8/27/12
The bones of the walk were about as good as you
could reasonably expect for a warm August day.
We came up with 19 species, just shy of our first
20 bird week since mid-June (week 25) and a
little bit less shy of the record 21 for week 35,
which was set back in 2002. Still we were well
above the median of 13 and we had two excellent
highlight birds.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
I decided to check on what it was that made the
2002 week 35 walk so strong and how that group
managed to pick up two extra birds versus our
walk. I had expected that the difference would
turn on our missing a couple of common birds (for
example, we didn't get a raven, which we might
have reasonably hoped for, and I know that scrub
jays were still common on campus in 2002).
However, if you look at the two bird lists, the
overlap is rather weak with only ten species
common to both. We had a Nuttall's woodpecker.
They had a downy. We got a turkey vulture. They
got the raven. They got a mockingbird and a
starling. Pooh! We saw lots of lesser
goldfinches. They saw a western bluebird. We
had a mountain chickadee. They got an orange
crowned warbler and a hermit warbler (!), a
seriously rare bird for Caltech but so
distinctive, I can't believe they could have
blown the id. We picked up two rare birds, which
are described below.
2002 keeps coming up when I come across rare for
Caltech birds and it still holds half a dozen of
the record bird walks for number of species seen
on an individual walk (it originally held 15
records with four ties). In terms of species,
2002 was easily the best Caltech bird walk year
up to that point with a sum total of 889 species
reported for the year (732 being the previous
best). My first supposition is that the winter
of 2001-2002 was extremely dry and that this led
to a lot of birds seeking new habitat in our lush
aqueduct fed lowlands, especially during autumn
dispersal. Dry years lead to low water and,
therefore, low food stocks whether you are after
seeds or insects. This is the word for Caltech
bird is water theory of abundance. The winter of
2006-7 was equally dry and 2007 had even more
total species (938) than in 2002, making it the
most species-rich year to that point. My dryness
theory then runs into water, however. The
winters of 2008-2011 were not excessively dry;
yet species totals for 2009, 2010, and 2011 all
exceed totals for 2002 and 2007. I view this as
partly a consequence of the Station fire of 2009,
which destroyed a lot of habitat (that just has
to be where all those mountain chickadees are
coming from) and partly due to an increasing
number of eyes on the bird walk. So, is it just
the lack of food and extra eyes and ears that
lead to more sightings? Perhaps Alan has some
thoughts on the matter.
The first highlight bird was brought to us by
Vicky. In Tournament Park, she is looking up
into the canopy and sees a flycatcher in action.
The visceral response is that we have another
black phoebe but the height in canopy is too high
for a normal black phoebe and, with a little
looking, it was obvious that we were dealing with
something in the Contopus flycatcher clan (wood
pewees and olive-sided flycatchers) and not a
phoebe or Empidonax flycatcher. The bird is in a
tree next to the track, so we have limited angles
to play with and the bird keeps picking what are
for us poorly exposed perches. However, we
eventually manage to work it reliably down to a
western wood pewee and Melanie has a new lifer.
This is only the eleventh western wood pewee
reported on the Caltech bird walk. These birds
winter in northern South America and breed all
the way from Guatemala and Honduras, north to
Alaska. And, if you plot up our sightings, it's
clear that we are sporadically catching the
pewees coming and going. In the Spring, we have
sightings from late April to late May with one
sighting on week 17, three on week 19, and one on
week 21 (this year). For the Fall migration, we
have had three sightings in week 34 and one each
in weeks 35 (this year), 37, and 38 (i.e., late
August through late September). We also have a
sighting from week 9 in 1999. I must admit to
finding that one a little suspicious but birds do
end up in odd places at odd times.
The themeing of a walk can be moment or a view or
it can found in a single chip. This time, we had
a classic Darren moment. We had left Tournament
Park and its pewee and passed the hummingbird
lady's house. We are walking along the driveway
towards Wilson Ave, when Darren hears a chip, not
a chirp, not a song, not an extended soliloquy to
the tasty glory of the California oak moth. We
have a single tentative chip and Darren
immediately calls a black-headed grosbeak. How
cool is that? It took several minutes for us to
get a viable view of the bird but, eventually, we
all get a decent look. It is a juvenile (or
perhaps adult female) with a yellowish buffy
breast, well defined wing bars, sharp eyebrow,
and a classic grosbeak beak. It was another life
bird for Melanie.
It was only the ninth sighting
of a black-headed grosbeak on the Caltech bird
walk and only the second dispersal sighting.
Most of our sightings are from the Spring weeks
17-20 (late April to mid-May), when the males are
flamboyant and, often, rather talkative. Both
the males and females move through our area over
a roughly two week period, hence a big spike in
week 17. In the Fall, the males leave first, in
late July or early August and we have one
sighting from week 31 that was probably one of
these birds. The adult females and juveniles
pass through, starting in late August, such as
our bird of this week, but we have a legitimate
shot at another up through the end of September.
Incidentally, we now have the record for
sightings of black-headed grosbeaks in a single
calendar year (all of two).
The date: 8/27/2012
The week number: 35
The walk number: 1158
The weather: 90°F, sunny
The walkers: Vicky Brennan, Darren Dowell, Melanie Channon, John Beckett
The birds (19):
Rock Pigeon
House Sparrow
Mourning Dove
Anna's Hummingbird
Acorn Woodpecker
Lesser Goldfinch
Mountain Chickadee
Yellow-chevroned Parakeet
Nuttall's Woodpecker
Red-shouldered Hawk
Bewick's Wren
Black Phoebe
Band-tailed Pigeon
Red-masked Parakeet
Western Wood-Pewee
Turkey Vulture
Hummingbird, Selasphorus
Black-chinned Hummingbird
Black-headed Grosbeak
--- John Beckett
Respectfully submitted,
Alan Cummings
10/1/12
http://birdwalks.caltech.edu/index.html
8/20/12
First, I deal with the hottest fact and then move
on to hard and cool. What is the hottest fact?
It's August. Noon in August is likely to be on
the warm side and, if the day is also on the
humid side, it can be genuinely unpleasant. The
hard fact? Except for black-chinned hummingbirds
and the odd flycatcher heading for monsoon midges
in Mexico, there are few potential migrating
birds passing through. Nor is there much in the
way of arriving wintering birds. A possible
exception is the possible onset of a new short
distance migration of mountain chickadees into
our area for the winter. If we keep seeing
chickadees, I'd say it's a lock. On the other
hand, we have lost some year round residents of
the San Gabriel valley, like the red-crowned
parrots that have moved to local food sources
outside campus, in effect, a short distance
migration away from us. Even if you are a bird
sticking it out with us throughout the summer,
you are probably not moving around any more than
you have to at noon. Overall, opportunities on
the avian front are weak in August. Birding is
also a matter of eyes and ears; Caltech birders
often migrate to vacations or conferences in
August. Even the ones who stay on campus are
often sessile due to the excessive heat. So it's
fewer eyes and fewer feathers. It's the abyss
of summer.
The coolest fact? August doesn't last forever.
We are at week 34. Next week (week 35), the high
is 21, the freaky sanctified residue of what had
to have been an extraordinary day in 2002, when
every resident bird in the area must have decided
to fly forward and be counted (apart from that
21, 16 would have been the high). However,
counts rise rapidly from there. Starting with
week 37, the migrators will be arriving.
Starting with week 37, the record highs are all
above 20 until week 23 of next year. Starting
in week 37, potential becomes more than nascent,
the weather cooler. The birders are out and the
birds are in. Of course, opportunity is not
fruition. Week 37 also holds the all-time record
low of 6 species but I'll take my chances.
I suppose that I need to talk about this week's
walk. It was actually not uncomfortable. It was
not a one-liter day (I tend to define difficult
birding days as those requiring the consumption
of a liter of water or more as soon as I get back
to my office; this is usually a phenomenon
reserved for 95+ F weather). Ok, it was a
little toasty but we had a perfectly respectable
mid-August species acquisition with 15 birds. We
were well above the minimum (9) and median (13)
for the week but no threat to the record of 18,
which was set last year.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
There were a variety of minor highlights. We saw
an acorn woodpecker on a palm tree near Wilson
and California. We have been seeing these birds
on the other side of campus off and on, lately,
but not near Wilson. This could be a juvenile
from the family whose territory is centered off
campus across the street from Hill, which would
be nice because it gave us the species for the
day, but not exciting. Based on the crown, our
bird was either a juvenile or adult female. If
we are lucky, this bird is exploring on behalf of
a family residing on the Pavilion's side of
campus. Two families, even off campus would
significantly increase our opportunities for
seeing this species going forward.
Lesser goldfinches were abundant on this walk,
especially in Tournament Park, where there was a
lot of begging going on. In July and early
August, lesser goldfinches become harder captures
because they are in breeding mode. Later in
August, however, fledged juveniles learn the
rules of the flock and how to make a living. The
flock, essentially a roving nursery school, is
raucous and visually flamboyant. I should also
mention chickadees again. We intersected at
least three more chickadees this week, at least
two in Tournament Park, leading to three
virtually simultaneous independent IDs based on
vocalization. Nobody saw them. We didn't see
Jason's bird near the ticket office, but we did
pick up another vocalization near Ramo near the end
of the walk. This makes last week's sighting an
official non-fluke. We now have eight chickadee
sightings for the year, which is approaching the
total of eleven we got last year, which exceeds
the total of nine we had captured over the
preceding couple of decades.
We had a three-hummingbird day, which is about as
good as we can hope for. We do get identifiable
adult male rufous hummingbirds occasionally but
not today (we lump female/juvenile rufous and
female/juvenile Allen's hummingbirds under the
catch-all of Selasphorus because these birds
can't be readily distinguished visually; blood
tests are good for id but that's not usually
practical). There are also a couple of
hummingbirds not on the Caltech list that we
could, in principle, see. Broad-tailed
hummingbirds are basically Mexicans but they can
be seen with some frequency in parts of Colorado
and New Mexico (the only state where I have
knowingly seen one). They are quite rare west of
the Sierras, so it's not surprising that they
haven't made our list. Costa's hummingbirds, on
the other hand, are seen locally. I saw one on
Colorado Blvd near Wilson, of all places,
although that was many years ago. They also
occur at the Huntington Library, which is quite
close to campus. Costa's hummingbirds must have passed through
campus at some point since 1986 but, apparently,
they don't like to do it on a Monday between noon
and 1 PM.
I don't know that I would call it a highlight but
we did have an unusual sighting on Wilson just
north of California. It was a loose ball flock
of white birds heading south south east. A quick
glassing made it clear that these were not snowy
egrets but a flock of ten or so white rock
pigeons. These birds were likely released as
part of a local marriage or memorial ceremony and
were heading home (this didn't have the numerical
flavor of a sporting event). There is a couple
(Nelsons') in Hacienda Heights who specialize in
"white dove" releases that would be consistent
with the orienteering of this flock.
http://www.whitedoverelease.com/ but the birds
could belong to some other LA basin aviary. The
Nelsons' site has some nice videos of "dove"
releases and it's a pleasant site overall but, if
you are interested in this type of service, I
would advise you to shop around because there are
other dove release businesses in the area (i.e.,
don't take my selecting their site as a
testimonial).
All of the white doves in our flock were, of
course, fake doves (they are rock pigeons) but
who cares. I think a suspension of belief
entailed in releasing white pigeons instead of
white doves is in order. They are a symbol Ovid
could have written about. They are a moment of
passage. They can carry ghosts. They can bless
babies. They have their place. True doves are
not homing, so a release is a death sentence
(otherwise there would be the odd feral
populations of white and partially white doves
and you never see them). Rock pigeons bred white
are a renewable resource because they will home
to their coop after being released. Yes, the odd
one will die along the way but you are
essentially renting them out for your ceremony
and the recovery rate is quite high.
When I started this report, I thought I was going
to spend a lot of time talking about tiny
magnetite crystals and how they impact the
ability of migratory birds (and pigeons) to tell
direction. Now, I'm not so sure. The
interaction between magnetic fields and tissue
got some seriously bad press in the eighteenth
century because Franz Mesmer popularized the
concept through a suite of miraculous cures (yes,
he's the source of the word mesmerizing).
Mesmer's extreme level of animal magnetism was
debunked but his case so biased people against
the idea that animals might be able to sense
and/or respond to magnetic fields that it wasn't
until the 1940s that the possibility resurfaced.
Rock pigeons have a working magnetic compass and,
sufficiently close to home, a visual and,
perhaps, olfactory map. You can tell that there
is a magnetic component because you can confuse a
bird's compass with magnetic pulses. The rock
pigeon subjected to this treatment will find true
north in the wrong direction. Eventually, he
figures out that the magnetic signal is giving
him garbage, inconsistent with other cues (e.g.,
sun direction), and he proceeds to ignore it.
Similarly, if you release a homing pigeon near a
local (natural) magnetic anomaly that he has
never encountered before, he will fly up or down
the field lines of the anomaly for a while,
sometimes for multiple kilometers, before he
figures out that this is not the direction
imposed by the larger scale magnetic field for
the Earth.
So, rock pigeons can respond to a
magnetic field and its intensity. The question
is how do they do it. There are tiny magnetite
crystals in 1-2 micron clusters in the upper beak
of rock pigeons along nerves. These crystals
will align with a magnetic field and one can
reasonably surmise that if this alignment can be
signaled to the bird's brain by a nerve, you
would have the basic mechanism for an internal
compass. However, recent work suggests that
these magnetite crystals are actually in
macrophages, which are big cells designed to eat
junk in blood and initiate anti-pathogen
responses by other cells; they are not directly
attached to the nerve structures and, therefore,
they are probably not participating in a magnetic
compass for the bird. This is one of the beauties
of science. What is obvious and Eureka-like in
2003 is challenged in 2012. Lots of tiny
magnetite crystals a few nanometers in diameter
dutifully jangling a bird's nerve as your
orientation veers from a north-south magnetic
plumb line, which is intuitively satisfying,
suddenly become part of the bird's health defense
repertoire. That doesn't mean that the standard
model is wrong (if you cut that nerve, the bird
loses its compass). It just means that we aren't
finished looking at the problem. Magnetite
crystals outside the macrophages may be the
answer, or not. After all, we have millions of
magnetite crystals in our brains and there is not
much evidence for humans migrating along magnetic
field lines without the help of a magnet
(although some of those out in the middle of
nowhere dead reckoning open boat navigator
stories make you wonder). One can certainly
conceive of the vast majority of the magnetite
crystals in a bird being irrelevant but a few
crystals posed properly being the key to an
internal compass. Just to muddy the situation
some more, I should also mention the possibility
that certain chemical reactions associated with
pigment cells in birds are sensitive to magnetic
fields. This research is, however, at an early
stage where the focus is on demonstrating that
the mechanism is possible, not that it is the
basis for magnetic compasses in animals. Stay
tuned.
The date: 8/20/2012
The week number: 34
The walk number: 1157
The weather: 90°F, sunny
The walkers: Alan Cummings, Melanie Channon, Viveca Sapin-Areeda, John Beckett
The birds (15):
Rock Pigeon
House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
Acorn Woodpecker
American Crow
Lesser Goldfinch
Black Phoebe
Black-chinned Hummingbird
Turkey Vulture
Mountain Chickadee
Band-tailed Pigeon
Bushtit
Hummingbird, Selasphorus
--- John Beckett
Respectfully submitted,
Alan Cummings
9/9/12
http://birdwalks.caltech.edu/index.html
8/13/12
Week 33 has the honor of the lowest high of the
year with 14 in 2010. This week, it seemed for a
while that the issue of the day was not whether
or not we were going to threaten that lowly high
but whether or not we were going to threaten the
lowly low for the week, which is 9 (2008). In
the end, however, we could claim an even dozen
species, which lies above the median of 11 for
the week.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
We were almost better by a bird. Near the end of
the walk, Jason peels off the walk route so he
can check on potential housing (he's currently
"homeless"). About five minutes later, he
returns to the walk route as he ambles back to
his office and, in so doing, he catches sight of
an acorn woodpecker in a palm tree off Holliston.
Now, Viveca and I, who were the last members of
the official walk, know this woodpecker. We have
been seeing him off and on over the last several
weeks and we were certainly looking for him as we
walked down Holliston but we didn't see him.
Jason does see him and the woodpecker would be
species number 13 for us, if we could accept him.
Could we? There are rule and rules. The Caltech
bird walk species count is constructed from three
sources. First, there are birds identified along
the official walk route. We also accept birds
that walkers see in transit between their office
and the walk starting point across from Cahill.
The rule is that the walker and/or the bird must
be on or above Caltech property and that the bird
must be sighted on a trip from the place you were
at just prior to going to the walk. So, if you
left your office and saw four birds as you walked
to Starbuck's, two of them on Caltech property,
picked up a coffee, walked back from Starbuck's
along California, seeing three more birds in
nonCaltech trees before you got to Wilson, and
therefore Caltech property, and then saw one bird
as you walked by Spalding to the walk starting
point, only that last bird could be used. A
similar rule applies to a departure from the
walk. Once, you leave the walk, any bird seen on
or from Caltech property is legal until you reach
your first destination, whether that is your
office or the Housing Office, or you leave
Caltech property, whichever happens first. In
this case, Jason saw the acorn woodpecker
after he had completed a first outbound leg after
departing from the walk. After that, he was
still on Caltech property as he rejoined the walk
route but he was officially off the walk (unless
he had caught up with us) because he had already
reached his first post walk destination.
Finally, I arrive in a frisson, brought to you by
Jason Price. We are approaching the Caltech
ticket office when Jason claims to have heard
a chickadee. We only get one kind of chickadee
around here, so this was tantamount to making a
call for a mountain chickadee. Now, I didn't
hear it (I need to be within 5 or 6 meters) and
Viveca didn't catch it, which put us into
confirmation mode. We spend a couple of minutes
trying to pick up a visual from across the street
with no luck, so we cross the street and converge
under the target trees, looking for Jason's
bird. We had a serious problem. There were
bushtits everywhere. Our bushtit flocks had been
getting skimpy because pairs (and threes - there
are commonly unrelated male helpers) had been
leaving the flock to breed but it looks like they
are now back in force and reinforced with some
newly fledged birds. Seeing one potential
chickadee amongst 60 bushtits is a nontrivial
exercise. It took several minutes of failing to
unravel the crowd before the crowd began to
unravel itself. The bushtits were gradually
heading north while the chickadee was gradually
heading south. Finally, we all registered brief
but unambiguous glimpses. We had our first
mountain chickadee of the season and our seventh
chickadee sighting of the year.
2011 was an extraordinary year for chickadees
because we had eleven sightings, all after week
33. In previous years, chickadee sightings were
sporadic, only nine altogether, only one in any
given year, except for 1987 when there were two
sightings on successive weeks (i.e., potentially
the same bird) and in only eight years between
1986 and 2010 (i.e., chickadee sightings were a
once in every three year or so event). In
2011-2012, we had an explosion of sightings,
starting with a Tournament Park bird in week 35
of 2011 and extending to week 16 of this year.
We had 17 sightings in 33 weeks, a classic
overwintering species profile. That's once every
couple of weeks instead of once every three years
or a 52% rate versus a 0.8% rate. The key will
be whether or not the residence of last winter,
which involved at least several different birds,
is going to be repeated. I'm not ready to get
overly excited, yet, because juveniles disperse
from breeding grounds in August and September.
So, it is possible that we just had one of those
rare juvenile chickadee sightings but, if this
bird is part of a newly established phenomenon,
we are going to be seeing a lot of chickadees
over the next few months and if the sightings
rate is anything like it was last year, we should
have a new record for chickadee sightings in a
calendar year (we already have seven so far this
year and the eleven sightings of last year were
all between weeks 35 and 52). Mohammed may have
had to go to the mountain but the mountain
chickadees may be coming to us. If so, the new
harbinger of Fall may not be the kinglets and
yellow-rumped warblers coming in a couple of
months from far north of us but rather a local
migrator coming out of the San Gabriel mountains.
I have hopes that Fall will come in August and
spin the Summer down.
The date: 8/13/2012
The week number: 33
The walk number: 1156
The weather: 93F, sunny
The walkers: Alan Cummings, Jason Price, John
Beckett, Kent Potter, Viveca Sapin-Areeda
The birds (12):
Northern Mockingbird
House Sparrow
Mourning Dove
Anna's Hummingbird
American Crow
Band-tailed Pigeon
Common Raven
Hummingbird, Selasphorus
Black Phoebe
Bushtits
Mountain Chickadee
Red-masked Parakeet
--- John Beckett
Respectfully submitted,
Alan Cummings
8/17/12
http://birdwalks.caltech.edu/index.html
8/6/12
It was a walk of no. There were no caws
gathering the multitude, no cackles, no begging,
no crows, no sailors in the sky, no ravens, no
vultures, no hawks, no falcons. There was no
chirping siesta from a sparrow, no towhee, no
pigeon, no goldfinch, no wren, no starling, no
jay, no mocking bird, no warbler (well that one
was not unexpected), no keys. It was also a walk
of ones. We saw one mourning dove, one mallard,
one black phoebe, and one house finch. We heard
some red-masked parakeets but we didn't see them
and we saw several hummingbirds although I didn't
hear them. It was hot. We confronted a hot
laden, gripping heat at noon and it only got
worse as the walk unfolded. We were cast us like
shrouded wrecks along a transom path churning
little in our wake. Did I mention that it was
hot? Alan hopped from shade to shade. I'm sure
that I looked wilted. I blasted through a liter
of water when I got back. Kent managed to
maintain a dapper look, somehow. The secret must
lie in the beard.
It was a walk of almost. Alan misplaced his
Maintenance yard keys and, had I not gone over
the main gate and Kent through the side gate, we
would have missed our one mourning dove. Had
somebody walking away from the parking structure
not flushed a house finch just as I was walking
up Wilson, we would have had no finch. Had Alan
not seen the black phoebe, we probably wouldn't
have acquired one of them either. We were but a
whisper from sliding down the bowels of tough
birding to that ugly place where there awaits the
all-time record of six bird frustration set in
week 37 of 2006. As it is, we closed with a
tally of eight, tying walks of 2001 and 2004 for
the worst species totals ever for a week 32 bird
walk.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
On a much brighter note, Kent Potter has just
passed Glenn Hamell for career bird walks and is
now in sole possession of second place with 356.
Kent has been taking in the walk at a fairly
steady clip since 2001. Among currently active
nonAlan walkers, only Viveca with 214 career
walks can be mentioned in the same breath but, if
Kent stopped walking today and Viveca made every
walk going forward (keeping in mind that nobody
has ever done more than 48 walks in a year), it
would 2015 before she could possibly catch him.
Of course, to put things into perspective, if
Alan stopped walking today, not even Kent could
hope to match his career total in walks before
2025. I can only say that I wish Kent many happy
returns.
Choosing a highlight bird for the week seems
almost morbid but I will, out of near necessity,
select the Anna's hummingbird. We had a pleasant
time looking at the multi-feeder house just
outside Tournament Park, where we saw a numerous
Anna's and Selasphorus hummingbirds on or around
the feeders. There was also a possible
black-chinned hummingbird but the feeders are
rather far away from the fence, the birds are
small, and nobody had a spotting scope. I would
be willing to say that it was more likely than
not, just based on form but we just couldn't pull
the trigger on a positive identification.
The word for bird is water. It is the essence of
life and birds, as is true of any other creature,
must acquire what they need directly through
drinking or through their prey. The word for
hummingbird is river. An Anna's will consume its
weight in water every 15 hours or so, on average.
An Anna's lives on nectar (or sugar water from a
feeder) when it can but insects make up a
substantial portion of the diet, particularly at
certain times of the year. Like many birds, a
female Anna's manipulates protein delivery in the
diet of her young (males are occasionally
observed feeding young but it's not typical or
even uncommon). During the morning, the
nestlings (almost always two) get nectar and the
odd insect that their mother happens to run into,
but later in the day she switches, providing a
much higher insect to nectar ratio even if nectar
is readily available. Why? It's all about
energy. Sugar is a Roman candle energy source
and carbohydrates, which are also available from
nectar to some extent, are inefficient for
hummingbirds, certain human diets
notwithstanding. Protein has staying power and,
if you don't want your nestlings to starve in the
dark, you want them to build up a reserve in the
afternoon. So, you let your local insects run
rampant in the morning and you suck them up in
the afternoon.
Anna's are decidedly territorial and have been
expanding range through their ability to take
advantage of urban sprawl and its explosion of
exotic backyard flowers and feeders. These are
often rich territories and Anna's are very good
at defending rich territories. For several
years, a single female Anna's owned my property,
both in the front and in the back yard. I don't
put out feeders but she vigorously defended our
fuchsias and drove off all other hummingbirds,
except that she would tolerate her own young for
a week or two after they fledged. She had
favored perches that varied with time of day and
season and I could almost always find her within
a few minutes if I was so inclined. In the late
Spring, when our river silk tree bloomed, she
would try to defend the entire tree but after a
couple of days, she would give up and allow any
hummingbird who wanted it, unfettered access to
the tree (she continued to defend the fuchsias in
front). I must admit to being rather fond of
her. I am sorry to report that she died in the
great windstorm and her empire seems to have been
split, like Alexander's. There are now two new
Anna's on my property, one in front, a female who
also owns the yard across the street, and another
in the back. I do not seem to have bonded with
either of them, so far. Perhaps, it's part of
the "grieving" process.
Ravens are the intellectual giants of the avian
world and other corvids like crows are certainly
not stupid. Anna's hummingbirds are, shall we
say, on the other side of the intellectual
spectrum. They depend on hard-wired responses to
environment and this obviously works most of the
time but it can also get them into trouble. For
example, an Anna's will respond to a serious
threat by flying straight up and, if there is
something in the way, she can't revise the
security arrangement by going sideways. This
leads to hummingbirds getting stuck in the
rafters of garages. Even though there is a huge
opening available to the bird, it will not be
able to escape. It will starve in there because
it can't turn off the threat response. Only you
can help. There are many on-line suggestions,
should you have this problem, ranging from
putting a feeder at the mouth of the garage to
entice the bird down, to using a pool net to
exhaust the bird, so that it is forced to drop
down to the ground where you can then drive it
out so that it "escapes you", to darkening the
garage, which forces the bird to drop to the
ground, where you can scoop it up (you will,
hopefully, have remembered to bring a flashlight
for this exercise, and take it outside.
The male's dive display (fly up 20 or 30 meters;
make sure that your gorget glints in the sun;
dive down next to your display objective singing
as you go; come out of the dive about a meter
away from it, whipping your tail as you go by to
produce a sharp click at the bottom; hover to
make sure that your performance is being
appreciated; and repeat as needed) is another
example of a hard-wired response. It's a great
attention getter but the male doesn't always
manage to choose a female Anna's for a courtship
display. Even I have been the object of a male
Anna's affection and I weigh significantly more
than 4 grams. Still, there is something to be
said for a bird wanting to zip by you at 60 miles
per hour. If you think about it in terms of the
rate of speed per unit body length, that's double
the best for a peregrine falcon, even though the
peregrine is the fastest bird alive in terms of
raw speed.
The date: 8/06/2012
The week number: 32
The walk number: 1155
The weather: 94 F, sunny
The walkers: Alan Cummings, John Beckett, Kent Potter
The birds (8):
Mourning Dove
House Finch
Anna's Hummingbird
Mallard
Hummingbird, Selasphorus
Red-masked Parakeet
Bushtits
Black Phoebe
--- John Beckett
Respectfully submitted,
Alan Cummings
8/11/12
http://birdwalks.caltech.edu/index.html