An Assessment of the Burrowing
Owl
(Speotyto cunicularia)
Reintroduction in the Thompson-Nicola Region of British Columbia
Abstract (1992-1997)
Almost all endangered species are threatened because their
ecological needs are affected negatively by human interference. A tool that
is increasingly used to restore ecosystems where species have disappeared in particular areas is reintroduction
(Quammen 1996; van Dierendonck and Wallis de Vries 1996). In British Columbia this approach is currently in use to
attempt to restore viable populations of burrowing owls.
The burrowing owl (Speotyto cunicularia) is a small migratory
owl that inhabits prairie ecosystems. This owl differs from others
in that it depends on burrows to reproduce and seek shelter.
In most instances, the owl occupies vacant badger (Taxidea taxus),
coyote (Canis latrans), marmot (Marmota spp.) and ground squirrel
(Spermophilus spp.) burrows. In British Columbia the owl could
be found in the grasslands of the southern interior, although
its range may have stretched as far north as the Cariboo Chilcotin
(Cannings, 1978). However, decades of habitat alteration through
urban and agricultural development, overgrazing, pest management
and natural disturbance suppression resulted in a decline of
several ndigenous species, including the burrowing owl (Howie,
1980). Recent improvements in range management are allowing a
slow recovery of these grasslands and potential habitat is now
becoming available.
The owl was designated a threatened species by the Committee
on the Status of Endangered Wildlife in Canada (COSEWIC) in 1978
(Wedgewood, 1978). The continued decline in owl numbers and shrinking
distribution across North America prompted the Canadian Burrowing
Owl Recovery Team to recommend an uplisting to the COSEWIC status
of endangered. On April 3, 1995, the burrowing owl was officially
listed as an endangered species across Canada.
In British Columbia the owl was designated as endangered as
early as 1978. As a result of this listing, the Ministry of Water,
Land and Air Protection, Lands, and Parks (WLAPLP) launched a
recovery program to restore the population of burrowing owls
in BC. One attempt involved the translocation of burrowing owl
families from the Moses Lake area in Washington to Oliver, B.C.
in the Okanagan. This particular project enjoyed limited success
and monitoring efforts were halted in 1994 (O. Dyer personal
communication). In view of these results, a second attempt was
initiated in 1989, this time a reintroduction effort was developed
with its center in Kamloops. Two captive breeding facilities
were constructed (Kamloops and Vancouver). Since 1992, 108 owls
have been released into the wild. These in turn have successfully
fledged thirty young.
Phase 1 of the project consisted of identifying the potentially
important factor(s) that would improve the probabilities of a
successful reintroduction. The successive reintroductions of
burrowing owls since 1992 has provided valuable information regardless
of their independent successes, since ecological information
on this species in B.C. is limited. A number of release and monitoring
approaches have been taken, and knowledge gained in each of those
years has been applied to subsequent releases. In essence, this
exercise is a continuous learning process with improvements made
each year to maximize the probabilities of survival and reproduction
of released owls.
Objectives
The overall objective of the burrowing owl reintroduction program
is to reestablish populations of burrowing owls in three geographical
locations within the Thompson-Nicola Region in accordance with
the mandate of the B.C. Ministry of Water, Land and Air Protection,
Lands, and Parks. The particular goal of the first phase was
to discern potentially significant factors that would guide
future management strategies.
Specifically, the goals were to:
Assess the characteristics of grassland habitats in present and
future release sites in terms of their potential to support
breeding populations of burrowing owls;
Monitor movements and behavior patterns of burrowing owls;
Increase the number of existing burrows and enhance historical
burrowing owl habitats where possible;
Determine the most appropriate release method that will increase
reproductive output and minimize predation-associated mortality;
and,
Increase public awareness and educate local resource users of
matters concerning the burrowing owl.
The specific objectives reflected the need of a thorough understanding
of the ecological needs of the burrowing owl, which includes
knowledge of habitat, prey, and commensal* requirements, all
of which were virtually unstudied in British Columbia (Bryant
1990; Leupin and Low 1996).
*defined as the instance where one organism (the burrowing mammal)
provides resources or a home to another organism (the burrowing
owl) and where the former suffers no tangible ill-effects (Begon
et al 1990).
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