What you are describing isn't that uncommon at this time of year. Wind and rain can often flatten parts of hayfields, especially where the grass is very dense. In general though, we only seem to have large-scale abandonment when there is standing water on the fields and nests are flooded. We are into peak fledging season for Bobolinks, so there should be young that are out of the nest at this time. But, generally it takes a week or so post-fledging before the adults and young move very far from their nests.
We are past the point of time when Bobolinks will renest, so large-scale nest failure could result in birds leaving the field, aligning with what you observed. However, I would agree that the weather on the 29th would have been sufficiently severe to cause nest failure. But, I do wonder about the storms on the 26th which were pretty intense.
From: Vermont Birds [mailto:[log in to unmask]] On Behalf Of Carl Runge
Sent: Monday, July 1, 2019 11:28 AM
To: [log in to unmask]
Subject: [VTBIRD] Boblink weather event?
This morning Bruce MacPhersonand I went out for our weekly monitoring of Bobolinks at the Catamount Community Forest. This year with the property now in Townownership, we have been managing for grassland birds on an historical Bobolinknesting field. For the past 5years this field has been mowed with no successful Bobolink nesting. This year there has been no earlymowing and we were off to a good start. Last week on this 8 acre field, we counted 17 Bobolinks, male andfemale, with both sexes carrying food. Today was a different story. We first noticed that there was noBobolink song. On the central partof the field, the highest andwidest part where most of the Bobolinks were concentrated last week, there wasnot one to be seen. On thesouthern part of the field at a lower level, we found one pair. Both the male and the female wereagitated, with constant chipping and tail bobbing. The female was carryingfood. Nearby we saw an additionalfemale. That was it.
We noticed that the fieldappeared different, particularly the highest and widest central section. Thegrass was flattened in wide swaths. This did not appear to be from people ordeer walking through, but looked more like a wind event. On the evening of June 29 there was aweather advisory in the area and a storm passed through in the evening. This was short and did not appear to beoverly severe at my house about one mile from Catamount.
I am wondering if any of youhave observed anything similar or have any ideas about this. It seems ironicfor birds that fly so far to nest, to by stymied by a single event likethis. Or was it somethingelse? We will continue ourmonitoring to see if there is any recovery from this.