did some birds arrive in northern states earlier than ususal, even
with the wild weather?
Our weather and bird migration expert, David Aborn says that this
might be related to this spring's wind patterns. Good southerly
winds started in early March. Each bird has its own internal clock
(probably inherited) that tells it when it's time to head north.
The birds that, by nature, are the first to leave, got a head start.
They were then able to speed northward . . . between storms.
rubythroats were to arrive early year after year, climate change
could be part of the cause.)
We can predict when bad weather's coming, but hummingbirds
have no way to tell if it's ahead of them. When the conditions are
right for flying (for instance, no headwinds or heavy rain or snow),
hummers follow the instinct to head north to their breeding grounds!
Will rubythroats, and their food sources, survive
the cold and storms?
will, suggests our hummingbird expert, Lanny
"Freezing temperatures are not usually a direct factor in hummingbird
death. Healthy ruby-throated tolerate nights in the teens easily,
but freezing weather limits insect activity. In my opinion, the
spring migration is limited by the availability of active insects,
not by the blooming of flowers. Hummers can do without nectar, but
they need bugs at least every few days or their nutrition and tolerance
for cold suffers." (In the next section, you'll discover how
some early birds find insects.)
also reminds us that the migration starts with just a few individuals
in early March, builds over several weeks, then tapers off until
it's over by June. The map reflects the earliest birds in each location,
not the bulk of the population. Since they are spread out both geopraphically
and in time, the species is less vulnerable to severe weather.
a very small percentage of the ruby-throated population has been
caught up in this weather pattern. Will they survive? Lanny expects
most individuals to find enough shelter and food to manage, but
some will not. "There's an advantage to being first to arrive,"
he says: "A chance to claim the best breeding territories —
but there's always a risk of outrunning the food supply."
else helps rubythroats survive cold weather?
Sapsuckers: Flowers in cool northern areas may still be
weeks from blooming. With no nectar in sight, and few insects hatched,
how do the earliest birds get the energy they need? Some birds get
by with a little help from their friends! They feed on sweet tree
sap oozing from rows of small holes drilled into trees by yellow-bellied
sapsuckers. (These birds head north earlier than rubythroats do.)
The hummers also dine on insects stuck in the sap. Some people think
the northern limit of ruby-throated hummingbirds is determined by
the limit of sapsuckers. Just look at the pattern on these maps.
What do you think?
Sapsucker Breeding Range (red)
Hummingbird Breeding Range (red)
An Adaptation to Conserve Energy: At night — and
when the weather is too cold, windy, or wet, to find food —
a hummingbird can be at risk of starving. But each bird has a cool
adaptation to conserve energy. It can go into a sleep-like state
called torpor. A bird's body temperature can drop almost 50 degrees.
The heart rate and breathing slow way down. To come out of torpor
when it warms up, a hummer begins to vibrate its wings. This produces
heat. It can take an hour to come back to "life"!
can you do to help hummingbirds get by?
Don't wait to hang your feeders until after you see hummingbirds.
Let our maps guide your timing. The standard 1:4 feeder syrup won't
start to freeze unless nights drop below about 27 degrees Fahrenheit,
and even a slushy feeder is better than none at all. You can bring
your feeder inside at night if it gets too cold. You don't need
to worry about insects or shelter, because hummers are good at finding
both on their own.