URN:catalog:ICE:TRBL:6069

Observer: 
Bob Barnes
Observation Date: 
2012-04-19
Best Estimate for Number of Birds Observed: 
243
Minimum Estimate for Number of Birds Observed: 
243
Maximum Estimate for Number of Birds Observed: 
480
Type of Estimate: 
Visual and Untimed
Precision of Estimate: 
Precise Count
Minutes spent at observation site: 
45
Singing: 
Yes
Distance to Stored Grains: 
100 - 500 meters
Distance to Water: 
less than 10 meters

238 counted moving from one large Himalayan blackberry patch to an adjacent Himalayan blackberry patch. Almost all of the 238 counted were males. On the way out to the site 35 individuals (c. a 50/50 mix of females and males) were found foraging in the pasture between the Public Access Trail and the old Bloomfield Ranch headquarters. They were not present on the return trip form the main colony site. Going to and coming back from counting at the main colony site, 4 females and a single male were counted in a very small patch of Himalayan blackberry. This group was still present on the way back to the Public Access Trail. Just before and adjacent to the main colony site the pasture was being freshly flood irrigated and a flock of 58 mostly males was foraging there. This flock was not present when the main count took place suggesting they had already moved into the first large Himalayan blackberry patch. The main count started with those birds visible as they sat on top of the two large Himalayan blackberry patches where next to the map marker for this eBird location. There were 14 individuals counted on each patch. Then over several minutes numerous individuals flew from the southern most of the two patches to the northern most patch of the two patches. The 28 "sentinel" individuals on top of the two Himalayan blackberry patches formed the start of the count with the 210 other individuals moving in a one way stream from the southern patch a few feet across and pasture opening to the northern patch. Those 238 individuals plus the 5 individuals found both coming and going results in the total of 243 individuals which were almost all males.
DISCUSSION/SPECULATION: The noise level in each of the two large main colony site Himalayan blackberry patches remained the same both before, during, and after the movement of the 210 individuals from one patch to the other. All 210 individuals came from out of sight in the southern Himalayan blackberry patch and disappeared out of sight into the northern Himalayan patch leaving only the 28 "sentinel" individuals in sight - 14 on each Himalayan blackberry patch. Since virtually all individuals observed were males, this suggests the possibility that females were already on nests except for the few observed . Assuming an equal number of females, the colony size would be 200+ pairs. If there were males already in the northern patch before the large movement there from the southern patch the number of pairs could have been much higher. The possible range of pairs in my mind is 200-400 with 200 being conservative and observed (based on 200+ males being counted).
NOTE: The count was easy because all the birds were moving in the same direction throughout. There was not the constant coming and going of individuals associated with many colony sites. Colony size to be determined after nesting cycle completed.