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Since virtually
all shrike habitat in Canada lies on private property, landowners
play a vital role in saving this endangered bird.
In Ontario, Manitoba
and Quebec, we’re working with supportive
landowners, as well as researchers, funders and many volunteers,
to bring the Eastern Loggerhead Shrike back from the brink of extinction.
Our efforts are based on a federal recovery strategy developed
in 1996. They include:
• Habitat Stewardship
•
Captive Breeding & Release
• Wild Population Monitoring
•
Radio Telemetry & Geolocators
•
Genetic Studies & Stable Isotope Analysis
And while there’s still a long way to go to reach our goal
of 100 breeding pairs in the wild in distributed among 3-4 populations
in Ontario, the recovery program is making an
impact.
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Shrike habitat
in Canada is shrinking: nearly all of the
original grassland and savannahs have been plowed under or paved
over, while much of the
cattle pasture that provided a substitute
has been abandoned in recent years. At the same time, increasing
development is fragmenting much
of the habitat that remains.
Habitat stewardship is therefore an important part of saving the Eastern
Loggerhead Shrike.
Between 2001 and
2009, we’ve
worked with landowners and volunteers to
restore or improve more than 6800 hectares
of key shrike habitat in Ontario alone. Over half of the wild breeding
pairs in ontario are nesting on sites improved
under the habitat
stewardship program. Wildlife
Preservation Canada coordinates the eastern
loggerhead shrike habitat stewardship program
thanks to funding from the federal Habitat
Stewardship
Program and most recently the Ontario Species
at Risk Stewardship Fund.
Each site is different, but habitat stewardship projects could include:
• Installing or repairing fencing so that abandoned
pastures can be grazed
• Removing cedars and other encroaching brush
• Thinning overgrown grasslands
• Planting shrike-friendly trees and shrubs for
perching and nesting
• Enhancing water sources for livestock
• Fencing for keeping livestock out of wetlands
and streams
In many cases, landowners have benefited from advice and grants to
make their property attractive to Eastern Loggerhead Shrikes.
On Ontario’s Carden Plain/Alvar, a traditional shrike breeding
area, we’ve also helped to spearhead the Integrated
Carden Conservation Strategy.
This multi-stakeholder initiative has brought together naturalists,
government representatives, farmers and ranchers, aggregate producers,
and private landowners. Using a coordinated approach to habitat conservation
and stewardship, it aims to save local species at risk, including the
Eastern Loggerhead Shrike.
Although shrinking habitat is not the only cause of shrike declines,
it is clear that habitat restoration work is making an impact. Today,
more than half the wild Ontario population is nesting on properties
that were enhanced or restored through the stewardship program.
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In 1997, when the wild population
hit a low of only 18 pairs, a captive breeding program was established
for the Eastern Loggerhead Shrike.
A total of 43 wild nestlings
were collected to set up a captive
breeding population. The captive
population was originally held
at two locations: the Toronto
Zoo and Montreal’s McGill
University. The goal was to protect
the genetic diversity of the
population and, if possible,
boost the numbers in the wild
by releasing captive-bred birds.
The initial
results were mixed – not a surprise, since little
was known about how to raise shrikes
in captivity. In 2001, however,
when the captive population reached 100, we launched an experimental
field-breeding and release program
in Ontario that proved very successful.
This program is spearheaded
by Wildlife Preservation Canada.
This approach
allows captive shrikes to raise their young in large wood and
wire-mesh
enclosures located in traditional
shrike habitat. Parents teach the young shrikes
how to fly, hunt and hide from
predators — important
skills if they are to survive in
the wild.
At the end of each breeding season we release approximately 100
of these young birds in Ontario. Since less than five per cent of
wild shrikes typically survive their first year, we need to release
large numbers of captive-bred birds to make an impact.
In 2005 we made history when a captive-bred shrike was spotted
on the Carden Plain, where it subsequently bred with a wild male
and fledged five young. No other captive breeding program for a
migratory bird has achieved this kind of success so quickly, just
four years after the first releases.
Since then,
we have seen more returns each year. In the 2008 season eight
captive-bred
birds were sighted in the wild,
including two released in 2006 — the first time we have
had release birds return to breed in consecutive
years. In total, almost a quarter
(22.2%) of wild pairs confirmed in Ontario in 2008 included a
release
bird. In 2009, an additional four
returns, including a three year
old captive/released bird.
Currently in Ontario we have field-breeding enclosures at two sites
in southern Ontario, as well as over-wintering facilities in Ingersoll,
Ontario, the Toronto Zoo, and African Lion Safari. The Avian Science
and Conservation Centre at McGill University also breeds and releases
captive birds.
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To measure
the success of the recovery effort, we need to track the
number
of Eastern Loggerhead Shrikes in the wild.
To do that, we use colour banding — tiny bracelet-like
rings that are loosely secured around the birds' legs.
Between 1999 and 2006, more than 1,000 adults and nestlings were
banded using different colours to individually identify each bird,
the year of banding and whether it was wild or captive-bred.
If the bird
later shows up somewhere else — whether it's
in another core area in Canada, or thousands of kilometres south
in the United States — the bands will help researchers learn
more about the shrike's behaviour
and migration habits.
Monitoring the wild population is no easy task, since overlooking
only a few pairs means missing a substantial percentage. If you're
a birder and you spot a colour-banded shrike, be sure to report
it by calling us toll-free at 1-800-956-6608.
Currently the
number of shrikes in the wild is still very small — just
31 in Ontario in 2009. The number
of wild pairs in Manitoba is
in the single digits, and no breeding shrikes have been spotted
in
Quebec since 1995.
However, we
have seen some encouraging trends. The population has nearly doubled
since
1997, when only 18 pairs were
left in the wild in Ontario. We’re also seeing shrikes reappear in several
areas. In 2006, for the first time in many years, pairs were spotted
in Ontario’s historic breeding areas of Renfrew and Smiths
Falls and continue to be seen in these areas. In 2008 several birds
on Carden Plain expanded into new territories and early results
for 2009 show that this trend is continuing with two pairs confirmed
breeding in Grey/Bruce where they’d last been confirmed breeding
in 2002.
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Where do Canadian shrikes spend the winter? What route do they take
to get there? What percentage die before they can return to their
breeding grounds?
We are slowly
starting to piece together the answers to these questions, thanks
to genetic
studies and stable isotope analysis and reports of fall and winter sightings (two at Ontario’s
Long Point during fall migration and one in Ohio in March 2007).
To get more detailed information, however, we launched radio-tracking
programs in Ontario and Quebec. By fitting captive-bred shrikes
with tiny radio-transmitters, we can track the birds by car or
airplane.
The transmitters
weigh only 1.4 grams and are attached to the back of the bird
using
a harness. Once it’s on, all that
can be seen is a fine, thread-like antenna extending from the bird’s
tail. Extensive testing has shown they have no physical or behavioural
effects on the shrikes.
To date, we
have learned that more than three-quarters of our captive-bred
birds survive
long enough in the wild to begin migration.
So far, we’ve been able to track them more than 150 km as
they head south, and we’ve learned that 75% of the cative
bred/released shrikes survive to migrate.
Now we’re testing the use of geolocators. These instruments
measure light levels and are now small enough to attach to the
back of a shrike. Because day length on a particular date correlates
to latitude, while the timing of sunrise or sunset correlates
to longitude, this information will let us determine the timing
of migration, the routes shrikes take and the location of their
wintering grounds.
We’ll
need to re-capture the birds to collect the data from the geolocators.
However, with potentially 6.4 per cent of our
captive-release shrikes returning, this is a real possibility.
 Scientific
research is helping us to learn more about shrike population dynamics:
how the genetic make-up of groups of shrikes changes over time,
and how different the genetics are from one group to the next.
To get that
information, we remove a tail feather at the same time as we
band each shrike.
It’s a painless procedure for
the bird, and the feather re-grows
within six weeks.
Using the DNA
in the feather, we can create a genetic profile of the bird.
We can
also track where it has been by
analysing the feather’s stable isotopes — a chemical “signature” created
by the different atomic weights of
elements like carbon and hydrogen
in different geographic areas.
Based on what we know so far, it looks as though individuals from
other groups of Eastern Loggerhead Shrikes join the Ontario populations
each year, bringing new genes into the local gene pool and helping
to maintain shrike numbers here. In turn, some Ontario birds may
join more southerly populations.
It also appears that Ontario shrikes spend the winter throughout
the southern United States, especially along the Mississippi Velley
and watershed system. Further research hopes to confirm specific
wintering grounds and migration routes.
Saving an
endangered species isn’t easy, but recent results
of the Eastern Loggerhead Shrike
Recovery Program show that we are
having an impact.
The number
of shrikes in the wild is consistently
higher than in 2001, when we launched
the captive breeding and release
program as a last-ditch effort to save
this highly endangered bird.
The captive-breeding
and release program has proved highly successful: each year we
release roughly a hundred captive-bred birds, which
are proving they can survive in the
wild, migrate successfully, and return to breed with the wild
population. In 2008, 6.4 per
cent returned to their Ontario breeding
grounds — higher
than the return rate of their wild
counterparts.
Meanwhile,
more than half of the wild population
is nesting on restored or improved habitat,
thanks to the efforts of many landowners,
and we are slowly learning more
about shrike
migration patterns and population
dynamics.
However, with only a
few dozen pairs breeding in the Canadian wild, there’s
still plenty of work to do before we can take the Eastern Loggerhead
Shrike off the endangered list.
Manitoba
Reports
Manitoba
field report 2007
Manitoba
field report 2006
Manitoba field report 2005
Manitoba
update Winter 2004-05
Ontario
Reports
Ontario
field report 2009
Ontario
field report 2008
Ontario
field report 2007
Ontario field report 2006
Ontario field report 2005
Ontario field report 2004
Ontario field report 2003
Quebec
Reports
Outaouais report 2006
Outaouais report 2005
Outaouais report 2004
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