In my previous post (Friday April 3rd) I recorded that SBC had come to Denis to do a film and radio shows on the Flycatcher introduction project. During their visit they were able to film two nests with birds incubating eggs and whilst I was with them I took the opportunity to take some photos and make some observations. We can not venture close to the nest so I was at the maximum zoom and digital enhancement the camera could offer. This coupled with heavy shade in this area means my photos are not the best they are sufficient however to highlight the observations.
Nest Structure:
The two nests showed an interesting variation in design. The first was constructed on the fine end of a down-hanging branch of a young Takamaka tree and looked rather precarious, the nest secured in position by being interwoven with a couple of leaf stems. The second was in the fork of a young sapling-like “upshoot” from an otherwise fallen Indian almond tree; but it looked all together more solid, being secured to the three woody stems of the fork.
The nests were also notable for their adornment with white materials. One appeared to have small pieces of white cotton, presumably plucked direct from the wild plants that still grow on the island. The second, meanwhile, was clearly festooned with white feathers. Rachel Bristol advised me that the birds in the source colony on La Digue also typically decorate the exterior of their nests with white materials. The only reason I can think of for this (and this is pure speculation) is that it may serve to break up the outline of the nest in the dappled light that typically penetrates through canopy making it harder for potential predators to discern.
Incubation, Nest Guarding and Chick Feeding:
During the SBC filming on that Saturday evening and Sunday morning we observed the the females incubating and then the male guarding the nest from a nearby perch when the female left it periodically. On the Monday morning however I returned to the nests and noted in one that the male tended to the nest directly including sitting in it. As I watched I realised that the male was in fact bringing insects to the nest meaning that the egg must have hatched in the last 24 hours. Over the next 20-30 minutes I also observed the female bring insects confirming the hatching.
Whiskers on Flycatchers:
On examining my photos a few days later what struck me was the prominent “whiskers” displayed by both male and female birds. The Flycatcher feeds predominantly by “hawking” i.e. the taking of insects on the wing. This requires high precision and fine last-second adjustments as obviously the prey will attempt to avoid being taken if they possibly can. I can only imagine that the whiskers enable the final adjustments through tactile stimulation to catch prey when they are perhaps too close to be properly seen.
On examining my photos a few days later what struck me was the prominent “whiskers” displayed by both male and female birds. The Flycatcher feeds predominantly by “hawking” i.e. the taking of insects on the wing. This requires high precision and fine last-second adjustments as obviously the prey will attempt to avoid being taken if they possibly can. I can only imagine that the whiskers enable the final adjustments through tactile stimulation to catch prey when they are perhaps too close to be properly seen.
Click images to enlarge. i). Male at nest. ii). Female bringing insect to the nest. iii). Whiskers evident on the female and (iv). male.
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