baby birds inside eggs need to hear their parents calling
- This article, just sent to me byTrudy Jensen, gives evidence for the
hypothesis that baby birds need to know that their parents are there
before they will peck their way out of their eggs. They know that by
hearing their parents calling to them. In the case of bald eaglets it
is a 30-hour process. These eaglet eggs were in incubators and a
recording of calling parents was played to them. The technique was
Monday, April 25, 2005
By CAROL BENFELL
THE PRESS DEMOCRAT
Three baby bald eagles now nestling under their mothers' wings at San
Francisco Zoo bear the unlikely names of Sister Sparkle Plenty, Sister
Barbi Mitzvah and Sister Carmelita Cheesecake.
The eaglets were named for members of the Russian River Sisters of
Perpetual Indulgence, a group of men and women who dress in outrageous
female costumes to raise money for charitable causes.
The Sisters donated $350 for a first-of-its-kind sound system that
enhances eaglet survival by piping the cries of parent eagles to eggs
in incubators at the zoo's captive-breeding program, which raises
eaglets and releases them to the wild.
Their modest donation provided what the zoo's faltering budget could
not: It allowed animal keepers to test a technique that has worked well
with other bird species, but had never been tried with bald eagles. The
zoo is now poised to send copies of its eagle CD to other
"I'm very happy about it," said animal keeper Kathy Hobson, who manages
the zoo's bald eagle program. "It's definitely making it better for the
chicks. I haven't lost anyone in the process of hatching this year."
The Sisters seem almost as happy as Hobson and have put a video and
pictures of the tiny, fluffy, big-footed eaglets on their Web site.
"You look at this little piece of life that's been given a chance and
it feels great," said a Freestone resident who would identify himself
only as Sister Sparkle Plenty. "We feel like we're making a
San Francisco Zoo, with seven pairs of bald eagles, houses the nation's
largest captive bald eagle breeding program. The program began in 1985
to halt the decline of wild bald eagles, whose young could not survive
in DDT-weakened eggshells.
The state bald eagle population had plummeted to 30 breeding pairs by
the late 1970s, down from the estimated historic level of 400 breeding
pairs. The birds are recovering and now number nearly 200 breeding
pairs, according to the state Department of Fish and Game. The are
federally protected as a threatened species.
San Francisco's bald eagles are housed in the Avian Conservation
Center, where Hobson and volunteers remove the eggs from the parental
nests as soon as they are laid.
The eggs are placed in incubators, where the heartbeat of the
developing embryos is continuously monitored and temperature and
humidity are held constant. Volunteers turn the eggs several times
The aim is a higher rate of hatching than would occur naturally in the
parental nest. "In the eagle's nest, it's very hard to know and help if
something is not going OK," Hobson said.
But last year, the first year the zoo had used an incubator instead of
mother hens, many of the chicks didn't hatch. Hobson and the volunteers
worried, but weren't sure what had happened.
"You'd open the shell and there were these perfectly formed babies,"
said volunteer Susan Magrino, president of a Burlingame software
company. "I wondered why they didn't have the oomph to come out of the
The answer came to Magrino in what she calls "a magical moment" as she
watched Hobson whistle to an egg and heard the egg chirp back. The
hatching eaglets wanted to hear their mother's voice.
"If you were a baby eagle and you heard your mother, you'd want to come
out of the shell," Magrino said. "Why would you come out if there's no
one there to feed you?"
Hobson worked on the incubator, and Magrino - on the advice of a Monte
Rio friend - applied for a grant from the Sisters of Perpetual
Last year, Magrino's vice president, Priscilla Joyce, and her husband,
Jerry Joyce, recorded the chirps of babies and the raucous screams of
the adults at an eagle's nest at the zoo.
Earlier this year, as nesting time rolled around, Jerry Joyce wired the
incubators so a CD of the nesting eagles could be played directly to
The technique has worked well with other species but apparently has
never been used with bald eagles, Hobson said.
The results were immediate.
Eaglets still in their shells began chirping in response to the
recorded parental cries. Twelve eaglets pecked and slept and pecked and
slept until they made it out of the shell - typically a 30-hour
process, Hobson said. Three more eggs are expected to hatch next week.
One of the babies was named "Little Jerry" in recognition of Joyce's
"You can see the difference," Hobson said. "They're alert, they're
calm, they know their parents are there. They know they're not going
out into nothing."
Hobson said she'll be sharing the eagles' CD with other bald eagle
breeding programs around the country. "If I'd had this last year when
my chicks were dying, we might have saved more of them," she said.
The Sisters have started a trust fund for the eaglets on their Web
site, www.rrsisters.org, and are considering a special fund-raiser for
the breeding program in the coming year.
"We realized it was a wonderful opportunity to do something for our
environment and a vanishing species," Plenty said.
The 12 members of the Sisters of Perpetual Indulgence raised $70,000
last year and donated it to 52 charities. Working as volunteers at
other charitable events, they helped raise an additional $212,000,
- Well, it seems there's only one hawklet, not two. Probably the adult
"clean-up" behavior that I thought indicated a second hatching was
continuing clean-up after the first hatching.
After the hatching day (Wednesday, April 27) I had to leave home for
four days. I came home late Sunday. On Monday morning (May 2) I raced
out to see what was happening. My vantage point is about 50 feet from
the nest, on the ground, looking slightly up. One adult was sitting
pretty high in the nest, looking down into the nest every once in a
while. Then it began tearing at some food and obviously feeding it to
young I couldn't see.
I ran to my ladder and climbed onto the roof of my yurt, which is flat,
from which I have a level view of the nest. The roof-top is twice as
far away as the ground-based viewing point, but it affords a better
view into the nest. There I saw one hawklet eagerly devouring raw red
meat as fast as the parent could supply it. Its head was a very fuzzy
off-white. The adult was indefatigable in supplying food, delicately
tipping her head to the side with each offering, which apparently made
it easier for the hawklet to take the meat from her. The feeding
continued at an unrelenting pace for perhaps 8 minutes, at which point
the baby lost interest.
The adult swallowed a few morsels herself, and then tried to interest
the baby in more. She would hold a piece in her mouth, tip her head to
the side and proffer it to the hawklet. When it was ignored she would
tip her head the other way, nudge the young one with it, and finally
swallow the meat herself. After looking around a bit she'd tear off
another piece, and again offer it the uninterested youngling. This
process lasted for several minutes, with the hawklet occasionally
accepting a piece, but mostly ignoring it's parent. Finally the parent
Later that day I was able to see just a little of the baby's head from
the lower viewing point, and watched as an adult flew in carrying a
rodent. Both adults stood on the edge of the nest while one ate. So far
these birds mainly seem to be catching mouse-sized rodents. I don't
know my rodents well enough to be sure exactly what they are bringing
in, but yesterday I might have seen a small gopher. The tail was short.
Once I saw an adult flying about 40 feet from the nest with a bird
clutched in its talons but the bird must have gotten away, because
shortly afterward both adults were at the nest with no bird. [It says
in the Birder's Handbook that Red-shouldered Hawks eat small mammals,
birds, and snakes, but I suspect they actually don't take many birds
(anyone?). I learned from Alida Morzenti (raptor expert par excellence)
that there is a correlation between sexual dimorphism and mobility of
prey: the more mobile the prey, the greater the sexual dimorphism.
Birds are the most mobile prey, of course, and because the RSHA female
doesn't appear to be significantly larger than the male, that would
indicate that these birds don't prey on birds very much. I can't find
my notes, but I think Alida taught us that sharp-shinned hawks have the
greatest size difference. The male is so little he can't incubate the
eggs because he can't cover them. There's more to this theory - e.g.
why that correlation - but that's too much to go into here).
On Monday I also saw an adult pick up a sprig of oak leaves and drag it
to the edge of the nest.
Yesterday (Tuesday) the baby was so much bigger (or perhaps stronger)
that its entire head was popping up over the edge of the nest and was
visible from the spot on the ground. My friend Larry and I held our
business meeting at the viewing spot so we wouldn't miss anything. We
again observed diligent provision of prey and feeding of baby. At one
point after the baby was finished feeding the adult walked over to the
right side of the nest and dragged a sprig of half dead oak leaves into
the nest. It pushed and tucked until it was in just the right spot, and
then flew away, leaving the hawklet alone in the nest. We speculated
that perhaps the sprig was intended to hide the baby, and/or act as a
physical barrier to predation. But it was put on the other side of the
nest from where the baby was, so wouldn't have been very effective.
The adults frequently leave the baby alone fairly frequently, but for
very short periods - less than a minute, I'd say. They do this perhaps
as often as every hour. I'm not sure why - perhaps to relieve
themselves away from the nest. That bear investigation.
I've gotten no response about a webcam. Would it need to be sheltered
from rain? If so, I could provide a shelter quite easily.
Peregrine Audubon Society
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- On Saturday, after the Peregrine field trip, I asked Roger to show me
the Blue Gray Gnatcatcher nest he had found in Low Gap Park. We went up
there, and when he found it he was shocked to find it in a shambles.
But as we tried to figure out what had happened, a gnatcatcher flew to
it, then left rapidly. That happened again. We speculated that the bird
was removing nest material.
So Roger kept watching the disheveled nest while I ventured forth to
find out where the birds were taking the nest material. While watching
the gnatcatchers zipping around I got distracted by a couple of Anna's
Hummingbirds. As I watched one of them landed, and close inspection
revealed that she had landed on a nest (the first one I've found!).
Shortly after that Roger and I simultaneously found the new gnatcatcher
nest nestled in the crotch formed by two or three branches about 12
feet up in a small blue? oak (the abandoned one was in a similar spot).
I think there are no eggs yet.. The male and female were taking turns
flying in and doing "settling-in shivers" - wriggling and rapidly
shaking their bodies as if to try the nest out for size and see if they
were comfortable or if they needed to make improvements.
Roger set up his digiscope equipment and took both still and moving
We walked further up and found other gnatcatchers zipping around and
speculated that there must be another nest in the vicinity. There were
also house wrens clearly nesting somewhere near.
The red-shouldered hawklet is growing by flights and bounds. Now I can
see to the middle of its breast from the lower vantage point, and it is
spreading its wings occasionally. Today some friends and I watched for
about an hour while it was raining (we were safely under a large picnic
umbrella) and never saw an adult bring food, nor did we see the baby.
That was the longest interval with no feeding and no sight of the baby
yet. I speculate that it's harder to catch rodents when it's raining,
and that the adult wasn't getting up and changing position because she
was trying to keep the baby dry and warm.
We left, and when I came back 30 minutes later the adult was almost
finished with a feeding. When s/he finished s/he flew off and came back
within a couple of minutes. I have now seen intervals of 2 minutes with
no adult at the nest.
Peregrine Audubon Society
- I will be holding an Open Nest on Saturday, May 14, from 9 a.m to noon.
Anyone interested in nest-watching should email me, and I will email
back directions. Scopes welcome. Digiscopes particularly welcome!
Who can tell me if raptor babies are fed whole, unregurgitated meat
from the moment of birth. I missed the first few days of this young
5/8,9 Rain. During the rain the feeding intervals may have been less
frequent (harder to hunt?). I think the baby was left alone less,
perhaps to prevent hypothermia. The adult on the nest seemed very
conscientious about keeping the baby warm and as dry as possible. I
worried that the baby might not survive, as I saw a red shouldered hawk
nest fail two years ago, when we had eight inches of rain in April. But
maybe that was an incubation failure. I couldn't see that nest well
enough to know what was going on.
5/10 (a.m.) Sunny day. Saw a parent bring a lizard to the nest. I now
hear peeping when a parent arrives, even without food. Baby appears
vigorous and has a good appetite. It's funny to see a sharply aquiline
profile on such a fuzzy head and body. The bird overall appears to be
about the size and shape of a small crookneck squash.
The baby was left alone in nest for almost 3 minutes. That's the
longest yet. During that time the baby was quite active, spreading its
wings, looking around. It gazed straight at me for a while. The upper
mandible is starting to turn yellowish - a light yellowish-green.
Overall the baby is still grey-white, but I might be seeing a little
bit of reddish fuzz appearing.
(p.m.) Watched with Kayla. An adult brought in a large
rodent, and transferred it to the sitting bird. Sitting bird became
standing bird and fed her/himself, and the baby. Saw long-worm-like
bits of meat. Intestines? Kayla and I both thought we saw something
white fly out of the nest. Projectile pooping? Or was it a moth flying
by? Baby left alone in nest for a couple of minutes. Was it trying to
tear food on its own? Don't think so, but maybe. I suppose the adults
will soon cut back on the tearing and proffering of food so the baby
will have to learn to feed itself.
This baby has to grow so much and learn so much in a mere 39-45 days.
When fledging time comes I hope I can watch around the clock.
5/11 (a.m.) Sunny day. Definitely saw something white ejected from
inside the nest, vicinity of baby. Must have been projectile pooping.
Quite a talent. Big rodent brought in. These parents are so competent!
Why have I never seen a red-shouldered hawk catch anything? I've never
even been aware that one was hunting. Mostly I see them sitting on
branches or flying around and calling. I'll have to watch longer.
To be continued..
Peregrine Audubon Society
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- These pictures (below) were taken by Jon Klein yesterday. He climbed an
oak to get closer to the nest, and has set up a blind with green sheets
and camo netting way out on a mossy horizontal limb. Pretty ingenious.
I have pictures of him climbing the tree, and pictures of the blind,
but on 35 mm. He came back today for more pictures, and is up in the
tree right now. The light is more diffuse today, so the shadows won't
be such a problem. He's hoping for some feeding pictures. I'm working
on my laptop at the landlubbers' viewing point, so I get to watch it
The absent adult is crying in the distance right now, so maybe it won't
be long. (Jon is a young professional wildlife photographer, so please
don't do anything commercial with these pictures and credit him if you
send them on or use them in any way. And if you'd like to see more of
his work, and/or buy something from him, please contact him at
jon3klein@... or 937-0067.
The hawklet is too big to fit under the mother today, so it is sitting
and clambering around beside her. Sometimes quite close to the edge.
Chastity, a Round Mountain denizen, I both started wondering about the
likelihood of it falling out today. I can't imagine how a second baby
would have fit in the nest. The baby is definitely chirping. I think
it's hungry right now. It appears to be about a third again larger than
it was yesterday!
Oh, here we go! A rodent was just dropped off. The adult is ignoring
it. Baby is cheeping away. Parent looks around as if wondering what all
the commotion's about. My guess is that she's hoping the baby will
start feeding itself....more waiting. Finally the parent gives in and
starts delicately proffering food. It's sunny again, so the light might
not be ideal for the pictures, but the birds are shifting positions
quite a bit during this feeding, so I bet Jon's getting some good
Now both adults are on the nest, with the baby between them, oriented
toward Jon. I hope he's getting some "proud parent" pictures. I laugh
out loud because they look so beautiful through my binoculars, and the
second adult flies off. Darn! Generally they seem pretty oblivious to
noise, but I'm pretty sure I startled him. Sorry Jon!
Jon came down and told me the male has the grayer head, is a little
smaller, and is definitely the one hunting. Or at least that was the
case today. It's good to have that question answered.
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- Hi All. This hawk diary business has become very time consuming!
Between watching and writing and orienting friends to the nest, and
entertaining friends who come to watch I'm finding it hard to get
anything else done! Eeek! But it's a labor of love and this opportunity
may never come again. Now my diaries are being printed in the Ukiah
Daily Journal, with Jon's incredible pictures, so I am working more on
the quality of the writing than I did on the installments I sent out
before. (You'll notice a little early repetition in this installment,
which is what I just sent to the Journal).
Unfortunately the Journal all of a sudden printed the first unedited
draft I had sent to them as a teaser at a point when I thought we were
still in the negotiation phase. So I've learned never to send anything
that I don't consider print-ready. But Richard, at the Journal, and I,
are developing a good working relationship.
Jon Klein has driven here from the coast three times now, and has spent
4.5 - 5.5 hours in the blind at a time. Again, please don't send his
photos on, or use them in any way without giving him credit. BTW, the
Journal is going to do a full story on him, with pix. Richard
interviewed him yesterday.
For those of you on Mendobirds, for some reasons the pictures don't
come through, but George Chaniot is posting them on the Peregrine
HAWK DIARIES (2ND INSTALLMENT FOR THE UKIAH DAILY JOURNAL)
Special to the Journal by Kate Marianchild
(This is the second installment of my diary about a red-shouldered hawk
family that lives near my home. I live in oak woodland northwest of
Ukiah. The nest is high in an oak tree, and is about 60 feet from my
viewpoint. The sex of the hawk baby is not known, but I have decided to
refer to her as a female in order to make the writing easier).
Sunday, May 8
Rain. The red-shouldered hawklet is growing by flights and bounds. She
spreads her grey-white wings and the breath catches in my throat. She�s
so young, and so new to her wings. One of the parents is keeping her
warm. I�ve learned that only half of bird babies survive until it�s
time to fledge, but I hope the numbers are a little higher among
raptors. I hope this baby will fly.
She survived the rain. She is 13 days old today.
Morning � A parent brought a lizard to the nest. I now hear peeping
when a parent arrives, even without food. The baby (my goddaughter!)
appears vigorous and has a good appetite. It's funny to see a sharply
aquiline profile on such a fuzzy head and body. Overall she appears to
be about the size and shape of a small crookneck squash.
The hawklet was left alone in nest for almost 3 minutes. She gazed
straight at me. The fleshy part at the top of her upper bill, the cere,
is starting to turn a light yellowish-green. Overall she is still
grey-white. She has about 30 more days to grow into her full size and
plumage before she fledges.
Late afternoon: Watched with Kayla. Kayla and I both thought we saw
something white fly out from the center of the nest. Projectile
Sunny. Definitely saw something white ejected from inside the nest,
vicinity of baby. Projectile poop. What a talent. Big rodent arrived.
These parents are so competent! Jon Klein came and took pictures today.
He climbed an oak to get closer to the nest, and set up a blind of
green sheets and camo netting. Inside the blind is a structure of
lashed 2x4�s that he sits and leans on. It�s way out on a mossy
horizontal limb 25 feet off the ground. Ingenious. He figured out that
the adult who spends the most time at the nest and feeds the baby is
definitely the female. The male is smaller and has a greyer head.
Jon came back today for more pictures, and is up in the tree right now.
He's hoping for feeding pictures. I'm working on my laptop at the
landlubbers' viewing point.
The hawklet is too big to fit under her mother today, so she is sitting
and clambering around beside her. She appears to be about a third again
larger than she was yesterday! What if she falls out?
I hope something interesting happens so Jon can get good pictures.
Oh, here we go! Dad arrives, huge wings spread for landing, carrying a
baby rabbit. Rabbit transferred to Mom, who puts it down. Dad leaves
the nest immediately. Baby chirp-chirps. Mom looks around as if
pretending she doesn�t know the rabbit is there. Is she hoping the baby
will start feeding herself? More waiting. Finally Mom gives in and
tears off a chunk. She tips her head and delicately offers a morsel to
her baby. The next bite is way too big for baby so she gulps it down
herself. Mom has an absent-minded moment and drops a chunk of flesh on
her baby�s head.
May 12, 2005
I heard a commotion and came out of my house. High overhead a
red-shouldered hawk was screaming at a circling red-tailed hawk. He
screamed and screamed until the red tail nonchalantly drifted out of
�our� territory. I ran over to the nest. The baby was alone but OK. Had
Mom participated in the defense of the baby?
The little hawk was not very active today. I am worried that she is
sick. I couldn�t help but think how helpless the parents would be if
faced with a sick youngster. At around 6:30 p.m. the mother kept
tucking and pushing a big sprig of oak leaves around in the nest. Maybe
she�s trying to raise the floor, which must be pretty gunky by now.
Baby has started scratching and preening. The tips of her wing feathers
are turning black. They look like black fringe. The intervals when no
adult is at the nest are getting longer - maybe 8-10 minutes.
I have a burning question: where does the dad spend the night?
May 14, 2005
The mom is working at arranging lichen (old man�s beard). Does it help
control mites and vermin? The baby falls over a couple of times while
trying to move around in the nest. I wonder if she has a bad leg. Both
parents are away for 50 minutes � the longest absence yet. I hope they
haven�t abandoned the baby because she�s gimpy. I�ve become a very
Mother comes back carrying a branch with trailing lichen. Puts it on
the floor of the nest. Oh, I get it! When the baby falls over it�s
probably because she�s tripping on branches and twigs and lichen.
It�s after noon and the baby hasn�t eaten since 9:30. Mama�s clearly
wondering when Dad is going to come with food. She finds a dried up old
carcass lying around in the nest and tugs hard to get a few ratty
strands off of it. Baby chirps. Receives a skimpy morsel. Mom flies off
with the old carcass clutched in one talon. She calls from nearby, but
gets no response from Dad. She flies back and lands on a branch near
the nest, still carrying the carcass. She keeps looking around and
calling for her mate. I wonder if something has happened to him. She
flies back to the nest, still clutching carcass. More than an hour
later, at 1:21, Dad finally arrives with a rodent. A foodless interval
of almost 4 hours.
Baby much bigger. Her wingspan might be 24 inches! She survived the
latest unseasonable torrential downpours. She�s preening a lot, and
walking more confidently on edge of nest. But she looks like hell -
like a wad of cotton that got rolled around in dirty sand. It�s because
her dark colors are coming in. Mama appears to be eating lichen.
Jon in tree. It looks like Mama is eating mites off the baby. How? Does
she spear them with the hook on her bill? Dark banding is showing on
baby�s tail. No sign of baby feeding herself yet.
Jon comes down. He says my goddaughter is spoiled! Years ago he watched
another red-shouldered hawklet, and by this age both parents were away
from the nest most of the time. They would just drop off food and leave
the baby to feed itself. Once he saw them drop off a live snake. The
baby tried to swallow it live. The baby would get the snake halfway
down and then it would wriggle back out! Gross. Jim Armstrong is
watching a red-shouldered hawk nest right now, and �his� baby is alone
most of the day. My goddaughter has her mom with her most of the time,
and is still being fed.
I�ve been pondering the� spoiled baby� question. I have four theories:
1) the baby is delicate in some way and needs extra care; 2) she is a
slow learner; 3) there isn�t a lot of canopy above this nest, and one
parent has to be there most of the time for protection; 4) the dad is
such a good provider and the hunting is so good that this family can
afford to have a Stay-at-Home Mom. I lean toward the latter theory.
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