Basic Math & Logic

[PM Pataskala]

Question #1: Which is greater - the number of Martins or the number of man-made cavities?

If the answer to the above is martins (which I suspect is the correct answer) then : Question #2:

Where do the "unhoused" birds nest and why do cavities go unused (that eventually are used)?

I have nothing better to do while sitting here waiting for my first bird than to think of these dumb questions, although I don't think this one is really dumb!

[pmlover]

mr pataskala it took me 15 years before i got them and i did have any idea what they were
I had been getting tree sparrows all the other years thinking they were purple martins>
where ar eyour houses located? in a field ? by water? any trees there?
thes all affect it if i can help you in any way i will, im in new concord

[Scully]

Question #1: Which is greater - the number of Martins or the number of man-made cavities?

Durn it, won't have my Cornell Lab of Ornithology "Birds of North America" subscriber site access back until next week ( http://bna.birds.cornell.edu/bna/ )

This is a great site that summarizes the current state of knowledge of every species in North America, each species account being written by the experts on that particular species.

But, working from memory, in the North Texas (IIRC) study area at least, it was believed that available cavities was the limiting factor. As in, in that particular population, martins appeared to outnumber available nest cavities.

In my area there are still many martin houses, almost all neglected, a little more than half of which are occuppied by martins in any given year.

Even in a typical 12 room house, only three or four cavities usually holds martins.

Reasons for low occupancy rate IMHO....

1) The tendency of martins to want to nest with other martins. Remember that martins abandon a site if they lose their eggs or young. That being so, a site that has martins most likely successfully fledged young the previous year whereas an empty site may be a dangerous site.

2) Starlings, and sparrows. Undoubtedly a major factor, not always an absolute barrier though. Almost all occupied sites in my area also host sparrows. One neglected house in particular on my street that has housed up to five pairs of martins in previous years held a pair of aggressive starlings earlier in the season and some sparrows.

Martins returned in February on schedule but did not stay. Now however two pairs of martins appear to be in residence and the starlings appear to have left.

3) Predators. Another old house I looked at still has martins, but this one I can lower, and it would seem of five nests, all but one has been destroyed, possibly by a squirrel. Two other old houses I know of are vacant because of squirrels. So much so I have found chewed pecan nuts on the porches.

There is also a prosperous area of town that had several active martin colonies at one time before an abrupt decline. Every one of these aluminum Trio houses has seriously bent railings. I believe the local barred owls or possibly a raccoon eventually learned there was prey in those houses.

4) Poor location of many housing sites. Again in my area, we have some active sites that boggle the mind that martins would use them at all. In one case the house is just six feet off of the ground adjacent to a sidewalk, so low that even sparrows wont use it. But it has martins every year. Other active sites are located under trees.

No question though that location is a major factor, even down here.

JMHO,
Mike Scully

[DebA]

Dick Robinson,
I love your DUMB questions! Unfortunately I don't have any SMART answers. I wonder if they spend a whole season trying to find housing or roost in trees? Poor things.