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246 Hand-Rearing Birds

to the captive diet gradually but then fed twice per day for a longer period in order to get more calo-
ries into the bird than if it were fed only once.
Once they start the home run to fledging, they naturally lose body mass and become fussy to
feed. They will start refusing their whole fish and previously easy‐to‐feed chicks will become more
difficult. Reduce the amount fed and fast the chicks every few days. Smell their breath – it should
not have a powerful or rancid smell.

Expected Weight Gain

Healthy chicks should have a consistent weight gain. In the case of Wedge‐tailed Shearwaters, they
naturally hit their peak mass at around 80–87 days and then will gradually reduce weight until they
fledge at around 109 days of age (Pettit et al. 1984). It has been documented in other shearwater
species – such as Sooty Shearwaters (Puffinus griseus), Manx Shearwaters (Puffinus puffinus), and
Cory Shearwaters (Calonectris diomedea) – that chicks with greater mass at fledging have a better
survival rate (Sagar and Horning 1998; Mougin et al. 2000). Ensuring that the chicks are in the best
possible body condition with plenty of fat reserves will give them the best possible chance of sur-
vival post‐fledge (Figure 14.6).

Housing

SOS has tried several substrates for raising shearwaters, including towels, net‐bottom cages, and
sand. The substrate that has worked best and promoted the best feather and foot health is sand
based. The chicks like to create their own nest cups and the best substrate to allow them to do this
is sand. The sand should be clean and dry. When they are very young and still in the guard phase,
toweling and a heat pad or an incubator is acceptable. Once they are past the guard phase and are
able to thermoregulate appropriately, then they can be moved to a sand‐bottomed enclosure. SOS
uses concrete mixing bins filled with a couple of inches of sand. The chicks also get a “burrow”
made out of waste paper bins cut in half (Figure 14.5), but this can be made out of any readily
cleanable material. The chicks quickly adapt to their new homes.

700

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Weight (g) 400
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0
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Figure 14.6 Weight gains of five Wedge-tailed Shearwater chicks.