Extreme southeast corner, Grandview Cemetery, west terminus of Mountain Avenue, Fort Collins, Larimer County, CO:
The White-winged Crossbills continue their visit (Day 134) and nesting attempt. On warm days, both parents are gone from the nest quite a bit. Leaving the nest unattended is not without consequences. Today, several folks viewing the nest observed the nest being robbed of significant amounts of nest material by both Pine Siskins and at least one female House Finch. Both species are nesting in spruce trees very near the crossbill nest tree. If I had to guess at the function of the material being looted both before and after the robbery, it appeared to be "throw rugs and pillows", not "drywall or 2x4's". The finches taking the material were getting it from both the bottom of the cup (as accessed from below the nest) and the rim of the cup (at times the siskins appear to be in the cup). When the intruders engage in pilferage, the baby crossbills (we're still not sure if there are two or three) mistake their intentions as benevolent, and start begging for food. Does this mean the young are still blind, not picky who they bum a meal from, or both? As has been noted, the male crossbill does not like siskins and male house finches and often chases them away from the nest. I have assumed this was some sort of "grudge" from food competition episodes, or just instinctive chasing of any related species near the nest. Perhaps, in truth, it has something to do with recognition of their potential for nest material thievery. Also of interest today, both crossbills were seen eating both American Hackberry flower buds and American Elm flowers. I stayed at the nest until just after activity terminated at 7pm. The female's final behaviors were: she came into the nest from somewhere to the north, appeared to eat a fecal sac (although maybe this was a seed bolus coming out of her mouth), settled onto the nest, rearranged liner material along the nest cup's upper rim, closed her eyes, appeared to bring up a few seeds from her crop, and then just got motionless. Fledging is anticipated for a little over a week from today. The closer this event gets, the tougher the process becomes: perhaps there will be more nest material theft by other finch species; the food needs of the young will increase daily; maintenance of the nest will require more effort (both sanitation and wear-and-tear); squirrel threats will likely increase as the young crossbills become more vocal; crowding will occur; and available moisture very near the nest tree, at least in the form of snow, will likely disappear completely. The golf course is starting to water greens and tees. Maybe puddles will be available from this. Sheldon Lake, about 0.3 miles to the southeast, could always be their fallback option for water. Birders both yesterday and today reported seeing a Peregrine Falcon in the cemetery. The Turkey Vulture roost on Mountain Avenue about a mile east of the cemetery nw of the intersection of Washington is back in full swing. Still no young visible at the Great Horned Owl nest in the center of the cemetery. Dave Leatherman Fort Collins -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/cobirds?hl=en?hl=en To unsubscribe, reply using "remove me" as the subject.
