About the Author
Phil has been a casual birder since his childhood in
England. He attended a birding course given by Jim Grant in
Vernon in the early 1980s and has been a committed birder
ever since. Phil is a forest protection officer and lives with
his wife and two teenage daughters in Williams Lake.
BURDOCK ENTRAPMENT OF A RUBY-CROWNED
KINGLET IN THE CRESTON VALLEY
Linda M. Van Damme
Figure 1. Ruby-crowned Kinglet entrapped on the seed head
of a great burdock plant near Wynndel, BC. 5 April 2004.
(Linda M. Van Damme). BC Photo 3206.
619 - 20th Avenue South, Creston, BC. V0B 1G5
Common burdock (Arctium minus) and great burdock
(A. lappa), members of the sunflower family, are introduced
weeds which are widespread in disturbed land in the
southern interior of British Columbia (Parish et al. 1996).
The invasive plant is well known to farmers and ranchers
who consider it a serious agricultural pest. Seed heads (e.g.,
burs) may cause pain and irritation for domestic grazing
animals, as well as wild mammals, when it becomes lodged
in a mouth, stomach, or on fur and ears. Since the early
1900s burdock has been recognized as a “death trap” for
small birds (Humphreys 1975).
This note describes a Ruby-crowned Kinglet (Regulus
calendula) found entrapped on great burdock in the Creston
Valley, British Columbia. On 5 April 2004, while clearing
a weedy patch on her rural property north of Wynndel,
Judy Winterbottom discovered a Ruby-crowned Kinglet
entangled on a clump of mature dried burdock (Figure 1).
The bird was ensnared by barbed hooklets on the breast,
belly, head, left wing, right leg, and right foot. The bird was
freshly dead suggesting this fatal accident occurred during
spring migration.
It has been suggested that many small insectivorous birds
become entrapped on burdocks while foraging for insect
larvae on the seed heads (Needham 1909). As well, gusty
winds may cause birds foraging in burdock to lose their
balance and become snared (Herzberg and Juhola 1986).
Burdock entrapment of birds in British Columbia is a
rare event but it is probably under reported. Dawe (1974)
reported the death of a Golden-crowned Kinglet (Regulus
satrapa) found by Val McLeod at the George C. Reifel
Migratory Bird Sanctuary in Delta on 4 February 1974. A
dead, ensnared Ruby-crowned Kinglet was discovered by
Bert Brink in the Bull River valley in 1992 (Brink 2004).
2:1 June 2005
The Ruby-crowned Kinglet is not the only animal
to perish from burdock entrapment. Other species from
published literature in North America include: Ruby-throated
Hummingbird (Archilochus colubris), Cassin’s Vireo (Vireo
cassinii), Black-capped Chickadee (Poecile atricapilla),
Red-breasted Nuthatch (Sitta canadensis), Blue-gray
Gnatcatcher (Polioptila caerulea), Northern Parula (Parula
americana), Yellow-rumped Warbler (Dendroica coronata),
Magnolia Warbler (Dendroica magnolia), Common
Yellowthroat (Geothlypis trichas), Pine Siskin (Carduelis
pinus), American Goldfinch (Carduelis tristis), little brown
myotis (Myotis lucifugus), and red bat (Lasiurus borealis).
(McNicholl 1988,1994; Brewer 1994; Nealen and Nealen
2000; Iron 2002; Brink 2004; and Hinam et al. 2004).
Weights for the 15 species listed above range from about
3.5 g (Ruby-throated Hummingbird) to 15.2 g (Cassin’s
Vireo). It appears that animals weighing within this range,
and whose habits include foraging near the ground in plants
and low bushes, are most susceptible to entanglement by
burdock.
Other than burning or herbicide spraying, most types of
mitigation or control is nearly impossible for many weed
species. However, early mowing of burdock, before seed
heads develop, can make a difference at a local level.
Literature Cited
Brewer, A.D. 1994. Blue-gray Gnatcatcher killed by
entanglement on burdock. Ontario Birds 12:115-116.
Brink, V.C. 2004. Burdock, burrs and birds. Discovery
33:24-25.
14
FIRST NEST AND EGGS OF THE CANADA
WARBLER FOR BRITISH COLUMBIA
Dawe, N. 1974. Golden-crowned Kinglet death on
burdock. Murrelet 55:29.
Herzberg, L. and H. Juhola. 1986. (Untitled). Toronto
Field Naturalist 384:25.
Hinam, H.L., S. Sealy, and T.J. Underwood. 2004.
Ruby-throated Hummingbird, Archilochis colubris,
entanglements in burdock, Arctium spp., at Delta marsh,
Manitoba. Canadian Field-Naturalist 118:85-89.
Humphreys, G. 1975. Burdock as a threat to small birds.
Canadian Field-Naturalist 89:326.327.
Iron, J. 2002. Kinglet killer. Ontario Field Ornithologists
Newsletter 20:11.
McNicholl, M.K. 1988. Bats and birds stuck on burdock.
Prairie Naturalist 20:157-160.
_____. 1994. Additional records of birds caught on
burdock. Ontario Birds 12:117-119.
Nealen, H. and P. Nealen. 2000. Ruby-throated
Hummingbird death by common burdock (Arctium minus).
Wilson Bulletin 112:421-422.
Needham, J.C. 1909. Kinglet captured by burdocks.
Bird Lore 2:26.
Parish, R., R. Coupe, and D. Lloyd. 1996. Plants
of southern interior British Columbia. Lone Pine Press,
Edmonton, AB. 463 pp.
R. Wayne Campbell
2511 Kilgary Place, Victoria, BC. V8N 1J6
Finding nests with eggs of ground-nesting wood-warblers
such as the Black-and-white Warbler (Mniotilta varia),
Ovenbird (Seiurus aurocapilla), and Mourning Warbler
(Oporonis philadelphia) is always a challenge and very few
have been discovered in British Columbia (Campbell et al.
2001). The breeding range of the Canada Warbler (Wilsonia
canadensis) in the province is based on observations of five
broods of fledged young often without details of their age.
Developing an accurate breeding chronology, therefore,
requires dates for a significant number of nests and eggs as
well as the known ages of fledglings gathered over a long
period of time.
On 6 July 2003 I accidentally discovered a nest of a
Canada Warbler while trying to count the number of chicks
in a brood of Ruffed Grouse (Bonasa umbellus) about 4
km northeast of Jackfish Lake in the Chetwynd area. The
general habitat consisted of a young mixed-aged stand of
black spruce (Picea mariana), trembling aspen (Populus
tremuloides), balsam poplar (Populus balsamifera), and
white birch (Betula papyrifera) on a gentle forested slope
leading to a lake. The nest itself was in the centre of a 3.4
m tall, very dense shrub patch composed of willow (Salix
sp.), Saskatoon (Amelanchier alnifolia), red-osier dogwood
(Cornus stolonifera), prickly rose (Rosa acicularis) and
fringed with tall grasses and cow-parsnip (Heracleum
lanatum). The nest itself was on the ground among woody
debris and fallen leaves at the base of a small prickly rose
shrub. It contained four well-incubated eggs ascertained by
the “float-in-water” test (see Campbell and Preston 2001).
Later it was discovered that the adult female was the bird
flushed. The male was never seen.
On 8 July Dale Jensen checked the nest and it contained
four naked young. By 17 July the nestlings were ready
to leave the nest and two days later all had fledged. The
following year the nest site and vicinity was visited on six
occasions between 28 May and 29 June. No Canada Warblers
were heard or seen.
The Canada Warbler is probably widely distributed
throughout the Peace River region of British Columbia but
may be restricted to pockets of moist habitats with dense
thickets on gentle slopes and some vegetative ground cover.
Acknowledgements
I am grateful to Sheila Reynolds and Judy Winterbottom
for sharing the kinglet discovery. I wish to thank Martin K.
McNicholl and Jean Iron for providing useful references and
Janice Arndt for her unpublished observation of the Northern
Parula incident. Martin encouraged the writing of this note.
15
Wildlife Afield