It appears perhaps unfortunately that the nesting attempt at CSSP park has ceased, at least for the time being. However there is still presence by the pair and some interesting behavior.
- 05/17 a visit to the nest area didn't seem to have the female visible on the nest, although on many nests it can occasionally be hard to see an incubating female if she is flat on the nest and her angle doesn't allow her tail to be easily visible sticking out over the side.
- 05/19 At 09:15, the nest again did not appear occupied, but after a short time near the nest area some kik calls were audible by the SY male. He was spotted in a tree fairly close to the nest.
Over the next 10-15min, the male did show behaviors of flying occasionally to different tree branches and pulling at them, attempting to break off, consistent with typical nest building behaviors.
One flight was observed possibly carrying a stick to a conifer on the opposite side of the big bowl/depression directly west of the nest tree (approx 30m away), where glimpses of what presumably was the female were visible without a clear view. However some vocalizations which were likely copulation were heard from the tree shortly afterwards.
05/20: At ~06:35, the nest again did not show any sign of occupation, but within 5-10min some kik calls from the SY male were audible from adjacent trees. Searching the trees did locate the SY female, with deplumed (appeared to be passerine) prey which she was consuming. Within seconds the SY male flew in from some nearby location and copulated with the female.
The male left after copulation, and the female eventually flew into a conifer on the near side of the large bowl (closer to the nest tree, within 10m). However any new nest structure was not clearly discernable in these trees.
05/23: At 07:00, nest empty, and only caught one kik vocalization and a brief flight of one of the SY birds flying down the large bowl in a southward direction.
05/24: 06:15, from passerine alarm calls, the SY male was located in the vicinity of the nest site, again engaged in stick breaking behaviors (moving periodically to different tree branches and twisting with beak),
After several attempts a very long branch was flown away in a southern direction to another small bowl filled with mainly deciduous, and a couple of coniferous trees, which is ~150-200m south and slightly east of the prior nest tree. Finding the SY male in these trees, there was a very small start of a nest construction in one deciduous tree, with the male bringing sticks to it.
So it appears that the initial nesting attempt (which certainly seemed to have the female in genuine full incubation for a noticeable period of time) was abandoned for unknown reason. Presumably abandonment occurred sometime around Apr 17, consistent with other reports from other park birders. Perhaps some reasons could be:
1) Human disturbance: under normal circumstances territories in the area have always seemed to be very tolerant of human activity, so just ordinary presence presumably would not cause this unless there was something especially different about this female's behavior. There have been some concerns expressed about potential drone activity nearby, as one drone operator was observed fairly close to the nest (although not flying directly near it), this was on 05/21, but it leaves open possibility there could have been other previous drone flying. Whether this would affect them to the point of abandonment is unknown.
2) Egg predation by nearby mammalian predators, there are quite a lot of squirrels in the trees immediately surrounding the nest tree, although a squirrel seems less likely to be able to predate eggs from a Coopers female (other than perhaps factoring in that the bird would be nature of being SY be relatively inexperienced). More likely a scenario would be raccoon, as these are definitely present in CSSP and are seen in the area near to the nest.
3) An inability of the SY male to provide food deliveries serious enough to cause nest abandonment. There doesn't seem to be any significant indication of this though, and the fact that food deliveries certainly seem to be continuing from the male post-abandonment certainly suggest his hunting is at least adequate. The biggest hunting burden that might be difficult for the SY male would presumably occur after hatching as opposed to before.
It also seems clear that the nesting abandonment has not resulted in departure from the territory, and the pair have gone back to a number of courtship behaviors, it remains to be seen if there is a full nest construction or not. I don't know if they would actually progress again all the way to egg laying (other pairs in the general geographical area would be getting close to hatching in the next week or so, so they would be several weeks late). If they did so, would they be able to successfully rear young hatched a full month later than the normal window, also being SY birds, is also unclear.