JOURNAL OF ORNITHOLOGY
Vol. 121, No. 1, March 2009
transected the trunk (usually extending one
third to one half of the way around the small
2–3 cm diameter trunks), in addition to longer
sections that ran parallel to the trunk for 10–
20 cm. Wounds were a few millimeters deep
but, in some cases, appeared worn on one
side. We observed the flowerpiercer drinking
sap and dragging its bill along only one side
of the scar, at the abrupt border of the scar
and bark. The flowerpiercer did not attend the
remaining worn side of the scar and area with-
out bark during our observations.
We identified three shrubs the flowerpiercer
was attending sequentially, possibly attending
additional shrubs out of view before returning
to locations we identified. All three shrubs were
the same species and of similar size (diameter
at breast height 2–4 cm; 3–5 m tall). Wells
ranged from
1 to 2 m above the ground. Ad-
ditional Baccharis arbutifolia shrubs near those
with active wells showed scars that resembled
healed wounds used by the flowerpiercer. The
shrubs being used were
5 m apart, despite the
presence of other similar size Baccharis arbu-
tifolia in closer proximity. At least one addi-
tional Glossy Flowerpiercer was frequently
heard singing and seen in the immediate area of
the sap wells, and was chased from the vicinity
of one of the wells by the one confirmed indi-
vidual that attended the wells. Birds were not
banded, and we could not distinguish or identify
the gender of individuals; we cannot dismiss the
possibility that more than one individual attend-
ed the wells.
We returned to the location on 19 October
2006 and obtained a video of presumably the
same bird at one of the sap wells, allowing
close observation of the bird’s behavior. The
video is available in the Handbook of the
Birds of the World’s Internet Video Collection
(http://ibc.hbw.com/ibc/). The bird first ar-
rived at the wound, and licked and drank sap
that had accumulated in the upper part of the
wound. The bird then dragged its hooked up-
per mandible (and possibly also its lower
mandible) along the wound in the trunk,
working its way down. Twenty-three sec later,
the bird reappeared, dragging its hooked upper
mandible along the same sections of wounded
trunk, dragging downward in independent mo-
tions, hopping up to attend progressively
higher sections of the wounded trunk. Once
the entire wound had been scraped twice, the
bird flew away. We presume dragging of the
hooked upper mandible reopened the wound
to allow continued sap flow. We are unclear
as to the extent to which the lower mandible
was dragged along the wound on the shrub,
and it is possible the lower mandible had an
important role in keeping open the wound. No
other birds were seen attending the sap wells
during video-taped or direct observations at
the site. Our total observation time at the site
over the 2 days was
4 hrs. Weather during
our observation period on both days was cool
and cloudy with brief periods of sun.
DISCUSSION
Flowerpiercers are generally well-known for
their ability to obtain nectar from flowers by
piercing the base of corollas and drinking the
nectar without pollinating the plant (Skutch
1954, Moynihan 1963, Vuilleumier 1969, Isler
and Isler 1999). Flowerpiercers also feed on
nectar by entering the corolla directly (and pol-
linating some flowers), and eat fruit, Mu¨llerian
bodies of Cecropia trees, flower petals, and in-
sects (Skutch 1954; Moynihan 1963; Vuilleu-
mier 1969; Hilty and Brown 1986; Fjeldsa˚ and
Krabbe 1990; Isler and Isler 1999; Rojas-Nossa
2007; R. C. Dobbs, pers. comm.). We regularly
observed Glossy Flowerpiercers feeding on nec-
tar (both by piercing the base of corollas and by
probing the corollas) within 5 km of the sap
wells, but did not observe the focal bird forag-
ing on anything but sap.
Sap wells are often attended (or parasitized)
by other species that consume the exuding sap
(e.g., Foster and Tate 1966, Daily et al. 1993,
Blendinger 1999, Chapman et al. 1999), and
we observed a similar situation at the sap well
we video-taped. We observed 5 insects at-
tending the sap well (including Diptera) dur-
ing 12 min of video, apparently consuming
sap. No other birds were observed attending
the sap well during our limited time of obser-
vation, despite many co-occurring humming-
birds and tanagers in the area. We did not ob-
serve flowerpiercers eating insects that were
attending the sap well.
We suspect this Glossy Flowerpiercer inflict-
ed the original wound in the Baccharis using
the same technique that it used to maintain sap
flow; however, we did not witness the original
formation of the wound. Other species have
been observed secondarily maintaining sap
215
SHORT COMMUNICATIONS
wells they did not create (e.g., Platycercus ele-
gans; Chapman et al. 1999); however, no other
species of vertebrate is presently known to cre-
ate sap wells in montane forests of the eastern
Andes of Ecuador. The distinct wound pattern
used by the Glossy Flowerpiercer is unlike most
others described for sap feeders. The use and
maintenance of this trapline of sap wells rep-
resents, to our knowledge, a novel behavior in
the Thraupidae.
ACKNOWLEDGMENTS
We thank James Law, Patricio Pillajo of the Fundacio´n
Terra for helping with plant identification, and Rob Dobbs
for sharing unpublished observations of flowerpiercers
feeding on Cecropia. We thank P. G. Blendinger, C. E.
Braun, and an anonymous reviewer for helpful comments
on the manuscript. We acknowledge funding from Vir-
ginia Tech Advance postdoctoral fellowship (FB), Na-
tional Science Foundation IOS 0545735 (ITM), National
Science Foundation International Research Fellowship
OISE-0700651 (FB), Natural Sciences and Engineering
Research Council of Canada (PRM), and a Baillie Family
Endowment (PRM).
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The diet of Cedar Waxwings (Bombycilla cedrorum) is described using records of gut contents collected by the U.S. Biological Survey. Cedar Waxwings eat more fruit than most other Temperate Zone birds, including one of the most frugivorous thrushes, the American Robin (Turdus migratorius; 84 vs. 57% fruit in their annual diets, respectively). Cedar Waxwings are almost exclusively frugivorous in the winter and early spring. During the spring period of fruit scarcity, flowers comprise a large portion of the diet of waxwings (44% of May diet). Cedar Waxwings eat aerial and vegetation-borne animal prey, whereas American Robins eat vegetation-borne and terrestrial prey. The fruits eaten by Cedar Waxwings are characterized by high sugar and low lipid content. American Robins, like other North American thrushes, eat sugary and lipid-rich fruits, suggesting contrasting digestive strategies in waxwings and thrushes. This perspective is reinforced by the correspondence between these birds' diets, the timing of breeding in relation to availability of preferred foods, and flocking patterns.
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Honeyeaters mainly collected manna, honeydew or lerp off the foliage and bark of eucalypts and not insects as has been previously reported. These carbohydrates were more abundant than insects and other invertebrates on the foliage or bark, offered energy rewards similar to those from nectar and were widespread, occurring in many habitats. Manna, honeydew and lerp have chemical compositions similar to nectar and were used as substitutes by many honeyeaters. Honeyeaters shifted feeding sites and showed seasonal movements with changes in the distribution and abundance of these resources and nectar. Manna, honeydew and lerp are important in the ecology of many honeyeaters.