Briefly: We have a total of forty gourds of five different types, randomly assorted over five separate gourd poles around campus.
A rocky start to our season as events unfold. From our early clutch of six eggs (in a crescent Natureline) only one young has hatched, the other five eggs all have that dry look of old eggs. A puzzle; sparrows are an obvious culprit, but all five unhatched eggs looked otherwise intact.
We have also recorded our first loss of a clutch, a clutch of five eggs in a Supergourd that was due to hatch any day. Two were found intact in the entrance tunnel at the entrance, the other three eggs were missing, a broken egg found in the grass about thirty feet from the colony. Again, a sparrow is a suspect, but this week too we have been inundated by subbie males.
On the topic of sparrows, none have been trapped over the last five days although the gourd trap was left set, neither have any been seen pestering the gourds expect for one suspect male sighted intermittently on the pole with the lost clutch.
Thus far five broods have hatched, but only fourteen young were counted. There may have been an undercount of these still-tiny young in the case of two Carrol gourds and those five failed eggs in that one Natureline are skewing the results, but the largest brood seen so far is four young, a reflection of what seems to be a lot of smaller clutches this year.
Our average clutch looks to be about 4.6 eggs/clutch. Given normal rates of attrition that translates to an average fledge rate of less than four fledges/nest.
Last evening?s nest check showed?
8 crescent Big Bos: 8 gourds with eggs.
8 round-hole Carrols: 2 gourds with young, 4 nests with eggs, 1 nest, 1 nest start showing no activity since last week.
8 crescent Naturelines: 2 gourds with young, 3 gourds with eggs, 2 nests completed or under construction, 1 nest starts showing no activity since last week.
8 crescent Naturelines w/cling rod: 1 nest with young, 6 gourds with eggs, 1 nest completed.
8 WDC mod. exc. Supergourds: 6 gourds with eggs, 1 clutch lost, 1 nest completed.
On the bright side, the previous nest check showed eight gourds with no apparent activity, that number has now shrunk to four: one Carrol, and three crescent Naturelines. All with with nest material but with little or none added since last week.
Mike Scully
Purple Martin Forum
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