Saratoga Springs, New York

Bird Feeding

Birds' Energy Needs Vary Seasonally

Winter birds

by Kevin Cook


Little birds discovered the first energy crisis long, long ago, and they deal with it now the same way they always have:  by eating.  Food and metabolism explain much of what you see birds doing.

Typical backyard songbirds are small and have high metabolic rates, of "high metabolism."


This metabolism thing is not easy to wrap your mind around because it involves a complex set of chemical reactions that take place in each individual cell of the body, with a resulting collective effect.  However, metabolism can be conveniently summarized in terms of energy consumption.

ENERGY


Think of your electric household appliances.  The clock runs on a 1.5-volt battery.  The smoke-detector uses a 9-volt battery.  The television needs 120 volts.  The clothes dryer takes 220 volts.

Use determines the amount of electricity consumed; each appliance has its own "metabolism," so to speak.  As do birds.

VARIED NEEDS

Working from the principle that a bird needs less energy to rest than to fly helps us understand that birds govern their feeding behavior according to whatever else they are doing.  Specifically, birds adjust both what and how much they eat.

  • Kind of food.  Birds such as tanagers, grosbeaks, and orioles spend late spring and early summer foraging mostly for flies, crickets, and caterpillars.  By late summer those same birds shift to fruits, focusing more on berries, pomes (such as apples), and drupes (such as cherries).  This is a prime time to put out oriole feeders in which you can offer fruits or nectar.
  • Amount of food.  During summer, many birds eat in bouts, with active feeding in early morning and late afternoon interspersed with casual feeding during midday.  Overwintering birds feed almost nonstop during daylight hours, and this is one of the most enjoyable bird-feeding seasons for humans.  The birds are hungry, and the extra food we offer helps them get through the cold weather.

OTHER FACTORS

Molting, nest-building, egg-laying, territorial defense, and migration all boost a bird's energy needs.  This elevated metabolism stimulates more active feeding.

The foods a bird chooses are also linked to seasonal availability and to growth stage.  Wild fruits are generally more available in August than in May; a growing nestling needs more energy than does a grown adult.

Even a vague understanding of metabolism brings new perspective to watching birds flit around the backyard.