How and why I became a passive bluebirder. Before I go even a word
further I want to state that passive house sparrow control is not for
areas that are heavily under the control of house sparrows, nor is it
for a bluebirder who needs immediate control of house sparrows.
This can be viewed as a long-term effort of control, including periods
of setback.
All the trails I have monitored have been in
Eastern Nebraska.
The first trails I monitored were on a rotational
basis with other new bluebirders at the local nature center.
Overall trail responsibility rested with an employee at the nature
center and several more experienced bluebirder volunteers. All
activities other than monitoring were done by the more experienced
bluebirder. The rest of us just monitored the trail for nesting
activity and recorded it. This is not only where I got my start
bluebirding but my start with birding in general. It really was my
wife’s idea and I went along with as a form of exercise. This
was about fifteen years ago. I did this for about two or three
years but I wanted more control of my own trail.
At about this time the local Audubon group was
looking for bluebird trail monitors. So I was able to get just
what I was looking for. I took over my first bluebird trail that I
had control of and assumed all the responsibility for at that
time. I already understood that at no time should I ever let a
house sparrow fledge and in all this time I never have. I also
understood that house wrens were a protected species and their nests
could not be messed with for legal reasons. I became aware of the
Minnesota Bluebird Recovery Program at this time and immediately joined
(Nebraska’s bluebird organization had yet to come in existence).
I purchased the latest copy of Dorene Scriven’s book “Bluebird
Trails – A Guide to Their Success” and read it cover to cover.
I immediately came to the conclusion that this lady knows bluebirds.
My first year on this trail was the best this
particular trail had ever done, but there were problems. House
sparrows were rampant and house wrens were worse. The person doing
the trail before me had no experience with cavity nesters and just
monitored the trail and reported the findings. She knew to remove
house sparrow nests but she monitored very irregularly. At
this time we both were monitoring the trail and she was supposed to be
showing me the ropes. It became clear to both of us what needed to
be done. She broke her leg and quit bluebirding. This trail
by the way is a walking trail, a very hard walking trail of about three
hours through some hills that some might consider impossible. Not
only that but the trail is actually composed of six pieces of private
property (pasture) none of which was mine. The grass was not mowed
most of the year so to say the least it was a workout.
The next year on this trail I began by replacing
nestboxes that were falling apart and leaking water. Actually
there seemed to be no difference in production and house sparrows and
house wrens continued to be a problem. The house wrens were
particularly troublesome and other than removing their dummy nests
nothing else seemed possible. It actually appeared that I would be
fledging more house wrens than bluebirds. House wrens became my
number one problem. Yes I was witnessing house sparrow aggression
but at much less rate than house wrens.
The following year I started moving the boxes out
from brushy areas and started experimenting with other nest box types
(up until this time all boxes were a modified NABS style). I had
heard that Steve Gilbertson had developed nestboxes that were house
sparrows resistant. Although house sparrows were not my main
problem I decided to give these a try. I only placed two of
these Gilbertson Boxes on my trail. What I found was that the
house sparrows would have nothing to with them and the house wrens didn’t
care which house I put up they would fill them all with sticks if the
boxes were placed in poor habitat.
What really impressed me with these
Gilbertson
boxes, besides the house sparrows not liking them was the fact that they
were so light and I could easily carry them and mounting posts (even
several of them) along my trail. So I started to replace more and
more of my modified NABS style boxes with
Gilbertson style. I
started noticing a trend that when a NABS, Peterson, or any other wood
style nestbox was available and a Gilbertson style nestbox were
available on a the same portion of a trail, that the house sparrows and
house wrens would select these first leaving the Gilbertson style of
nestbox for the bluebirds (I had no tree swallows on this trail – no
water). So I decided to keep some NABS nestboxes but to move
towards having predominately Gilbertson nestboxes on all portions of my
trail.
I found a decreasing problem with both of these
aggressors but particularly from house sparrows. In fact by the
last year I had this trail (1997) I had no house sparrow nests making it
to the egg laying stage, no house sparrow nest attempts in a Gilbertson
nestbox and a significant decrease in house wrens attacks.
Monitoring was continued through this period at weekly (or less)
intervals. I turned this trail over to a new bluebirder and to my
knowledge he continues with the same success.
I took on an old trail in 1998 in a public suburban
park that had seen several years of neglect and lack of
monitoring. The boxes were in terrible shape and along a fence
line. I loaded myself up with six
Gilbertson nestboxes and
sledgehammer. Again this trail is a walking trail not as hilly,
but is done in one or two parts. You can’t drive up to the
nestbox sites you must walk. It is about 1.5 miles long and takes
about an hour to an hour and a half to walk. The first year was
not as bad as I thought it might be but I only fledged 12 bluebirds from
11 boxes.
The second year was more removal and replacement
with Gilbertson nestboxes, with similar results. This year I have
expanded the trail to sixteen nest sites (17 nest boxes with one nest
site paired as I do have tree swallows). I have added one new
Peterson nestbox and still have four NABS nestboxes on the trail.
To date, I have not had one house sparrow nest
completed to the stage of eggs being laid; I have had no house sparrow
or house wren attacks. Both of these species are heavily in the
area again with house wrens being the predominant problem. The
house sparrows and the house wrens have been keeping mostly to the NABS
boxes with only Gilbertson box being used by house wrens and none being
used by house sparrows. Don’t get me wrong; I am not claiming
that Gilbertson nest boxes are house wren resistant, but I do think they
prefer a NABS style box over the
Gilbertson. In fact what I think
is really happening is the bluebirds are settling for the nest box that
is left. It also seems that after the first brood of bluebirds
have fledged the house wrens seem to take over everything. It
becomes more important on my trail than ever to maintain frequent
monitoring to keep house wrens from completely taking over the trail.
02/23/05
