10/29/12
Some walks are open fields with salients rising
like minarets above the patterned flow of the
mundane. The towers allow no subtle parsing.
You are almost compelled to fill the opalescent
flask of a memory and mix in spices to sprinkle
on lesser times. This was the tide of our week.
The field contained 21 species, which sounds
pretty good. It is pretty good but it is not of
special note. We saw more species in four other
week 44 walks including the record of 26, set
last year. Still, the median is 17 and the low
11, so we are in no position to complain, even by
the raw sourcing of a species count. The harbor
of special birds was, however, filled with
anecdotal joys. We had three first time avian
appearances for the season, a second time birder
(Agnes), and a pleasant crowd including Ashish,
who brought his patented cherub smile although he
seemed almost naked without his camera. It was a
nice walk.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
I will play favorites in describing highlights.
The Say's phoebe in the playing field deserves a
note. We seem to have missed the initial week
40-41 pulse of Say's phoebes passing through town
and we are now seeing some of the migratory
laggards. These birds typically stay around the
playing field for a few days with visits often
extending up to a week or two. Occasionally,
perhaps four or five times since our first Say's
appeared in 1999, a bird will decide to stay for
a month or more and we get a lot of successive
sightings. Unfortunately, this does not usually
happen with the first bird of the season, so I am
not overly hopeful that next week will yield
another Say's.
A Say's phoebe is always welcome but the most
spectacular bird of the day was also the last
bird of the day. We were walking up the path
winding around the Throop ponds, hoping for a
wren, when Viveca instead notices a dove/pigeon
sized bird engaging in some desultory pecking
along a branch overhanging mallard pond. This
seemed very odd behavior for a mourning dove but
the dove soon morphed into a female northern
flicker. She is not nearly as flashy looking as
a male but there is still a lot to see in this
bird and she offered a fairly patient pose before
flying off without finding a suitable meal.
Northern flickers are winter birds for us. We
have a few sightings from August but 90 per cent
of our sightings are encompassed between weeks 42
(late October) and week 12 (late March). It's
also fair to say that the sightings data are
distorted by some unusually flicker rich years.
We've had 58 northern flicker sightings on the
Caltech bird walk, which might make you think
that they are not super rare, but more than thirty
of those sightings came between 1988 and 1993.
In the last decade, we have claimed only 13
flickers, making it a once or so every year type
of bird but, even here, the counts are
misleading. We had pulses of three and four
sightings in 2009 and 2011 but none in the years
2005-2007 or 2010. Since flickers tend to be
somewhat talkative and the birds are neither
small nor shy, I think it fair to say that we catch
a lot of the available flickers and that there
just aren't a lot of these birds on campus.
I have yet to speak of our bird of the week. It
comes in a smaller, less flamboyant package than
the flicker but it is no less welcome. As the
group approaches Wilson, Viveca wanders into the
Morrisroe garden. Vicky and I, lagging behind,
arrive at the corner of the fencing looking into
the garden just in time to see the curious head
of a dark-eyed junco. Viveca, who was by now on
the inside looking outward, got a much better
view. We had a dark-eyed junco. Dark-eyed
juncos have been active up in the foothills for
some time but this is the first junco of the
season for the Caltech bird walk.
Dark-eyed juncos are strictly winter season birds
for us. Every sighting but one lies in the range
defined by week 42 (late October) in the Fall and
week 13 (late March) in the Spring (in 2010, we
had one anomalously late sighting in week 17).
The bulk of the sightings come from week 49
through 12 (i.e., early December through late
April). From a year-to-year perspective,
dark-eyed junco sightings on the Caltech bird
walk are episodic. The sightings have come in
three pulses, 1986-1991 (16 sightings), 1996-1998
(3 sightings), and 2004 - present (37 and
counting), so that the general pattern seems to
be one of sightings for some number of successive
years followed by four or five years of juncoless
walks. If we were doing walks up in the
foothills, there would be variations in the
number of sightings but juncos would be sighted
every year. So, it seems likely that one factor
encouraging a junco to think about Caltech is a
stress in habitat further upslope. A second
important consideration is the quality of sparrow
habitat on campus. If we had a bad year for
house sparrows, which I take to be an indicator of
sparrow habitat quality, we had a bad year for
juncos. Taking apart a recent spurt in junco
sightings that is likely driven by the Station
fire, less than 40 house sparrow sightings in a
year meant no juncos. I admit to our seeing one
dark eyed junco in 1998 when there were only 38
house sparrow sightings but, to me, that is no
more than an exception to emphasize a rule.
During the breeding season, dark-eyed juncos are
socially monogamous birds leavened in a thick
frosting of lothario. They were classically
thought to be monogamous, both socially and in
reality but DNA testing shows that 20 or 30 per
cent of female juncos engage in affairs leading
to progeny. The females socially mated to males
that have affairs (aka the lotharios) almost
never have affairs of their own and the males
whose mates have affairs almost never engage in
affairs themselves or, perhaps I should say, they
are rarely successful in any affairs they might
attempt to engage in. This is a curious
dichotomy. One would think that a lothario off
hunting for potential affairs would be
susceptible to having his mate engage in them
behind his absence. However, it doesn't seem to
work that way in the junco world. A lothario
will sneak into a nearby territory near dusk,
dash in for a quick frolic, and dash back to his
home territory. This may be timed perfectly so
that a rival is unable to claim a similar
visitation with his mate. However, a lothario's
breeding success may be a reflection of
extraordinary fitness, so his mate, even given
the opportunity to breed with a less fit male,
will choose not to. Nevertheless, there may well
be a hidden cost for our lothario. The time he
spends trying to set up liaisons with the
neighbors is time not spent caring for the
progeny of his social mate. This can lead to
lower fledging rates so that his overall
reproductive success may not be much better than
if he had just stayed home.
The date: 10/29/2012
The week number: 44
The walk number: 1167
The weather: 82 F, sunny
The walkers: Alan Cummings, John Beckett, Kent
Potter, Viveca Sapin-Areeda, Ashish Maharbal,
Vicky Brennan, Agnes Tong
The birds (21):
Mourning Dove
House Finch
Anna's Hummingbird
Acorn Woodpecker
American Crow
Lesser Goldfinch
Black Phoebe
Mallard
European Starling
Yellow-rumped Warbler
Western Meadowlark
Say's Phoebe
Bushtit
Ruby-crowned Kinglet
Dark-eyed Junco
California Towhee
Townsend's Warbler
Common Raven
White-throated Swift
Hummingbird, Selasphorus
Northern Flicker
--- John Beckett
Respectfully submitted,
Alan Cummings
11/21/12
http://birdwalks.caltech.edu/index.html
10/22/12
This was not a spectacular walk with rare birds
dripping from every branch. Nor did we see any
extraordinarily rare birds. We were, however,
dripping in time as a wave of season swept
through and around us. We were dripping in the
season. By the numbers, our total of 20 species
was just three below the record of 23 set in week
43 of 2005 and well above the median (16) and
minimum (10).
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 all sorts of highlights. We didn't
see any rare birds but we did have the season's
first sighting of a ruby-crowned kinglet, the
season's first sighting of a cedar waxwing, the
season's first sighting of an American goldfinch,
and the season's first sighting of a rufous
hummingbird. Were it not for a single confused
juvenile rooting through the bushes outside Braun
last week, it would also have been the season's
first sighting of a white-crowned sparrow. These
birds are a binding tessellation. They outline
our seasons and guard the boundaries of cold and
rain. Left to our own devices, we might wait
until a cold snap or Thanksgiving to declare the
Fall but the birds know better and the cacophony
of their arrival is the mark of the season. The
Fall is here.
Perhaps, the most revelatory sighting of our walk
was a ruby crowned kinglet in the Maintenance
yard. It was rooting through the fence bushes on
the north side, moving fast and gleaning faster.
Generally speaking, kinglets are in a hurry to
live. Do the math. If the total population is
stable, and you are in one of 12 eggs, the odds
of your surviving to your first birthday are not
in your favor. Kinglets carry a heavy mortality
load through life but they seem determined to
make the most of it.
During the breeding season, kinglets look for
mature high canopy spruce and ponderosa pine and
relatively dense cover. This means that logging
and fires are bad news for kinglets and riparian
buffer zones need to be really wide to be useful,
much wider than loggers are willing to
contemplate. In the winter, kinglets are much
more cosmopolitan. They are partial to our oaks
but you can find a kinglet in almost anything.
If you have roses, kinglets are your friends.
Forget the soapy water. I've seen a kinglet
vacuum his way right up an aphid encrusted
branch, drop a few centimeters, move 30 or 40
degrees and vacuum again, repeating several
times. Forget the dormant oil. My aphid problem
disappeared in a week's beak and no toxicity.
Ruby crowned kinglets are a reliable marker of
the Fall, generally arriving a week or two after
yellow-rumped warblers (they leave the breeding
grounds a week or two after the local warblers)
but this is a sliding target. In the early 90s,
we were seeing them as early as week 39 and,
between 1989 and 1997, the average was week 40.
Since then, we have generally been picking them
up a little later in the year (the average is
week 42), although the distribution is more
scattered. So, a first sighting of the season at
week 43 is consistent with the modern paradigm.
I'm not sure what the modern paradigm represents
but, given that kinglets are pretty easy to pick
up when they are around, this seems to be a real
effect. There are more Caltech birders on
average now than there were in the 90s and
kinglets are not hard to find when they are
around. Yet, we are seeing kinglets coming in
later. One possibility is that the kinglets who
like to winter on campus are in fact coming in
later but this doesn't explain the scatter. Our
last Spring sighting has held fairly steady,
around week 13, only once (1997) extending beyond
week 15. So, I'm inclined to think that our
principal winter residents have been arriving
around weeks 42 or 43 all along. Another
possibility is that we are not always seeing
juveniles, who generally start south a week or
two before the adults. Had big deficits of
juveniles been occurring throughout the last
decade, there wouldn't be any kinglets at all by
now. However, we could be seeing some stress on
the general population, even though kinglets in
the west are supposedly stable or even
experiencing a mild population increase. If you
have a good year, you have lots of juveniles
wandering through campus around week 40 or 41 and
we see them. If it's a bad year, we may miss
them. By this theory, the 90s were very good for
kinglets with lots of juveniles and the last
decade has been much less successful.
Unfortunately, juvenile ruby crowned kinglets
look like adult male kinglets who look like adult
female kinglets unless you happen to catch one in
an excited state. So, we can't establish
variations in sex or juvenile versus adult ratios
by arrival time or residence (the situation is
also complicated because kinglets segregate by
sex in their wintering ranges - males tend to get
the good territories and winter further north on
average).
Now, since I don't actually know what the reason
behind the scatter in first Fall kinglet
sightings is and I don't have much data to work
with, I will paper mache another possible natural
history for you. Perhaps, we have two
populations of Fall kinglets, one composed of
wintering residents that stay on campus and
another that passes by a week or two earlier.
This latter population experienced a significant
decline in the late 90s. This is not a sign of
the extirpation of breeding kinglets in the San
Gabriel Mountains. They were gone by the 1980s.
Nor would we see evidence for this population in
the Spring statistics. A migrating kinglet
passing through campus on his way back north, a
week or two before our kinglets leave, would be
confused with a winter resident. We still have
early sightings in the Fall (it was week 40 in
2010), so these putative rare birds are still
with us, which is one reason, I think we may be
seeing a muted reflection of the year's breeding
success (i.e., we are catching or not catching
juveniles). The increased scatter in first Fall
sightings in recent years reflects whether or not
we manage to catch the through traffic heading
south and, I would assert, whether these are
adults from some region of Canada heading to
Mexico or juveniles from the same breeding areas
as our wintering adults, that there are often
fewer of them to see.
The date: 10/22/2012
The week number: 43
The walk number: 1166
The weather: 67 F, partly cloudy
The walkers: Alan Cummings, John Beckett, Melanie
Channon, Vicky Brennan, Viveca Sapin-Areeda
The birds (20):
Scrub Jay
Northern Mockingbird
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
Red-tailed Hawk
Common Raven
Yellow-rumped Warbler
White-throated Swift
Lesser Goldfinch
Ruby-crowned Kinglet
White-crowned Sparrow
Wren, species
American Goldfinch
Band-tailed Pigeon
Orange-crowned Warbler
Black Phoebe
Cedar Waxwing
Hummingbird, Rufous
--- John Beckett
Respectfully submitted,
Alan Cummings
11/19/12
http://birdwalks.caltech.edu/index.html
10/15/12
For me to hold a day to yesterday, I have to
grasp a sere cloud in a blue sky and look for
rain. I have to see an afterglow in a passing
thought and conjure mysteries. I have to be
within a spatial pattern's gloss. I see the
petals of birds in the ashes untied to the images
and sounds of any particular week, although I do
have a sense of season and what was seen and
where over the last few weeks. This time, we
have another 20 species walk with a passing
resemblance to last week. We saw one meadowlark,
not four but that still counts for a two
successive weeks of meadowlarks. Barbara brought
along a friend, Karen Scauzillo, who is our 133rd
new walker. I don't know when the last time we
had new walkers come in successive weeks but it
must be rare, at the least, a once every few
years type of event. Yellow rumped warblers were
not rare but our corvids decided to be scarce.
We didn't hear a single crow and failed to see a
raven but we did pick up a solitary white-crowned
sparrow, the first of the season and, for the
first time in a couple of years, a red-naped
sapsucker. Our snowy egret sighting counts as
the most anomalous snowy ever for reasons I
describe below.
The final tally of 20 species is comfortably
above the median (16) and minimum (9). We were
well below the record of 29 observed in 2010 but
our species total was the fourth most in week 42,
after 2009 (21), 2011 (25), and 2010 (29). This
is another way of saying that the top four week
42 species counts for the Caltech bird walk are
from the four most recent week 42s. It kind of
reminds me of global warming.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
Our most unusual sighting has to be the snowy
egret. We have had 29 snowy egret sightings on
the Caltech bird walk over the years but these
are all bunched in the winter/Spring, weeks 50
through week 16, and episodic, occurring in only
seven different years, although three of those
are the current and previous two years. A week
42 snowy egret sighting is by far the earliest we
have; we shouldn't be seeing one of these birds
for another couple of months, if then. We will,
however, take what we can get. If we see this
bird next week, we will be tied with 2002 for the
most snowy egret sightings in a calendar year
with nine. It's a pity that we can't band these
birds. It would have been interesting to know
whether we are seeing one individual using
Caltech as one of his collection of fishing holes
over the last couple of years or multiple
individuals that happen to stop by at odd times
in the winter and Spring.
As interesting and unusual as the snowy egret
was, the bird of the week has to be the red-naped
sapsucker who, as Viveca and I were walking along
Holliston Ave., flew directly over our heads and
landed in a tree about 15 meters in front of us.
He chose a well exposed perch and stayed there
for several minutes, long enough for Alan to loop
back and get a good look of his own. This was
our fifteenth sighting of a red-naped sapsucker.
With the exception of one seriously confused bird
from July of 2009, presumably a juvenile, all of
these sightings come between weeks 41 and week 13
with pulses in weeks 41-44 and 5-8. Our two
sightings of a red-naped x red-breasted hybrid
also came within one of these pulse periods
(weeks 41 and 43). Sightings of red-breasted
sapsuckers (14 total) appear to be more wintery,
coming mostly in weeks 47 through 13.
We are on the extreme western edge of the
red-naped sapsucker's wintering territory, so
observations are possible anytime in the Fall,
after week 40, through the Spring but most of our
birds are probably in the process of migrating to
Mexico for winter or to the Rockies or Sierras
for the breeding season, although there are some
isolated breeding populations in southern
California mountains.
Before mitochondrial DNA came on to the scene,
the sapsucker speciation world could only be
described as confused. Everybody thought that
Williamson sapsuckers were something different
but after that, trouble came in bunches. Were
sapsuckers one superspecies composed of
yellow-bellied sapsuckers, red-naped sapsuckers
and red-breasted sapsuckers or three separate
species? There were clear but restricted
hybridization regions, which suggested separate
species, but there were also troubling aspects.
Female red-naped sapsuckers have an
unquestionable "lust for red" and hybridize with
male red-breasted sapsuckers, whenever the
opportunity arises, which happens not
infrequently in Oregon, northern California and
parts of Nevada. These unions fledge just as
many juveniles as their peers. The back crosses
don't do so well but this appears to be more
about prejudice than fertility. For decades, the
issue of speciation moved like a tide built on
the force of personality but, generally, the
sapsuckers were relegated to a yellow-bellied
red-naped complex.
So, what does the DNA say?
It says that Williamson sapsuckers are quite
different from yellow-bellied, red-naped, and
red-breasted sapsuckers. Those old
ornithologists were no fools. Yellow-bellied,
red-naped, and red-breasted sapsuckers are very
closely related. Red-naped, and red-breasted
sapsuckers are so close that they represented the
most closely related birds still regarded as
separate species with a mitochondrial drift
suggesting separation of the populations occurred
less than a million years ago. However, even
with the DNA studies, separation into three
distinct species, which was officially accepted
in the 1980s by the American Ornithological
Union, was couched in a lot of "on balance"
arguments.
In discussing sapsuckers, the first point of
reference, even if it isn't the most obvious, is
that they are vitally important primary hole
nesters. They generally want a tree with heart
wood rot (aspens are particularly prone to this)
and they generally drill holes in the same tree
over multiple years, starting relatively low, as
low as a couple of meters, and working their way
up (you can think of heart wood rot as a tapered
cone inside the tree; the sapsucker is looking
for a particular combination of strong outer wood
with easily excavated rotten inner wood). Both
sexes exhibit strong site fidelity and,
therefore, a fairly strong mate fidelity.
Red-naped sapsuckers are willing to work with
snags (standing dead trees) but, unlike flickers,
they don't go out of their way to find them.
Since a sapsucker makes a new nesting hole every
year, he is providing nesting sites for a wide
variety of weak primary hole nesters like
chickadees and a host of secondary hole nesters
like tree and violet-green swallows, bluebirds,
robins, warblers and wrens that can't make or
modify their own holes. There probably isn't a
more desirable commodity in the life of a
secondary hole nester than a prime sapsucker
nesting hole.
A second and more obvious point of reference is
that sapsuckers drill for sap. If you go to the
eastern side of Tournament Park and look at trees
on the other side of the property line, you will
find one with prominent horizontal sets of holes
snaking up the tree. These are sap wells drilled
out by a sapsucker several years ago. I don't
know about this bird but usually a sapsucker will
start drilling sap wells low on the tree or a
branch and work his way up. Occasionally, they
will tear off strips of bark instead of drilling
wells but the effect is the same. The tree weeps
and the sapsucker sips and opportunistically eats
insects that have been attracted to the sap.
They feed the sapsucker making them but they also
feed several dozen other species, including
butterflies, wasps, hummingbirds, warblers,
squirrels, and chipmunks. The sapsucker will
defend his sap wells but it's not too hard to
work your way around his schedule. Sap wells are
a supermarket.
The date: 10/15/2012
The week number: 42
The walk number: 1165
The weather: 91 F, sunny
The walkers: Alan Cummings, Barbara Ellis, Karen
Scauzillo, Kent Potter, John Beckett, Vicky
Brennan, Viveca Sapin-Areeda
The birds (20):
Scrub Jay
Northern Mockingbird
Mourning Dove
House Finch
Anna's Hummingbird
Acorn Woodpecker
Mallard
Red-tailed Hawk
Lesser Goldfinch
Yellow-rumped Warbler
Western Meadowlark
Black Phoebe
Turkey Vulture
Spotted Towhee
Yellow-chevroned Parakeet
House Wren
White-throated Swift
White-crowned Sparrow
Red-naped Sapsucker
Snowy Egret
--- John Beckett
Respectfully submitted,
Alan Cummings
10/22/12
http://birdwalks.caltech.edu/index.html
10/8/12
We are back! We are back! We are back in the
twenties after four months spent toiling in the
teens (or worse in one case). There are now
birds to be had and birds to be seen, as if the
westerlies had suddenly swelled into our hearts
after months without a single fluttering sail
calling to the wind. It is the swell of marking
passages and new homes. The Fall migration has
arrived and the species count reflects it. We
ended up with 20 species on the nose, well above
the low of 12 and median of 16 and we also picked
up some meadowlarks along the way. The record
for total number of species in a week 41 walk is
24, set in 2010 and matched last year but who
cares. The twenties are back!
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
Next week the record is a rather formidable 29.
Ruby-crowned kinglets, white-crowned sparrows, and
hermit thrushes are plausible targets. We have
yet to see any black-throated gray or Townsend
warblers this season. Orange-crowned warblers
are around but, as yet, in low abundance. That
may change. Yellow-rumped warblers are around
and in high abundance, so high that a lot of time
is spent sifting through yellow rumps to see if
something different is among them. That will
hopefully stay the same.
We had two highlights for the day. The first was
a new walker, Agnes Tong. Agnes is our 132nd
walker and the second of this year, Richard Price
being the other. On the avian front, the
highlight bird of the day has to be a grounded
cluster of western meadowlarks in a rough patch
of grass in the outfield of the baseball field.
Meadowlarks are a sporadic, once a year sort of
capture for us, invariably in the grass of the
baseball field or track but we definitely have a
shot at more of them for the next month.
I offer a meadowlark conundrum for your
consideration and a couple of idle speculations.
I have no solution, although I expect that
somebody else in the group does. Week 41 is
easily our most common sightings week for this
species (9 of 27 sightings have come from week
41). So, our sighting this week is typical of
our record for intersecting this species. So,
where is the conundrum? It's too typical.
Twenty five of our 27 sightings are from weeks 39
- 45. Where do these birds come from and where
are they going? They generally don't stick
around Caltech for long, so we are just a brief
way station. Nor, at first sight, does this seem
to be a migration thing. It is true that
meadowlarks at high elevations move down and
birds breeding in the far north move south for
the winter. However, we have a Caltech pattern
of one big blast in October - November with no
corresponding pulse in the Spring. I also don't
see this as juvenile dispersal pattern as that
would likely show up a month earlier than we see
it and meadowlarks usually double clutch, so we
should be seeing multiple juvenile pulses if that
what was going on and we don't.
Just to get your
idle speculation juices flowing, I'll give you
some possibilities to eschew if you want to. One
is that our birds move in small flocks in the
Fall and large flocks in the Spring [we are more
likely to get a bird walk sighting if thirty
birds pass by in ten three bird flocks (e.g.,
Fall) than if they go by in one thirty bird flock
(e.g., Spring)]. Meadowlarks are known to form
large winter flocks. Another possibility is that
these birds are leaving some agricultural regime
that closes off in October (alfalfa?). Perhaps
the pattern of movement is somewhat analagous to
that of red-masked parakeets, always in the
general area, more or less, and hence resident.
However, they follow the food from place to place
and you end up with a seasonal distribution of
the birds if you stay sessile or walk the same
birding route every week.
OK, it's your turn.
Meadowlarks eat insects when they can, which is
basically Spring into summer, but will eat corn
or oats if none are available and this actually
got them into trouble at the beginning of the
twentieth century when farmers in California were
trying to get meadowlarks declared agricultural
pests so that they could slaughter them and get
the government to slaughter the birds for them
(the Mao approach to horticulture). However,
when they funded a study to prove how bad these
birds were for crops, the guy who did the study
discovered that meadowlarks ate a lot more
grasshoppers than seeds, ate more weed seeds than
crop seeds, and that they resorted to vegetable
matter (thereby putting on a seed eating and
sprout destroying show for Mr. Farmer) mostly
when they couldn't find an insect. On balance,
they were a beneficial for crops. The farmers
put their shotguns away.
For the factoid of the week, I suppose I should
go with the obvious. Meadowlarks are not larks.
They are actually in the same family (icterids)
as orioles and blackbirds.
I was thinking about those overheated black birds
of last week. One of the downsides of being
black is that you are going to get hotter in hot
weather than you would if you stuck to a lighter
color, especially if you are out in the sunlight.
We are in a sun drenched arid regime. It's hot
out there. You don't need to take in extra heat
to keep warm. Maybe a soaring bird like a raven
or a turkey vulture needs the black (actually
dark brown for the vulture) for loft but a crow
doesn't do a lot of soaring. So, why bother?
What's the point of being all black or having
black feathers or being like an indigo bunting,
where black feathers turn to blue in your view
because of light refraction effects?
As is
usual, the answer is many answers and ours begin
with eumelanin, a polymer that is also a pigment.
I mentioned heat absorption. Another reason you
might want to have some eumelanin around is that
you can develop part of your color palette from
it. Depending on concentration, you can get
various shades of dull grays to black. If you
put your eumelanin granules into ordered arrays,
you can develop iridescence. A third important
reason for investing in eumelanins is that you
can cluster your eumalanins in melanasomes and
strengthen a feather. This is likely why birds
that are mostly white, like white pelicans or
many gulls, often have wing tips or edgings of
black where feathers take the most stress.
Sounds good but I'm not done. Eumelanis, or the
dark brown phaeomelanins, are natural
anti-oxidants because they can suck up free
radicals and also bind heavy metals. They are
your first line of defense against heavy metal
poisoning. Not enough? Eumelanins are
antibacterial and antifungal. You are likely to
be a healthier bird if you use eumelanins. They
also transform UV radiation into heat optimized
to absorb around 340 nm (UV). The more melanin
you as a human have, the less likely you are to
develop UV related diseases like skin cancer. Of
course, every blessing is a curse. The more
melanin you have, the more likely a vitamin D
deficiency is.
I mentioned that eumelanins can act as traps for
copper and heavy metals. This fact actually gets
used in the paleontological study of fossil
feathers to discern where eumelanins were located
in the past. For example, based on copper
concentrations in fossil feathers, you can tell
that Confuciusornis sanctus, the earliest known
member of Ornithurae (lower Cretaceous, about
120-130 Myr), definitely had variably distributed
eumelanins and was probably a darkish "bird". In
case you are wondering, Archaeopteryx, is older
(circa 150 Myr) but more dinosaur than bird;
Confuciusornis is much more bird than dinosaur -
it has a true avian beak and, most importantly
from a classification perspective, a short tail
(not to be confused with tail feathers, which
were actually quite long in this species). So,
eumelanins were clearly viewed as a winner by
"birds" of the Cretaceous. They are still
winners today.
The date: 10/08/2012
The week number: 41
The walk number: 1164
The weather: 73 F, partly cloudy
The walkers: Alan Cummings, Kent Potter, Viveca
Sapin-Areeda, Carole Worra, John Beckett, Vicky
Brennan, Agnes Tong, Tom Palfrey
The birds (20):
Scrub Jay
Northern Mockingbird
House Finch
Anna's Hummingbird
American Crow
Mallard
Turkey Vulture
Western Meadowlark
Lesser Goldfinch
Red-tailed Hawk
House Wren
Common Raven
Yellow-rumped Warbler
Warbler, species
Hummingbird, Selasphorus
Bushtit
Black Phoebe
Band-tailed Pigeon
Yellow-chevroned Parakeet
Cooper's Hawk
--- John Beckett
Respectfully submitted,
Alan Cummings
10/15/12
http://birdwalks.caltech.edu/index.html
10/1/12
There are signs of heat stress everywhere in this
walk. Even before the beginning, I wander over
to the Throop ponds to check for a duck before
proceeding to the starting point of the walk, as
I do each week. I am absent luck today. There
is no mallard for me, although it is worth noting
that a drake appeared to be settling in later in
the week. He is newly molted post breeding (you
can tell because the breast is a solid bright
brown; if he has been fighting for females and/or
social position, you will see gouges where a
rival has snipped out a few feathers). Next week
may bring an official duck but, this week, I see
only a squirrel plastered over a branch. He
seems totally engrossed in finding cool thoughts
but they are elusive. He is so close that I
could touch him were I to lift a hand. He has a
sifting head and casts a baleful eye towards me
as he realizes that I am watching him. "Do I
have to get up and move higher? I surely don't
want to but he might be dangerous. Does he have
nuts for me? He might mean food." The slowly
churning cogitation never blooms into an action
as I turn away and migrate down to the starting
point for the walk. We begin with no birds.
A walk is like a little benediction. At the
beginning, we gather in a little cluster. Some
of us bring an offering to the list, the odd bird
seen on the way to the walk. Others bring
stories, just as important but not listable.
There are chickadees, lots of chickadees, in
Sierra Madre. The San Gabriel Mountains are full
of warblers. There were four western bluebirds
in my bird bath this morning. You never know.
This time, the stories are weak as we find
ourselves considering what is likely to be a hot
walk. Alan already has his collar up to protect
the back of his neck. By the time we get to the
back parking lot at the Health Center, which is
normally our first stop, Alan is already hopping
from shade to shade. There are two crows in
Tournament Park, mouths gaping into the hot air.
As we cross Michigan Avenue near the ticket
office, Alan notices that the sprinklers are
running. He walks right into the middle of the
spray, lifting his binoculars above his head and,
like an overheated supplicant, he is soon soaked
to the waist. In the meantime, Viveca and I
check out an acorn woodpecker in the shade side
of a palm tree and, fittingly her beak is open to
the sky. This is the down side of owning black
feathers. It's very hot, even in the shade.
Alan, who had dismissed the acorn woodpecker with
a glance, joins us on the sidewalk, only partly
satisfied with his swamp cooler exercise. He
eventually admits that he should have dropped to
his knees and allowed a torso soak. Viveca and I
elect not to get wet but I agree with the birds.
It is hot. "How hot?" you ask. I tend to judge
how strenuous a walk is by how much water I
consume immediately after the walk. For me, it
was a one liter day, which is at the upper end of
my scale.
Ah yes. I suppose I should mention the results.
We did fairly well considering the conditions but
we tied for the second lowest week 40 species
total of all time (the low was an 8 bird walk set
in 2008). We were well below the median of 16
and the record high of 25 was but a distant
dream. Except for a handful of yellow-rumped
warblers who were actively foraging in Tournament
Park, probably because they had just landed after
a long migration and were seriously hungry, the
birds were generally sessile and stressed. For
myself, I would have to say that the yellow
rumped warblers were the birds of the day. They
may have come in with a whimpering in week 39 but,
in week 40, the yellow rumped warblers are now here
in force. The Fall is really here. I can feel
it through the heat and I know it like the abyss
of a cleansing mind. The heat is nothing but an
aberration swept away in every gleaning warbler
leap. The Fall is here.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
I got a stellar view of a Cooper's hawk complete
with a stark white rump patch, which you don't
usually see in a flat area like campus because
you tend not to get a good angle for it. She was
flying across the parking lot of the child care
center. On the merits, however, the bird of the
day belongs to Alan's robin, which he saw in the
back yard of Morrisroe. The migratory robins
are coming through, leading to a rising pulse of
sightings starting in week 40 and cresting in
week 43. Some of these birds will decide to
winter around campus and this will yield
sightings from now until week 20 or so of next
year. We should also be seeing ruby crowned
kinglets as they generally arrive within a week
of the yellow rumps and white crowned sparrows
are readily acquired in the foothills around town
already although they have been a scattered
capture for us on campus over the last few years.
Wilson's and yellow warblers will, however, be
high profile targets for the next two or three
weeks. You have to catch them fast as they will
not be sticking around. I hope for cool. After
today's walk, I am ready for cool. I am ready
for the Fall. I am beyond ready.
I forgot to mention my favorite white breasted
nuthatch factoid last week and, given that it
might be another decade or a week before we see
another one, I thought I would just blurt it out
now, rather than talk about robins. It is a
matter of beetle juice and not a matter of
Burton. Nuthatches will rub beetle juice all
around the area of their nesting holes, both
outside and inside the hole but especially
outside. Sometimes, they accomplish this by
taking a beetle and rubbing with it until there
is nothing left. Sometimes, they slice open the
beetle and then dip a beak into the vessel to put
a layer of beetle juice on the beak and then rub
a wetted beak onto the bark. This is most common
in areas where squirrels compete for
nesting/roosting holes or have a standard path up
the nuthatches chosen nesting tree. It must act
as a squirrel deterrent at some level, perhaps
depending on the species of beetle and how
sensitive little squirrely feet and nostrils are
to it, and I have to admit that I'm tempted to
try it at home, where several squirrels are
resident, just to see what a squirrel does when
confronted by a tree smeared in beetle juice.
This sounds like a project for a ten year old.
I'm ready.
The date: 10/01/2012
The week number: 40
The walk number: 1163
The weather: 103 F, sunny
The walkers: Alan Cummings, John Beckett, Viveca Sapin-Areeda
The birds (11):
Rock Dove
House Finch
Anna's Hummingbird
Acorn Woodpecker
American Crow
Lesser Goldfinch
Black Phoebe
Yellow rumped Warbler
Hummingbird, Selasphorus
American Robin
Cooper's Hawk
--- John Beckett
Respectfully submitted,
Alan Cummings
10/9/12
http://birdwalks.caltech.edu/index.html