I have been linking through http://www.hancockhouse.com/
as the other site has too many hits and goes down often.
from that site:
Sad News:
April 30, 2006
Eagles and conservation have been the joy and occasional sadness of my life.
This is a sad moment. It appears that the Hornby Island bald eagle eggs are
infertile. The first egg should have hatched April the 26 and the second egg
today. The first embryo, if it developed at all, is surely dead. The second
embryo, could still hatch but I cannot see the proper pipping of the egg
shell, where the chicks beak has broken through enabling it to draw in air,
the precursor to the final struggle for hatching. It does not look good for
this pair this year. In fact this is the second year of failure for this
nest territory.
Reasons for the Failure to Hatch:
We cannot be sure. Some educated guesses follow.
The adult eagles are possibly old:
1. This is the 19th year for known nesting results from this tree. It could
have been occupied for 50 or more years earlier. Was the same pair occupying
the nest all that time? We do not know. Eagles could live that long.
2. If the birds are very old it is possible that they have simply run out of
reproductive ability. Perhaps they simply can’t produce viable eggs any
longer.
3. Alternatively, it is possible with very old birds that they have
accumulated so many pesticides and heavy metals that their reproductive
track is no longer able to function properly. This is not at all out of the
question. I am told that orcas (killer whales) that now periodically die
along the British Columbia and Washington coasts are so polluted and their
bodies so loaded with poisons that it is illegal to tow their bodies out to
sea or have them hauled to land fills. They carcasses have to be burned. A
very sad statement on our polluted earth. Are these eagles, who also occupy
the top of the food chain and eat the same basic foods as orcas, also
contaminated. Very possibly. Maybe the reproductive success is going to be
restricted to younger eagles that have not had so long to accumulated the
poisons.
One or more of the adult eagles is young and inexperienced:
1. This is possible – but not liklely. Last year when the territory only
hatched one young which died at 6 days of age and the other egg did not
hatch, both adults were in full adult plumage – not even just newly matured
at 5 years as this would have been indicated by the dark streaking in their
white head or dark tail band. These birds appear to be fully mature both
last year and this year. Furthermore, this pair appear to e very experienced
in nest building that we got to witness in such marvelous detail, and in
fullfulling the incubating duties. They hardly left the eggs unattended more
than 12 to 40 seconds during any exchange that I witnessed. They are not
just good, and I assume experienced parents, but so compatible with each
other. I take this beautiful pair to be very experienced parents. So the
loss again this year of their eggs I also view as most likely due to loss of
fertility due to age or polution.
Other alternatives:
There are infinite options but none seem logical than my first option above.
The pair are very used to human disturbance, constantly perching near houses
and human activity with no noticeable alarm or concern. While I have
received lots of concerned calls and emails at the sounds of power movers,
cars, chain saws and dogs we have had an unprecedented opportunity to watch
the eagles in the cam and correlate their behavior with disturbances. The
noise of civilizations does not seem to phase them a bit.
I found one call from an irate and annoyed caller quite interesting. She
heard the disturbance of barking dogs and instantly called me. I was
actually calling Doug to question him about this. After many rings he
answered the phone and reported that he delayed coming in to the phone until
the herd of barking sea lions has passed by his porch. I hardly think
barking sea lions would be a disturbance to bald eagles – and indeed barking
dogs elicit no interest from the nesting birds either.
Survival:
Eagles like most creatures in the wild are constantly subjected to the test
of survival. Can they find food and make a living? Can they avoid being
killed and eaten. Can they avoid hurting and damaging themselves? If they
can’t keep their feathers in good condition they won’t be able to fly
efficiently and hunt effectively and they will die.
Almost half of the eagles that start nesting loose their eggs or young.
Surviving in the wild is not easy. Of those young that survive to fledging
only a small percentage are likely to survive the five years to maturity.
Once they have proven themselves as good hunters and they enter the breeding
population they can produce young for 15 to 25 or more years. Now pause for
a moment to contemplate how many eagle there would or could be it the adults
were successful lin raising one or two young every year for 20 years! That
could be that each pair produced 30 or 40 young – far more than necessary to
keep the population stable. And stable would mean producing a new eagle for
every one that died.
Therefore, with such a long live potential, their has to be a lot of nest
failures or early deaths otherwise the world would be full of eagles – and
no room for any other species. Not a balanced system.
So as much as I was very saddened to not see our beautiful pair of adult
bald eagles produce eagles this year it is not an unexpected happening that
they should fail. If, as I suspect, these are old eagles, they have already
produced many replacements for themselves and they have been great
contributors to the very successful and expanding eagle population that we
have been experiencing the past 50 years. It is not a good thought that they
have stopped reproducing because they have become sterile from pollution and
this is also not confirmed.
We will hope and expect that other eagles will be more successful and they
their young will be flying over our waters. If our adult pair is at the end
of its reproductive life we can anticipate younger birds moving into the
territory shortly and becoming the parents of the next generations.
David Hancock
Mary Croix Ludwick, Librarian K-5 Elementary
Owen Elementary, The Colony, Texas (near Dallas)
ludwickm@lisd.net (school address)
ludwick@swbell.net (home address)
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