Wednesday, April 21, 2010

A bluebird family

The eggs have started to hatch in the Museum's bird box.  This morning, the webcam showed first one, then two young hatchlings.  Mom reappeared shortly after I saw the two chicks, and now has just left.

Click on the image of the nest with eggs to see what's happening now!  Both parents will feed and care for the young, removing egg shells and fecal sacs.

Here's a developmental timeline from (All about Eastern Bluebirds) --  we'll have an interesting couple of weeks ahead before fledging!
  • Development: When they are first born, they look a bit like hairy shrimp. Both parents feed the young. Nestlings defecate right after being fed - parents often wait for this and then take out fecal sacs, dropping them 21- 110 yards from the nest (rarely eating them.) See day by day photos to help with determining age.

    • Day 1: dingy gray down, eyes closed. The babies heads look huge. Their wings are nubs, and legs are weak and spindly. Uncoordinated, raising head weakly and unsteadily, faint vocalizations.
    • Day 2: contour feathers start to develop. Soft gray down is now along the edges of wings, the head and spine. The skin beneath looks blue-black as feathers begin to develop beneath it.
    • Day 3: femoral tract feathers begin emerging.
    • Day 4: wings are dark.
    • Day 5: feathers appear in crural region. Eyes open day 5-6. While sleeping, head held limply in front or curled to side.
    • Day 7-8: able to maintain body temperature.
    • Day 8: secondary wing-coverts break out of sheaths.
    • Day 9: capital feathers, secondaries and retrices are out of sheaths; birds use bill to work all major feather tracts. Nestlings may show fear if handled, can crawl. Yawning first observed. May lay head on scapulars while sleeping.
    • Day 10-11: most capital-tract feathers emerge.
    • Day 11: Feather sheaths start to disintegrate (leaving a white dust behind) and wing feathers begin to emerge. Nestcams indicate nestlings start to stand up at this age. Nestlings start to preen, pulling at the sheaths of emerging feathers.They may flap wings, stretch and hop a little to strengthen muscles.
    • Day 12: almost completely feathered. except for mid-ventral region. Incomplete bill-wiping movements and head scratching first observed.
    • Day 13: Mid-ventral region is feathered. sleep with head on scapulars. Can tell sex by bright blue color of primaries and retrices, and white on retrices. Sleep in typical adult manner.
    • Day 14: no unfeathered areas visible. Wings are longer. Capable of weak, short-distance flight. Bird can right itself and make short shuffling movements backwards and forwards.
    • Day 15: completely feathered. Nestlings huddle together, preen, exercise, stand on edge of nest and look out of nest cavity.
    • Day 16: able to hop well by day 16. During final days in nest, nestlings flap wings vigorously.

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