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22001188 SOUTHEASTERN NATURALIST 1V7o(2l.) :1279,3 N–2o9. 72
Avian Feeding on Seed of the Exotic Ornamental
Lagerstroemia indica (Crapemyrtle)
Gary R. Graves*
Abstract - The ornamental plant Lagerstroemia indica (Crapemyrtle) was introduced to
American gardens before 1796, but little is known about its use as a food resource by
avian species. Local wintering populations of Spinus tristis (American Goldfinch), Junco
hyemalis (Dark-eyed Junco), and Haemorhous mexicanus (House Finch) feed heavily on
Crapemyrtle seeds, and I observed 5 additional bird species occasionally extracting seeds
from dehiscent capsules in Fairfax County, VA. Planted and naturalized Crapemyrtle may
be an important food resource for finches and sparrows in southe astern US.
Birds feed on the fruits and seeds of many introduced plant species (Martin
et al. 1951) but surprisingly little has been published on avian use of introduced
ornamental shrubs and trees in eastern North America, with the exception of the
non-native invasive plants Ligustrum spp. (privets), Lonicera spp. (honeysuckles),
and Rosa spp. (roses). Lagerstroemia indica (Crapemyrtle) was introduced
to Charleston, SC, from eastern Asia between 1787 and 1796 by André Michaux
(Cothran 2004, Favretti and DeWolf 1972). Their showy blossoms, attractive bark,
cold and drought hardiness, and ability to grow in a wide range of soil types have
made Crapemyrtle cultivars and hybrids (taxonomy follows ITIS: http://www.
itis.gov) attractive to gardeners, and they are the most widely planted ornamental
shrubs and small trees in public spaces, highway rights-of-way, and private gardens
in the southeastern US (Apgar 1910, Ashe 1908, Chappell et al. 2012). More than
5 million Crapemyrtles were sold by nurseries in 2012 alone (USDA Census of Agriculture
2014). Most cultivars are cold hardy to USDA zone 7 (Daly et al. 2012),
which extends north to Virginia, Tennessee, and northern Arkansas. Crapemyrtle
has been widely planted and naturalized in the Gulf-coast states since the 19th century
(Earle 1902, Harper 1931, Mohr 1901, Sanborn and Scholl 19 08).
Avian feeding on Crapemyrtle seed in North America has been mentioned on
a few gardening websites, but a search of scholarly databases revealed only a
single peer-reviewed paper, which reported Psittacara holochlorus (P.L. Sclater)
(Green Parakeet) feeding on the blossoms and seed in the lower Rio Grande Valley
(Alexander 2016). Here I report the assemblage of avian species that feeds on
Crapemyrtle seed in northern Virginia.
*Department of Vertebrate Zoology, MRC-116, National Museum of Natural History,
Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, and Center for Macroecology,
Evolution, and Climate, Natural History Museum of Denmark, University of
Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø Denmark ; email@example.com.
Manuscript Editor: Doug McNair
2018 Vol. 17, No. 2
Crapemyrtle is commonly used as a landscaping-accent plant in residential
neighborhoods surrounding the study site (~38º46'N, 77º5'W) in suburban Fairfax
County, VA. I monitored birds feeding at a single multi-stemmed specimen (height
= 6 m) that produced ~35,000–45,000 flowers annually. Pollinated flowers produce
brown, ovoid capsules (8–10 mm in diameter) with 6 locules, each containing 4
winged seeds (Fig. 1) arranged in 2 longitudinal rows on either side of a secondary
septum. Capsules begin to dehisce in late October, and most seeds are dispersed
by wind by February. Extrapolated seed mass from a sample of air-dried seeds (n =
200) was ~570,000 per kilogram.
I monitored the focal specimen for a minimum of 30 min per day on a total of
280 days over 5 consecutive winters. Inclusive observation periods extended from
26 December 2013–26 February 2014 (48 observation days), 11 November 2014–
28 February 2015 (95 observation days), 9 November 2015–29 February 2016 (97
observation days), 13 November–19 December 2016 (25 observation days), and 30
November–19 December 2017 (15 observation days). I made repeated scans of the
Crapemyrtle specimen and counted birds observed extracting seeds. I did not count
birds that perched but did not extract seed. I employed daily-high counts (by species)
as proxies for the importance of Crapemyrtle seed in the winter diets of local
populations. None of the birds were banded or color marked, so I was seldom able
to monitor individuals for more than a few minutes.
To illustrate the seasonal pattern in Spinus tristis (American Goldfinch) feeding
visitations, I pooled observations over 5 winters and conducted a distance-weighted
least-square (DWLS) regression of daily-high counts, including days on which
none were observed, on the elapsed time since 31 October. In this procedure,
Figure 1. Left panel: winged seed of Lagerstroemia indica (Crapemyrtle). Right panel:
Spinus tristis (American Goldfinch) feeding on Crapemyrtle seed.
2018 Vol. 17, No. 2
a polynomial regression was calculated for each value of X to determine the
corresponding Y value such that the influence of individual data points on the regression
decreases with distance from the particular X value. I performed analyses
in SYSTAT Version 12 (SYSTAT 2007).
American Goldfinch is a frequent seed predator of Crapemyrtle and was present
on 40% of the observation days and comprised 49% of all birds recorded extracting
seed (Table 1). Singletons or small flocks often spent several hours partially concealed
in dense clusters of seed capsules extracting and consuming seeds. Although
I did not measure handling times or husking proficiency (Zweers et al. 1994), the
bill morphology, body size, and foraging agility of goldfinches appear to be fortuitously
scaled for extraction of seeds from the dehisced Crapemyrtle capsules
(Fig. 1). Goldfinch feeding activity increased steeply in early December, peaked in
mid-December, and gradually declined through late February (Fig. 2).
Table 1. Avian species feeding on Crapemyrtle seed during 280 observation days over 5 consecutive
winters (2013–2017) in Fairfax County, VA.
Number of Total number
days observed of individuals
Common name Scientific name feeding observed
American Goldfinch Spinus tristis (L.) 111 355
Dark-eyed Junco Junco hyemalis (L.) 60 145
House Finch Haemorhous mexicanus (P.L. Statius Müller) 51 144
Northern Cardinal Cardinalis cardinalis (L.) 30 43
House Sparrow Passer domesticus (L.) 14 24
White-throated Sparrow Zonotrichia albicollis (J.F. Gmelin) 3 9
Song Sparrow Melospiza melodia (A. Wilson) 1 1
Pine Siskin Spinus pinus (A. Wilson) 1 1
Figure 2. Daily-high counts of Spinus
tristis (American Goldfinch) observed
extracting seed from capsules of Lagerstroemia
indica (Crapemyrtle) in Fairfax
County, VA. Curved line represents the
distance-weighted least-square regression
of daily-high counts (including zero
values) recorded during 5 consecutive
2018 Vol. 17, No. 2
I also frequently observed Junco hyemalis (Dark-eyed Junco; 21% of observation
days), Haemorhous mexicanus (House Finch; 18%), and Cardinalis cardinalis
(Northern Cardinal;11%) feeding on Crapemyrtle seed. Passer domesticus (House
Sparrow) and Zonotrichia albicollis (Gmelin) (White-throated Sparrow) frequently
perched in the focal tree but I seldom observed them extracting seed from capsules
(only 3% and 1% of observation days, respectively). Feeding activity of all species
was less frequent during significant precipitation events and the day after, perhaps
owing to the increased difficulty of extracting seed from sodden capsules. Seed
retained in capsules decreased rapidly in January and relatively little remained
by late February. Fallen seed was gleaned regularly from the ground by Northern
Cardinals, Dark-eyed Juncos, and sparrows but not American Goldfinches. Crapemyrtle
seed contains alkaloids, phenols, flavonoids, and cardiac glycosides (Ajaib
et al. 2016, Ferris et al. 1971). The extent to which secondary compounds have an
inhibitory effect on avian seed predators is unknown.
Discussion and Conclusions
The horticultural and naturalized Crapemyrtle populations in eastern North
America represent an anthropogenic experiment set in motion by the plant’s introduction
in the late 18th century. Native birds in this region have had more than
a century to discover this novel food resource and learn to extract the winged
seeds from the hexamerous seed capsules. I observed 8 granivorous bird species
extract seed from Crapemyrtle capsules in this study. Fieldwork in other parts of
the introduced geographic range of Crapemyrtle will likely add additional species
to the roster. In any event, I hypothesize that the millions of Crapemyrtles
present on the coastal plain, from Virginia to Texas, are an important winter food
resource for Cardueline finches and sparrows. This introduced ornamental plant
also provides abundant nesting and roosting sites for birds in suburban areas (Small
et al. 2005, Telfair 2010), although there have been no comprehensive field studies
focused on avian use of Crapemyrtle plantings. The leaves, bark, and fruit of
Crapemyrtle contain a number of phytochemicals that make them unpalatable to
herbivorous insects (Ajaib et al. 2016, Chappell et al. 2012, Ferris et al. 1971). As
a result, this plant species hosts relatively few arthropods for avian insectivores.
I thank K.V. Miller and D.W. Tallamy for helpful comments on the manuscript and the
Smoketree Trust for support.
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