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Hummingbirds 523

location found, species (when known), age (when determined), reason brought into captivity,
initial condition assessment, final disposition, and release location. There is often confusion
between reason for acquisition and initial condition. Reasons can include such things as appar-
ently abandoned (in hummingbirds, calling from nest or parent not seen for ∼12 hours), found on
ground, rescued from predator, or “kidnapped.” Condition includes such things as dehydration,
out of nest, cold, starving, etc. Every attempt should be made to keep these categories distinct.
A detailed medical record should be kept on each animal, with results of the initial examination
recorded and any updates added as they happen. When large numbers of diverse species are being
raised en masse with different caregivers, it is useful to have a “feeding instructions” sheet that
tells the next caregiver what to feed and any tips for food delivery. A chart for recording the actual
time of each feeding and how much was fed is invaluable.

­ Initial­Care­and Stabilization

As is true for all types of baby birds, the main goals of initial care are warmth, rehydration, and
feeding, in that order. Hummingbirds that are in pinfeathers (∼14 days of age), feathered, or perch-
ing and too old to display gaping behavior, are probably able to regulate their own temperature
and thus need only temporary warming until their behavior indicates that they are normother-
mic. Then they must be persuaded to drink an isotonic rehydrating solution before hypertonic
nutrition is offered. For the initial stages of rehydration, 5% dextrose will suffice and will provide
a tiny bit of nutrition. This isotonic fluid tastes acceptable to the bird (if a fluid does not taste good
to the bird, it will refuse to drink). Gavage for hummingbirds is possible, but it is highly undesir-
able, so persuasion is the best route. Once the bird passes some fluid droppings, feedings can
commence.
For hummingbirds that are naked or in early pinfeathers, adequate heat is extremely important.
Newly hatched hummingbirds can weigh as little as 250 mg, so heat loss is rapid. Also, because of
the birds’ tiny size, hot and cool spots in incubators dictate how much heat they are actually receiv-
ing. Measuring heat with an indoor–outdoor wire probe‐style thermometer (available at many
home and garden stores) in the nest and under the birds is an effective way of monitoring the birds’
temperatures. Placing nestlings in a natural nest in an incubator at 100 °F (37.7 °C) and covering
with a small piece of flannel may provide adequate heat for all but the tiniest of chicks. If a bird
heated to that temperature fails to gape, the heat can be increased to register as high as 104 °F on
the probe under the bird. At that temperature, the nestling usually kicks off the covering blanket.
Under all these conditions of high heat, it is important to also monitor humidity in the chamber. A
wide‐mouth jar containing water and a cotton wick should keep the air adequately moist. Warm
hydrating fluid can be introduced into the gaping bird with any tiny plastic catheter placed on the
end of a 1 ml syringe. The response of a healthy vigorous nestling will be to “climb” the catheter
with the pulsing pumping motion observable in parent‐fed birds. Depending on the size of the
bird, amounts of fluid from 0.05–0.5 ml can be given at each feeding. Observation of the crop, easily
visible around the neck, can aid in determining what volume to give (Figure 34.1). Though hum-
mingbirds manage their liquid food very well, it is better to underfill than overfill a tiny crop.
Because these birds are gaping and won’t taste the food, they can immediately be given a hydrating
solution containing electrolytes, such as lactated Ringer’s solution (LRS) or a mixture of LRS and
5% dextrose. When they look plump and start passing wet droppings, they can be fed insects and a
nutritious fluid diet.