first birds will have arrived on the breeding grounds in the past
few days — the last week of April. They had been
delayed a few days because of snow and unfavourable winds. In the
next few days there will be a large influx of birds into the nesting
grounds and a flurry of nesting activity. With no known deaths over
the winter in Texas, the flock has 72 territorial pairs. In the last
four years we've had over 30
young produced each year. The high was 45 young in 2006.
How Many Young Will Hatch in 2008?
Things that affect the numbers of young that hatch
and survive are (1) predators and (2) weather conditions at time of
hatching until about 2-3 weeks after hatching. Cool, wet weather means
We're just coming to the end of a cycle of good production
of young, so this year (2008) may not be as good as last year.
In summer 2007,
84 young hatched, and 40 survived to flight stage and 39 of those
40 made it to the wintering grounds. I
expect we will have 60+ nests. We had 65 last year (2007), and 62
Conditions Affect Crane Nests and Chick Survival
expecting lower water conditions this year. The worst year for water
was 1981. May and August of that year had almost
no precipitation. Those very dry conditions
lead to some of the worst fires recorded in Wood Buffalo National
Park. That particular year almost one-third of the park burned.
It included a large portion of the crane nesting area. The dry habitat
resulted in only 3 young being produced; only 2 of them made it
to Texas. This was the worst production year on record.
that dry conditions are bad for chick survival. The family groups
have to forage over greater areas and likely outside their
nesting territory. Also, dry conditions make crane areas easier
for land predators, such as wolves and foxes, to reach the cranes.
Wet conditions are good
the cranes greater flexibility in choosing their nesting
sites. Wet conditions provide greater foraging opportunities for
the adults and chicks, and wet conditions restrict access by predators.
wet conditions are not necessarily good either.
Timing is Everything
Rain at hatching time and in the first couple of weeks after
hatching can be as deadly as drought. Under rain conditions the
become chilled and develop pneumonia. Food for
the chicks may be harder to find, which could also result in poor
will be starting aerial surveys to look for the nesting pairs beginning
around mid May. I hope that we will have as many nests as
last year. I'll be back with more news next week.