4/30/12
Each day, we are a river. Sometimes, the stream
is lost in a palmeted echo, finding passage only
in a memory, only as a touch. A mother nervously
tussles a child's hair in a waiting room.
Decades later, she has forgotten the waiting
room, the sick feeling of death lurking through a
terrible time, but she remembers the cool hair
flowing like a whispered prayer over her hand.
Each day we are a river, we are the flotsam of
others and, in the heart of our own soul, dries a
revealing sun. There is the birth of a child.
There is a first kiss. There is a first casket,
open to a great uncle who should be cracking
jokes but, instead, whispers from behind
"everything is going to be ok". There are the
lesser jewels. Each day, they are a river and we
dip into them, drawing at will, the unfaceted
song of a young house wren, or the dreamy
contemplation of a celadon vase and a bunch of
wildly bending tulips. I call to a house finch
and find myself calling to twenty house finches.
I see a mitred parakeet for the first time and I
remember the palm tree and the light and the
shredded red of the pair of birds. Each day they
are a river, I can choose, and as long as the
river listens, I can be chosen.
Do we know what we are going to see on a given
walk? Certainly, we have a rough idea of the
species most likely to be seen and who is likely
to be gone for the season but there are always
uncertainties and often surprises. This week is
an excellent example. We expected not to see any
more yellow-rumped warblers and I suppose you
could say that we were not "disappointed" by
their absence but we did see a Nuttall's
woodpecker pop into the nesting hole we
discovered last week. These were expected, or at
least anticipated events and nonevents. On the
other hand, we also encountered a red-lored
parrot, a species completely new to the Caltech
bird walk, and a yellow warbler, which is a
species we observe only every other year or so.
Overall, we encountered 25 species of birds, a
new record for week 18, topped off with that
red-lored parrot, in essence, a one in a thousand
walk bird. We advanced the record for week 18 by
two birds from the old maximum of 23, and we went
well beyond the median of 17 and the low of 13.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
Before this year, you have to go back to 2009 for
a new species (rock wren and lark sparrow) and
you might reasonably think that we had pretty
much covered all the species that we were going
to except for the odd vagrant. Just when you
think that we have a mature list of bird species
for the Caltech bird walk, however, we encounter
something new. Earlier this year, we picked up
chipping sparrows for the first time and this
week it was something quite different. We are in
the Maintenance yard when Alan notices a parrot
perched quietly in a small tree. At first, he
(and we) thinks that we are dealing with a
red-crowned parrot, but this bird has bright
yellow cheeks, making a red-crowned parrot
implausible (as was the sharp white eye ring) but
the red-crown is also well developed, completely
inconsistent with a yellow-headed parrot. Well,
we had just exhausted the entire collection of
parrots on the Caltech bird list and were quickly
exhausting the patience of the bird. Unless we
had a hybrid, we were dealing with something new.
Out pops the Sibley guide. Now, Sibley has a
limited collection of parrots but the red-lored
parrot looked like a good fit except that there
was no blue visible on the nape, as shown in
Sibley. This didn't kill red-lored parrot as a
possibility as Sibley also shows blue napes on
red-crowned parrots and you almost never see
them. We continue to try for more field markings
but the parrot's annoyance finally reaches
critical mass and he flies off, never having
provided any vocalization. Alan leaves the
listing, temporarily, as "Parrot, Species"
pending further research. After the walk, Vicky
pulls up the California Parrot Project, at
http://www.californiaparrotproject.org/
, and our
bird is a dead ringer for a red-lored parrot.
She also determines via e-bird,
http://ebird.org/content/ebird/, that there have
been at least a few reports of this species in
our area. You have to be careful with e-bird
because anybody can toss out a list but it's a
great place to get general trends and to assess
the potential for rare birds. The basic
conclusion from e-bird is that seeing a red-lored
parrot would be a rare but not implausible
sighting for our neighborhood. Later, I went
through Forshaw's book, "Parrots of the World",
and came to the same conclusion Vicky had
reached. Only a red-lored parrot made any sense
based on every line of evidence. So, we
officially have a 122nd species for the Caltech
bird walk. Our bird is likely an escapee or the
progeny of an escapee, whose forbears came from
the Caribbean side of southern Mexico or Central
America (our bird is a member of the subspecies
autumnalis). Red-lored parrots are a threatened
species due to habitat loss and, most especially,
to heavy depredations for the pet trade.
A second highlight came at the end of the walk.
While trying to coax out a common yellowthroat
near the Throop ponds, which was successful, we
noticed a yellow-colored warbler 40 feet up in
the Jacaranda canopy, at least the bottom of the
bird was all yellow and the bird was clearly a
warbler. Now, identifying warblers from the
bottom is not always easy but the bright solid
yellow quickly got us to a female yellow warbler
or a Wilson's warbler. The bird eventually
yields enough of a side view to show no hints of
a cap or strong auricular streak but it had light
colored edging on the wing. We had a yellow
warbler.
Yellow warblers are an uncommon sighting for the
Caltech bird walk. Since 1988, we have seen them
on just 22 occasions spread over 15 of the last
24 years. These mostly occur in a big pulse in
the over weeks 17-21 associated with the Spring
migration and then, in much smaller numbers,
returning south in August and September (weeks
32-41). Since our bird was a female and males
usually migrate first about a week before the
females, we have probably missed out on any more
yellow warblers from this particular batch of
migrators. We still have a shot at another of
these birds arriving from a different wintering
area over the next week or two. Perhaps, we
should anticipate it.
The date: 4/30/2012
The week number: 18
The walk number: 1141
The weather: 70°F, sunny
The walkers: Alan Cummings, Viveca Sapin-Areeda,
Carole Worra, Vicky Brennan, Ashish Mahabal, John
Beckett
The birds (25):
Scrub Jay
Northern Mockingbird
House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
European Starling
Lesser Goldfinch
Mallard
Spotted Towhee
Red-lored Parrot
Band-tailed Pigeon
Red-whiskered Bulbul
Black Phoebe
White-throated Swift
House Wren
Nuttall's Woodpecker
Bushtit
Cooper's Hawk
Black-chinned Hummingbird
Yellow chevroned Parakeet
Common Raven
Common Yellowthroat
Yellow Warbler
--- John Beckett
Respectfully submitted,
Alan Cummings
5/4/12
http://birdwalks.caltech.edu/index.html
4/23/12
It was a cool walk rich in highlights. We saw
two laggard yellow-rumped warblers outside
Tournament Park. At week 17, they brought us
into a tie with last year for the latest Spring
sighting of this species. We also located the
nesting hole for our local Nuttall's woodpeckers,
we saw a pair of black-headed grosbeaks, a rare
sighting on the walk, and we were treated to the
courtship dance of a western bluebird. We also
did quite well by the numbers. We encountered 26
species. This is not a record, which was and
still is 29 (set in 2010 and tied last year), but
we were well above the median (18) and low (12)
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
A quick look at Alan's general species versus
time plot shows that the number of species
decline as the broad pulse of the Spring
migration lifts like a wave beneath us and then
relaxes towards those birds that have decided to
breed in our area. We have been picking up
red-shouldered hawks with some regularity,
although we have yet to locate this year's nest
(curse those winds for destroying last year's
nest!). However, we do now have a readily
visible nest location for a Nuttall's woodpecker,
which is visible from the driveway leading to
Tournament Park from Wilson. Alan first picked
it up when he saw the female pop into the hole.
The male followed her in a couple minutes later.
The male Nuttall's makes multiple potential
nesting holes and it is the female who decides
which, if any, to use. We may have just seen the
consummation of that process. Vicky recorded the
black-chinned hummingbird. These birds are
passing through now. If we are lucky, one of
them will decide to nest at Caltech, as happened
in 2007-2008 (ten sightings in each of those
years). It is generally males first during the
Spring, one of which we encountered this week,
followed about a week later by the females (so,
keep your hummer eyes open on the next couple of
walks). In the Fall, the black-chinned
hummingbird migration is much more spread out
because the females and, especially, the
juveniles, take their time moving south.
We hit a highlight very quickly. In the
Maintenance yard, we had been seeing and hearing
house finches but Hannah picks up a more unusual
pair of birds in a eucalyptus. One is a
brilliantly decorated male black-headed grosbeak.
The other, more demure in the sense of generally
having some interfering foliage, nevertheless
revealed a much lighter colored breast, an
accompanying female. This is the eighth sighting
of this species on the bird walk, all but one (a
week 31) in the Spring, five of the seven from
week 17, and one of three encounters over the
last three years. This is a good trend but it is
built from a small number base and, given the
highly restricted occurrences, we can only hope
that these birds are part of a more grosbeaky
future.
Black-headed grosbeaks don't seem to be a popular
subject of study but they are certainly worthy of
it, quite apart from their songs (think robin on
steroids). They are one of the few species to
have figured out how to eat Monarch butterflies
without dying of a cardenolide-overdose (if you
make a mistake in this game, you will soon find
your heart, lungs, and kidneys hemorrhaging, so
this is not something you want to mess around
with just for fun). The trick is to only work
with the abdomen and head and to reject the third
or so of Monarchs that are too toxic to use.
It's likely that depredations by black-headed
grosbeaks are a good part of the reason that
Monarchs tend to winter in dense colonies (losses
to avian predation are inversely proportional to
colony size). I mentioned singing above. One
unusual feature of black-headed grosbeaks is that
both the male and female sing. Generally, the
female songs are structurally simpler but this is
not because the males are better at it. Now and
then, a female sitting on a nest will belt out a
good representation of a male's song. Her mate
hears this and immediately flies back from
wherever he's been hanging out, ready to blast
the intruder, but he finds no intruding male. The
interloper must have left in a hurry but, having
found no threat to his territory, our intrepid
male soon finds himself incubating eggs (both
sexes have what amounts to a brood patch) and our
happy hungry female wanders off to forage for
herself.
The common yellowthroat is always a pleasure,
usually brief but the big late highlight came as
our eyes lift above the recycling plant. We come
to a eucalyptus, limbs hacked into truncated
spires by fear of a great wind. Initially, my
thoughts are of lost potential but then I see the
dancing floor. Above me she, a following sea, is
the song I sing to her beauty that brings a dance
with a grackle tail and stiffened wings. They
are my heart and she knows the stillness around
my voice, stretching to the distal blue of
progeny. She can see them in my song and in a
lacy looping dance we carried from the Nuttall's
roosting hole. She is in a limpid sky holding
only the pedestal her and, in a shallow twisting
turn, tail up, she chooses. She chooses me.
The date: 4/23/2012
The week number: 17
The walk number: 1140
The weather: 58°F, cloudy
The walkers: Alan Cummings, John Beckett, Viveca
Sapin-Areeda, Hannah Dvorak-Carbone, Kent Potter,
Vicky Brennan
The birds (26):
Northern Mockingbird
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
Mallard
European Starling
Lesser Goldfinch
Common Raven
Yellow chevroned Parakeet
Spotted Towhee
Red-Whiskered Bulbul
Black-headed Grosbeak
Nuttall's Woodpecker
Black-chinned Hummingbird
White-throated Swift
Yellow-rumped Warbler
House Wren
Black Phoebe
Red-shouldered Hawk
Bushtit
Band-tailed Pigeon
Western Bluebird
Hummingbird, Selasphorus
Parrot, species
Common Yellowthroat
--- John Beckett
Respectfully submitted,
Alan Cummings
4/27/12
http://birdwalks.caltech.edu/index.html
4/16/12
There are many themes in a walk. They express
themselves in a few numbers, a few steps, in a
casual conversation. They may bridge a lacunal
pattern of thought that passes from week to week,
bearing the children of a memory or a season. We
see one every time we open our eyes and sing to
the altering sky. It can pass in the momentary
glance of a distant bird to the intricate dance
of a barbicel. This time, we were left with a
record-tying day for week 16. We had 25 species,
matching the total 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
Week 16 tends to be a week of clasping
transitions, perhaps most clearly seen in
yellow-rump warblers because they are common
around the campus one week and then seem to
evaporate. There are two varieties of this
species, both with well defined yellow ovals on
their rumps (hence the name) and yellow streaks
on their flanks. Most of our wintering
yellow-rumps are Myrtle's with some female
Audubons. The Myrtles have whitish to buff
colored throat patches and are relatively light
colored with fairly prominent auriculars (cheek
area behind the eyes). Audubon's have decidedly
yellow throats, weak auriculars, and the males in
Spring plumage can be quite dark. So, when you
have been seeing mostly Myrtles for several
months and you are suddenly seeing a lot of
mostly male Audubons in very bright dark breeding
plumage, it can be a bit startling. My take is
that our winter residents (mostly Myrtles) have
all left town and we were seeing a small
collection of more southerly wintering Audubons
passing through campus as they also migrate north
for the breeding season. We have likely just
been treated to our last flamboyant view of a
yellow-rump for the season. There is hope for
next week but the only time we have picked up a
yellow-rumped warbler as late as week 17 was last
year.
It's hard to say what is going on with Caltech's
mountain chickadees beyond the dramatic increase
in sightings. Historically, they have been a
once every few years kind of bird for us but last
year, we had as many sightings as all other years
combined and this year is looking to be
chickadee-rich as well. This week, Alan caught
one moving nesting material near the Maintenance
yard (they are secondary hole nesters but do add
lining material to their nesting cavity) and this
suggests that we may actually have a breeding
pair on or near campus. I had originally thought
that a massive influx of mountain chickadees was
a Station fire (2009) effect that would have
dissipated by now but, apparently, some of these
birds must like us.
Sometimes, it is an ambiguity that bears
identification. Viveca spots a soaring bird and
Melanie soon spots it, too. I never get a glass
on the bird in spite of an assortment of waving
arms and helpful hints, so I am left to kibbitz
from the side as the two of them try to come to
terms with field markings on a distant bird.
They get to a long thin tail and lots of red.
Now, the tail effectively eliminates a
red-shouldered hawk, which can have a fair amount
of red and the red disposes of accipiters like
sharp-shinned and Cooper's hawks. We were left
with an American kestrel. It was not a great
view but we'll take it as the last kestrel
sighting on the walk was in 2009 and we've only
had two previous sightings in the last decade.
The kestrel reminds me that I am sloppy about
appellation at times. I tend to think of an
arbitrary soaring bird as an arbitrary "soaring
bird" or "soarer". Having dismissed vultures,
crows and ravens, I get to "hawk". I am at this
point, including falcons in the catchall even
though I know this to be intellectually sloppy
and that raptor would be the better term. Raptors
include both falcons and hawks but falcons, like
kestrels, are not hawks. However, I've just
never been able to bond with the word "raptor",
except on contemplation and I am, therefore, left
with a bad habit and the error of my ways.
Falcons have a special notched bill that hawks
lack and this adaptation allows them to
efficiently slice through the notochord of their
prey, thereby paralyzing them so that they can be
eaten in peace. Presumably, this is a
consequence of prey sometimes being large enough
to seriously threaten the captor. It's a
gruesome world out there.
Like many hawks, American kestrels are sexually
dimorphic in size (males average about 10%
smaller than females) but it is the plumage
differences that are most striking (I leave you
to google some photos to convince yourself of
that). Smaller males tend to be more
maneuverable and better hunters. In choosing a
mate, the female looks for size (smaller is
better) and plumage brightness and condition,
which allow her to gauge body condition and age.
The size differential between the sexes is
obvious by day six after hatching but this
apparently doesn't lead to significant
disparities in sex ratios among fledglings in
normal years. If you are a male nestling, your
sister may be able to grab that vole but she
can't simultaneously hold it, defend it and eat
it. You get your fair share. In a bad year,
your sister is actually at a significant
competitive disadvantage because she can't
monopolize most of the prey but she does require
more calories to fledge successfully. As a
tidbit, I note that male kestrel eggs are
actually bigger than female eggs, so if the
female felt like manipulating sex ratios in the
brood, she could. Apparently she doesn't, at
least not after laying the eggs. Our bird was
likely a male who already has a mate if he is
going to get one this year (January-February is
for courtship; by April/May, the female has
chosen a nest hole and there is a decent chance
that she is already incubating eggs. It may be a
busy neighborhood because there are not an
infinite number of suitable nesting sites. A
couple of years ago, I saw a palm tree down at
Bolsa Chica that had nesting great blue herons
and great horned owls on top and hole nesting
western bluebirds and American kestrels in the
trunk. It was a pretty raucous collection. It
is generally thought that kestrels have come to
the cavity game fairly recently because they
still have speckled eggs. Most cavity nesters
have white or at least solid color (blue for
western bluebirds) eggs. For the baby kestrels,
it will be a one month incubation, five weeks to
fledge and another two to four weeks of on the
job training, after which you get to starve on
your own although juveniles sometimes form
hunting clubs. Life is a lot of work and then,
of course, you die.
The date: 4/16/2012
The week number: 16
The walk number: 1139
The weather: 77°F, sunny
The walkers: Alan Cummings, Viveca Sapin-Areeda,
Vicky Brennan, John Beckett, Melanie Channon
The birds (25):
Scrub Jay
Northern Mockingbird
House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
White-throated Swift
European Starling
Yellow-rumped Warbler
Mallard
Red-shouldered Hawk
Woodpecker, Species
Lesser Goldfinch
Black Phoebe
Mountain Chickadee
Bushtit
Common Raven
Bewick's Wren
Yellow-chevroned Parakeet
Band-tailed Pigeon
Red-tailed Hawk
Turkey Vulture
American Kestrel
Common Yellowthroat
--- John Beckett
Respectfully submitted,
Alan Cummings
4/20/12
http://birdwalks.caltech.edu/index.html
4/9/12 4/2/12
It was a nice walk. That about sums it up. We
met our 131st walker of the Caltech bird walk,
Jason Price, and we had a very busy raptor day.
The ravens are now actively nesting on
Parsons-Gates. Alan first put down raven based
solely on a big black lobate tail extending above
one of the nests (what else could it be?) but
Viveca also picked up another of her black specks
in the sky as we rounded Millikan at the end of
the walk, which firmed the allocation. The
red-shouldered hawks are thinking about nesting,
if they haven't already picked out a spot. They
were engaging in courtship spirals but we didn't
see any of the courtship dives that the male
tends to throw into the mix and Darren claimed
that one of them was in juvenile plumage, which
would not bode well for any future offspring.
Juvenile males rarely mate; but juvenile females
sometimes pick up an older male, although these
liaisons often lead to infertile eggs and
generally don't lead to any fledging hawks. We
also saw three turkey vultures over the
maintenance yard and picked up an accipiter (the
hawk species listed below). It was a likely
Cooper's but the look wasn't good or long enough
to be sure. Since we intersected a drilling rig
crew getting ready to take soil samples, it looks
like the maintenance yard is physically starting
to go down the child care track and this will
lead to some imponderable impacts on the walk
over the next year or two.
Over all, we did reasonably well by the numbers,
especially considering the extremely active
skies. We encountered 22 species, well below the
record 29 for week 15 but still above the low
(14) and median (17).
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
I do admit to a disappointment. It came near the end of the
walk, where we didn't see or hear any common
yellowthroats. This may be bad luck, our birds
wising up to Alan's app or, on the dark side of
the spectrum, our pair eloping from Caltech and
moving to a buggier home.
The bird of the week has to be the red-shouldered
hawk. We can probably expect only one pair in
our area (territories in southern California are
usually around 100-120 acres, about the size of
the Caltech campus) and, last year we had an
active nest south of but in easy view of the
driveway leading from Wilson to Tournament Park.
It contributed several sightings to the 18 we
picked up last year (the previous record for
red-shouldered hawk sightings in one year had
been five). This year's nest site may not have
been determined yet, but we are all hoping it
will be in a line of sight that we can take
advantage of. Red-shouldered hawks are an
example of one or two individuals having a huge
impact on the sightings frequency for a species.
We already have five sightings of red-shouldered
hawk sightings in 2012, which is comparable to
our pace for last year and consistent with a pair
of hawks maintaining a territory that includes
Caltech. To give you a sense for how unusual
this is, we only reported a red-shouldered hawk
sighting about once every three years between
1995 and 2005. These were probably rovers who
don't have a fixed territory or, perhaps, the odd
migrator coming up from Mexico.
Being in an active red-shouldered hawk territory
yields opportunities for seeing red-shouldered
hawks but it likely also leads to some
suppression of activity in small birds that we
might otherwise pick up. The lord giveth and the
lord taketh away. Since red-shouldered hawks
hunt almost exclusively from perch, looking for
small reptiles, mammals, and birds (they also
have a sincere fondness for frogs and they are
not above eating carrion), we are most likely to
pick them up when they are on a nest (all
incubation is female), on a courtship flight,
defending territory against other hawks, or
calling as they fly from one perch to the next.
During the winter and Spring, these birds are
very talkative so if there is one hanging around
nearby, you are likely to know about it.
Finally, I would like to say a few words about
domestic cats. I had a cat in my crib when I was
a baby and there is a fair chance that I actually
thought I was a cat when I was young. They have
always been a natural part of my environment and,
when not present, I know not so much the
intuitive absence of a pleasure but more an
intuitive emptiness. It fills only in a gliding
hand and a receptive cat. I love cats. Over the
years, I have met and known many, mostly
outdoors. Each brings a fulfilling grace and in
the moments of our interactions we live within an
ethereal pattern. It is a matter both
inarticulate and completely sensual. We move
within the moment but we are not merely in the
moment. We are the moment.
It is fortunate for me that I have met so many
cats but it would have been better for the world
if I had not. They are all natural born killers,
especially when young, and they are one of the
biggest anthropogenically induced source of bird
mortality in the country. For some species, cats
account for the bulk of fledgling mortality in
urban and suburban areas. Locally, they are a
horror show for hermit thrushes. A lot of
arbitrarily inflatable numbers get thrown around
about just how many birds cats kill in this
country but something around a hundred million
birds a year seems to be plausibly supported
(about half feral and half pets). That's in the
same ball park as the toll wreaked by power lines
and more than automobile strikes, pesticides,
radio and television towers, airplanes, wind
turbines, fishing nets, or oil spills. Only
buildings, mostly in the form of windows, are a
substantially greater threat. "Well!" you
respond. "I am just allowing my cat an
opportunity to be natural." No, you are not.
You feed your cat. We feed all of our cats,
whether feral or pet, whether directly or
indirectly, and this leads to densities of cats
that are orders of magnitude higher than can be
supported by the wildlife passing through. This
is unnatural. It is a great maw of teeth and
claws gaping wide in sport for fledgling and
ground foraging adult birds. We are dealing death
for lizards and snakes and it is an unnatural
evil because it is not aligned with any natural
balance caused by the number of cats that could
actually live off the land. It's not
particularly good for your cat either. She will
have a shorter life and more disease and injuries
if she goes outside. That doesn't mean that you
should be shutting her up in some dark windowless
room. Your cat needs stimulation and
interaction. Your cat needs cat TV. She needs
an open window to take in the sights, smells,
and sounds of the outdoors. Your cat will have
favorite games. Play them. If you want to,
bring in wild prey. She will be ecstatic if you
bring in a grasshopper or a flight worthy katydid
for her to chase (you will want to keep an eye on
the proceedings or accept that you will be
running into the odd body in the odd place at the
odd (and probably socially undesirable) time. Is
this unnatural? That insect was eating your
roses and you were going to kill it anyways (that
lizard, on the other hand, is beneficial for
your garden. He would like to be eating crickets
and katydids and not be killed and then discarded
by some pampered predator). That fledgling bird,
on the other hand, will be breeding next year
because your cat didn't kill him.
Are you determined to let her out? Ok. I
certainly can't stop you, although the
neighborhood coyote eventually might (my
immediate neighbors on all three sides of my
property have lost a cat to a coyote in the last
decade and we have regularly touring coyotes,
both day and night, assiduously looking for cats
and squirrels). Think about keeping your cat
inside until she is two, or at least one.
Younger cats, in the few month to two year range
account for a disproportionate fraction of
cat-based avian predation. Bell your cat. This
can drop bird predation by a factor of two
although it won't do a thing for your local
lizards. Tell her that she is not allowed to sit
near the birdbath or bird feeder. All cats have
a keen grasp of boundaries and it is not
difficult to impose an avian safety rule on her.
If it is not obvious how one should go about
establishing such a boundary, read about how to
train cats in a standard cat book or on line.
Do it properly and your cat will know to the inch
how close she is allowed to be to that bird bath.
She will spend a lot of time thinking about how
to intercept a bird coming into or flying out of
the birdbath and a good jumper will still manage
to kill some birds en route but, overall, the
kill rate will decline because she will respect
the boundary. You can also try to supervise the
outdoor visitations. You will be able to save
the odd fledgling and adult bird simply because
your presence will be noted and, therefore, your
cat will have fewer opportunities to kill one.
There are many reasons why birds in general and
certain species of birds in particular are in
serious danger of going extinct. The pet bird
industry is one stressor on population. Pet bird
killers killing birds is another. Felis catus
can be a wonderful companion but she should not
be allowed outdoors.
The date: 4/9/2012
The week number: 15
The walk number: 1138
The weather: 78°F, sunny
The walkers: Alan Cummings, John Beckett, Darren
Dowell, Viveca Sapin-Areeda, Vicky Brennan, Kent
Potter, Jason Price
The birds (22):
Northern Mockingbird
House Sparrow
House Finch
Anna's Hummingbird
American Crow
European Starling
Lesser Goldfinch
Mallard
Turkey Vulture
White-throated Swift
Hawk, species
Red-whiskered Bulbul
Yellow-rumped Warbler
House Wren
Red-shouldered Hawk
Bushtit
Red-tailed Hawk
Black Phoebe
Hummingbird, Selasphorus
Yellow-chevroned Parakeet
Band-tailed Pigeon
Common Raven
--- John Beckett
Respectfully submitted,
Alan Cummings
4/16/12
http://birdwalks.caltech.edu/index.html
Ah!! There is nothing quite like the sweet smell
of a new record. It twines upon the sensing mind
and, somehow, in a single mare breath, distills
the passing pleasure of a historically great
walk. It certainly makes for an easy write-up.
This week, however, we failed to have such a
simple conjugation of our time. We played in a
subtle key but it was a day of sweet songs. The
record for week 14 is 29, which was set in 2007.
We didn't get there. Our total was 22 species,
providing no contest for the record, but the
median is only 18 and the minimum 10. So, even
from a crude number of species game, this
qualifies as a solidly respectable showing. From
a pleasant experience perspective, it had a lot
going for it.
See the plots at
http://birdwalks.caltech.edu/bird_data/species_time.html
and
http://birdwalks.caltech.edu/bird_data/two_plots.htm
April is a time of transition in avian world of
southern California. We had a house wren
advertizing the low hole in the gum tree in
Tournament Park. He popped into the hole,
presumably to make sure that it was as spiffy and
attractive as possible and he then popped out,
flew over to the fence a few feet from Viveca and
Vicky, turned to face them and poured out the
verbal liquid of his heart like water flowing
into a desert sand. With a crooner like that, I
expect babies, lots of babies. He and another
house wren, who was singing from further away,
will likely be with us for the next couple of
months, assuming they are able to attract mates
into their stellar nesting holes. Perhaps, they
have already succeeded as house wrens are
tireless singers throughout the Spring. We also
saw white-throated swifts; they breed in our area
and are semi-reliable Spring-Summer captures for
us. This is the context of breeding birds at
Caltech. Renewal is upon us and absence is the
renewal for others. Most of our standard
wintering and migrating warblers have already
left, although this has been a rather poor
warbler winter for us, so it's actually a little
hard to tell. In another possible sign of
absence, we saw a ruby-crowned kinglet last week
but, this week, there were none. Since the last
kinglet sighting of the winter tends to be around
week 14, we may have seen the last of our
kinglets, too. We are still seeing yellow-rumped
warblers but they will also be leaving soon. If
we are lucky enough to pick up a yellow warbler
later this month, that will probably be the end
of the warbler show unless another Channel Island
orange crowned warbler decides to take up a
summer residence near Caltech.
There were a number of highlights to blend with the non-lights.
I mentioned the house wren above. I must also
mention the common yellowthroat. Last week, we
saw a male in full breeding plumage out in the
open near Throop pond. This week, a more subdued
version of a common yellowthroat flushes from
bushes east of the lower Throop pond and flies
over to the Indian hawthorns lining Thomas. I
had a view from the side and I thought I saw
yellow in the throat area, which would make this
an adult female (the first year birds don't have
the yellow throat patch), but maybe I was engaged
in wishful thinking and managed to transform the
yellow side wash common to all common
yellowthroats, into a throat patch, yielding
second year female. If this was an adult, it
suggests that our common yellowthroat male has
attracted a mate and that we may, therefore, be
treated to an extended Throopy family of common
yellowthroats. That would be seriously cool.
Another highlight was the sighting of two
white-crowned sparrows in Tournament Park. We
have collected three white-crowned sparrow
sightings so far this year. For us,
white-crowned sparrows are strictly wintering
visitors and week 14 is very typical for a last
Caltech winter sighting (it averages week
14.4±1.4 (one sigma) for those years in which we
had enough sightings to reasonably infer
departure). Our birds are off to Canada and
Alaska and we won't be seeing them again until
week 40 (early October) or later in the year, at
least, that's how I hope it plays out.
Broadly speaking, the word for white-crowned
sparrows at Caltech is "not good". There has
been a serious and generally persistent decline
in the number of sightings for this species that
extends all the way back to the origins of the
Caltech bird walk as it first began to take shape
in something resembling its modern religious once
a week form in 1988 (the walk began in 1986 but
1988 was the first full year). On average, the
number of white-crowned sparrow sightings has
declined by about 3/4 of a sighting per year
(about 4.4% a year), dropping to zero in 2008 and
2010. This, in spite of the average number of
birders tripling over the same time period (i.e.,
as you increase the number of birders, you become
somewhat more likely to see/hear at least one of
a given number of available birds; more birders
seeing fewer birds is likely to mean that there
are a lot fewer birds of that species to be
seen). Sightings in the last couple of years (4
in 2011 and 3 so far this year) suggest a
possible uptick but we are now dealing with small
sporadic numbers. This is not good, at least not
if you like white-crowned sparrows.
So what has happened to the white-crowned
sparrows of Caltech? I can't tell you, although
there has been a broad regional decline in the
species (numbers are increasing in the Midwest).
I can, however, offer a couple of possible
correlative clues for our local observations.
Between 1988 and 1999, numbers of house sparrow
sightings and white-crowned sparrow sightings are
linearly correlated (r squared = 0.78). Both
species were in rapid decline, even though one of
them (house sparrow) is a year round resident and
the other only winters here. If we had a good
year for house sparrows, we had a good year for
white-crowned sparrows and a bad year for one
meant a bad year for the other. In contrast,
house finch sightings have increased steadily
since 1998. Perhaps, local concentrations of
small seed supplies of the type preferred by
sparrows declined during this time, making
Caltech and environs less appealing to a
white-crowned or house sparrow regardless of when
the cuisine was being tested. If a migrating
white-crowned sparrow found Caltech unappealing,
he would just keep going. If a resident house
sparrow ran into the same problem, he would leave
or starve. The net result has been fewer sparrows
harnessed to a broader regional decline.
In this millenium, there has been no correlation
between numbers of house and white-crowned
sparrow sightings. House sparrows sightings
rose between 2000 and 2004, even as white-crowned
sparrow sightings continued to decline. This
would suggest a regional imprint for the
white-crowned sparrows but, after peaking in
2004, house sparrow sightings have gone into
decline again. We now seem to have a small but
fairly persistent, if not robust, flock on
Wilson, so sighting probabilities may improve,
but this is the thin reed of a vulnerable
population. As a point of contrast, house finch
sightings have been increasing steadily since
1998. House finches can handle larger seeds and
larger distances between concentrated food
sources, a significant advantage over the more
sessile sparrows when times are tough. On the
whole, Caltech appears to have become a finch
country.
The date: 4/2/2012
The week number: 14
The walk number: 1137
The weather: 75°F, partly cloudy
The walkers: Alan Cummings, John Beckett, Viveca Sapin-Areeda, Vicky Brennan
The birds (22):
Northern Mockingbird
House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
White-throated Swift
Yellow-rumped Warbler
Mallard
Bushtit
Red-whiskered Bulbul
Red-shouldered Hawk
Red-tailed Hawk
White-crowned Sparrow
Woodpecker, species
House Wren
Common Raven
Lesser Goldfinch
Cedar Waxwing
Black Phoebe
Hummingbird, Selasphorus
Common Yellowthroat
--- John Beckett
Respectfully submitted,
Alan Cummings
4/6/12
http://birdwalks.caltech.edu/index.html