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Nestbox
Program at the
San Joaquin Wildlife Sanctuary
in Irvine
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by
Christine Tischer
SJWS Nestbox Program Manager |
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| History |
| The nestbox program
started as a mere handful of boxes at the San Joaquin Wildlife
Sanctuary in the late 90’s. It was established as a
joint program between Irvine Ranch Water District (IRWD) and
Sea and Sage Audubon. IRWD installed the boxes as part of
a mitigation requirement for their water reclamation plant.
Sea and Sage Audubon provides the expertise of several volunteers
to monitor and maintain the boxes. Monitoring of the boxes
began in the year 2000. Hardly any vegetation was associated
with the ponds at the start of the program in 2000. Since
that time, restoration activities have greatly improved the
landscape at the marsh while providing more foraging, overwintering,
and nesting habitat for numerous bird species. Boxes are shifted
on a yearly basis to account for vegetative growth and to
optimize productivity. |
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| Monitoring |
| Volunteers monitor
the boxes on a weekly basis during the breeding season (March
through July). They count the number of nests, eggs, chicks,
and number of chicks that fledge (successfully leave the nest).
They also ensure that boxes are in workable condition, trim
vegetation from around the boxes, protect the birds from ants,
mites, and other predators, and record banding information.
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| Banding
Program |
| The majority of
Tree Swallow chicks were banded as part of the Tree Swallow
Nesting Project, a Ventura-based non-profit organization.
Chicks are banded at 10 days of age and fledge between 21
and 28 days of age. A small aluminum band is placed around
one leg of each bird by a certified bander. Each band is engraved
with a unique series of numbers, typically 4 numbers in the
top row and 5 numbers in the bottom row. The band numbers,
age of bird when banded, and banding location are reported
to the U.S. Geological Survey (USGS), who then inputs the
information into a nationwide database for banded birds. Valuable
information can be collected when birds are found or recaptured
later in life. If you ever find a banded bird, record the
band sequence from top to bottom and from left to right. Note
the leg the band is on, and whether it’s the bird’s
left or right leg. Some birds can be color banded with one
color band, multiple color bands, or a combination of color
and metal bands. Again, note the leg it occurs on and the
sequence of the color bands from closest to the body to furthest
from the body (for example, blue over red or metal over yellow).
Don’t forget to note the type of bird if you are able
to identify it or at least a description of the bird and its
size. This information can be called into the USGS Bird Banding
Hotline at 1-800-327-BAND. You will receive an official certificate
in the mail describing where and when the bird was banded
and you’ll be providing invaluable data for that bird
species. |
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| 2000-2009
Nestbox Results |
| Although the nestboxes
are appropriately sized for a number of cavity-nesting bird
species, the boxes are used almost exclusively by Tree Swallows
(Tachycinita bicolor). According to the Atlas of Breeding
Birds, Orange County, California (Gallagher, 1997), no successful
Tree Swallow nesting was confirmed during atlasing years (1985-1990).
Tree Swallows typically nest in tree cavities as indicated
by their name. However, this species and other cavity nesting
species were on the decline as breeding birds in Orange County
because of the loss of old growth tree groves to residential
and commercial development. Luckily, Tree Swallows readily
adapt to artificial nestboxes. Unlike Tree Swallows on the
east coast that are known to have only one brood per season,
Tree Swallows in southern California can have two broods in
a single nesting season. The number of second broods is typically
lower and can likely be linked to a number of factors including
weather, food availability, and 1st brood nest failure/success
to name a few. The program has been
highly successful in bringing theTree Swallow back to the
County of Orange as a breeding bird species In addition to
Tree Swallows, a few Western Bluebirds (Sialia mexicana) and
House Wrens (Troglodytes aedon) have claimed a box or two
over the years. The results of the ten nesting seasons
from years 2000 to 2009 are summarized below. |
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| Nestbox
Availability and Utilization |
| The program has
increased from 56 boxes in 2000 to a high of 113 boxes in
2004 and presently supports 87 boxes. The graph below shows
the number of nestboxes available each year (dark blue line)
compared to the number of nestboxes utilized during each nesting
attempt. A box was considered utilized if at least one egg
was laid in the nest. The graph below includes all bird species
that claimed a nestbox, not just Tree Swallows. Year 2002
marked the first year that a bird species other than a Tree
Swallow attempted to nest. Two pairs of Western Bluebirds
(Sialia mexicana) and one pair of House Wrens (Troglodytes
aedon) occupied three boxes during the first nesting period.
In 2003, one pair of bluebirds successfully nested and fledged
3 young during the first nesting period. Two pairs of House
Wrens and one pair of Western Bluebirds occupied three boxes
during the first nesting period in 2008. One box supported
a pair of House Wrens during the first nesting period and
Tree Swallows during the second nesting period in 2009.
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| Nestbox
Availability and Utilization |
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| If
you are interested in helping out with this program at the
San Joaquin Wildlife Sanctuary, please contact Christine Tischer
at
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| To
learn more
about the Tree Swallow Nesting Project, visit http://www.treeswallows.org
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