By Beth Sullivan
Those of you who have been reading
this blog for a while have by now realized I am quite fond of
(addicted to maybe) my little colony of Purple Martins at the Knox
Preserve. In all fairness, they are not “mine” but shared with
all who enjoy the Knox Preserve and are a direct result of two
Audubon IBA ( Important Bird Area) grants we have received.
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Adult male(L) and female wearing bands from last year. |
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Knox fields, great for insects, great for Martins. |
A Flying Snackbar
In the last two years we have
managed the habitat at Knox so that the fields are lush with a
variety of grasses and flowers that attract all sorts of insects. The
aerial insects are what attract the Martins, as they only catch their
food while flying. While it is a myth that Purple Martins are great
consumers of mosquitoes, they eat all manner of flies, grasshoppers,
flying ants, dragonflies and butterflies too. I guess we have to
accept they eat some that we actually enjoy ourselves. While doing
some research, I discovered that there are literally tons of
insect/invertebrates that are caught up in the air column-even those
that are not supposed to be in the air! Martins have been seen
bringing non-winged ants and other non-flying insects into their
nests. It is known that they do not hunt on the ground at all, even
when nearly starving!
Since the end of April this year I
have been monitoring the two sets of hanging gourd nests. These are
equipped with crescent shaped entrance holes that deter starlings.
They also have little “porches” on the outside, and in the new
set on the inside also, to aid the adults in landing at the entrance
and feeding the young. The birds seemed to like the new set better
this year, as we had more nests in the newer ones than the set we
erected last year.
Over the last months we watched the
birds as they constructed nests, by lowering the sets to peek inside.
Martins will use a variety of materials depending on what is
available. We start them out with clean dry pine needles; they add
small sticks and grasses. Several had seaweed/eelgrass, and they
often use mud. Once we saw them arranging green leaves, we knew egg
laying was near.
We used a diagnostic tool to compare
when the first eggs were laid and anticipated when hatching would
begin. An average clutch was 5 eggs. The first nestlings hatched
around June 19, and continued through June 27, each nest being
different. Most often all eggs in a nest hatch at the same time, but
developmentally there are some real differences as they grow.
On Wednesday July 9 a team from the
DEEP came out to band our birds. Avalonia volunteers joined DEEP
volunteers and we met first at Pequot Golf Course on Wheeler Road.
They have a very successful and mature colony and have produced over
90 young in 24 nests over the last years. Our nests produced 33
healthy young, and we added another 28 to our tally by including a
neighbor’s Martin house occupants! That is considered a huge
success for a new colony.
Banded for Identification
It is an amazing opportunity to
participate. Each nest is identified with a number. The birds are
removed from each nest into marked containers. It is essential that
they are returned to their exact nest once banded. Each bird is
fitted with a metal federal band with a unique number that will
identify it for life. They are then given color bands on the other
leg. Our colony has green/orange or green /yellow added this year.
With binoculars the colors can be seen and the bird can be identified
as from a particular colony. Pequot Golf Course has had blue/orange
since last year, and this year I discovered one sub-adult female bird
from Pequot had chosen to nest in our colony!
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Removing the young and noting the nest number. |
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DEEP and Avalonia volunteers staff the banding table. |
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This Martin sports new colored bands. |
The young are
weighed, and their ages are determined by looking at feather
development. Once all is recorded they are nestled back into their
gourds, and they settle right in. The parent birds are waiting
patiently, their beaks full of food for their hungry young.
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This one is about nine days old. The feathers are barely coming in. |
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This one is closer to 16 day old with much more feathering. |
The oldest hatchlings will fledge in
another week. Others following suit over time. They will remain in
the area, learning to catch their food and often return to roost in
their nest gourds for a while. All too soon they will gather and fly
south, well into South America, for the winter. We will await their
return eagerly next spring and look for their color bands.
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Adult Purple Martins return to their own nest, awaiting their young. |
We are very grateful for the DEEP
team, and all the volunteers that showed up at both sites. Many hands
made faster work, and we got a bit dirty, but the experience was
surely worth it.
Photographs by Beth Sullivan.