bird data > past walk reports

2/28/12

By the numbers, this was a solid but unspectacular walk. We got 22 species, just above the median for week 9 of 21.

See the plots at http://birdwalks.caltech.edu/bird_data/species_time.html and http://birdwalks.caltech.edu/bird_data/two_plots.htm

Highlights were, however, abundant. Melanie got not one but three new lifers (Cooper's hawk, yellow-chevroned parakeet, and common yellowthroat). Now, I can hear you Audubon types snickering like a Greek chorus in the background, saying that a yellow- chevroned parakeet is not an official U.S. bird because the species hasn't expanded territory sufficiently or built enough numbers but I say to you, "Be quiet!" Lists are whatever the individual birder wants to make of them. Melanie has now seen a yellow-chevroned parakeet in the wild. It's on her life list. Get used to it.

Our first highlight came in the Maintenance yard as a red-tailed hawk flew by, just over my head level and not more than ten meters away from me, rising and then landing in full view on a telephone pole, where it perched and studiously ignored us. After a few minutes checking the grounds for squirrels and other rodents, it flew over to an abandoned nest on the other side of the yard, tramped around and, after mulling things over for another couple of minutes, flew off. Our visceral response was that this was a bird looking to nest. It is the right time of year for red- tails to be setting up housekeeping (they are generally monogamous, often mate for life, and will be laying eggs in a couple of weeks) but this was an immature bird (brownish tail with bands) and it was alone. Red-tails don't develop the red tail feathers characteristic of the adults until their second year and they usually don't start breeding until their third year (most of them never get to that point). Also, unlike Nuttall's woodpeckers, choosing and decorating a nest tends to be communal (actually, they generally build or spruce up more than one nest, then choose one for incubation). There are precocious exceptions, no doubt, but I suspect that our hawk was actually considering the nest as a possible hunting perch rather than as a potential nursery. Red-tails prefer to hunt from perches rather than soaring for their supper, so scoping out quality low lying perches is a serious business for a young red-tail. Still, I could be wrong and we will certainly be keeping an eye on that nest. Like most hawks, red-tails are sexually dimorphic with males significantly smaller, by a quarter to a third, than the females. Given the basic design, smaller size in hawks generally translates into more maneuverability and, at least for hard to catch prey, better hunting skills. In a bad year, this can be the difference between fledging your young and not, so overall size definitely matters to a female red-tailed hawk and she selects for this trait. When a pair is together, you can often sex them by size but, alone, as in this case, I wouldn't even hazard a guess without a photo and a scale (it would have been textbook quality, Ashish).

Immature red-tailed hawks like ours try to stay out of the way of local resident adults for good reason. They tend to use relatively low perches and have mushy territories that they don't defend. As Viveca speculated, this may be the immature hawk we have seen on two or three occasions over the last couple of months flying around at low elevations across campus, sometimes accompanied by crows. This hawk may, therefore, be bonding with the campus and may, therefore, ultimately establish a territory that encompasses it (red-tailed hawk territories are typically a few square kilometers in area and I might add, it is generally the quality of the perches that defines the quality of the territory). Our red-tail hawk was an especially lucky bird for us because it actually brought us a second species. A mourning dove that was out of my line of sight, flushed as the hawk flew over and practically did an Immelmann trying to get out of the way. The hawk ignored the entire affair.

Tournament Park brought a classic Viveca pattern recognition discovery as she ferreted out an "anomaly" perched on a branch high up in the canopy. The bird was viewable only at a very bad, almost vertical angle and, although we quickly got to accipiter species based on the tail, we had a lot of trouble getting more specific. Alan was campaigning for "hawk species" and a departure when, finally, the bird leans over and we can see a charcoal cap with a sharp light break in color striking to the back of the head. Viveca's anomaly was a Cooper's hawk.

Beauty can intrude. To some, it seems the flower of a single strand of hair. It curls lazily across a lover's shoulder and you, for one moment, are in a poet's dream and you glow the room. Beauty can be an incandescence shared and it can be the subtle flotsam of found art that once bound, somehow, becomes accessible to many. Today, we had such an accessible moment. At the end of the walk, we came up to the Millikan ponds and trekked over to the bushes, hoping for a common yellowthroat sighting. Alan calls up his bird song app and slides his way to a common yellowthroat. We hear and see nothing except the lyrical call emanating from Alan's hand. The song ends and we, clumped in disappointment, turn away and walk up the steps leading out onto the coping surrounding the reflecting pool. At the lip, we turn back for a last sweeping glance over the ponds and notice a light colored bird flying rapidly from the Indian hawthorns across the walkway over to the bushes bounding the lower Millikan pond. Was this our bird? We drop back down and start scanning bushes. The bird pops out and flies across the first pond to bushes on the other side and then across the second pond into a George Tabor in full bloom. The Tabor is having the best bloom of its life at Caltech because the canopy, opened by the big wind of last year, has, finally, brought the sun to an azalea, which having drunk deeply, explodes in a profusion of spotted pinks. The common yellowthroat pauses for a few moments and then casually forages within the Tabor. He is now a magnificent adult male in full breeding plumage. My eyes had, only moments before, passed over this bush without tarrying for even an extra second but the contrast of the pink azalea blossoms with the yellow, green, brown, black and white of the warbler is sublime and the combination is a found art. I revel in the common yellowthroat but I am drinking the beauty of the Tabor.
The date: 2/28/2012
The week number: 9
The walk number: 1132
The weather: 56F, partly cloudy

The walkers: Alan Cummings, Vicky Brennan, John Beckett, Viveca Sapin-Areeda, Melanie Channon

The birds (22):

House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
Lesser Goldfinch
Yellow-rumped Warbler
European Starling
Mallard
Red-tailed Hawk
California Towhee
Ruby-crowned Kinglet
Cooper's Hawk
Hummingbird, Selasphorus
Common Raven
Bushtit
Downy Woodpecker
Black Phoebe
Band-tailed Pigeon
Yellow-chevroned Parakeet
Snowy Egret
Common Yellowthroat

-- John Beckett

Respectfully submitted,
Alan Cummings
3/2/12

http://birdwalks.caltech.edu/index.html






2/21/12

Respectability seems to have returned, although we took it to the nearly last possible moment to get there. Alan and I wander over to the dwarf pittosporums by the mallard's favorite pond and Alan plays an iPhone version of a common yellowthroat song. Now, breeding bird songs are often not very evocative for birds during the winter but some birds start to get territorial near the end of the winter season. Out of the corner of our eyes, we see a flashing bird, not enough for an id. I wasn't even sure of the color. Alan continues to play a common yellowthroat and our bird swoops over a rock in clear but very brief view and then proceeds, from a new safe haven, to chitter at the iPhone. We were marginally relevant, except as big clumsy predators preventing a confrontation. Our bird's opinion of Alan's plastic monstrosity was, however, not suitable for reproduction before a mixed audience but his annoyance brought us to 20 species for the day.

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 some highlights to the walk in addition to the common yellowthroat. Vicky and Viveca thought they had a towhee in the bushes by Morrisroe but the bird was quiet and no amount of enthusiastic phishing or peering could net a definitive look. The bird moves handily away from the hullabaloo and stays out of their view but this leads to a clear view for Alan. We had a spotted towhee. We also picked up another Say's phoebe at the baseball field, our third sighting of the year. The last Say's phoebe sighting of the winter is generally sometime in weeks six to nine (and never, at least so far, after week 10). So, I think I had better get the Say's in as a bird of the week before I lose the chance for several months. The Say's phoebe is one of those species where you will see summaries peppered by "presumably", "no data", "no specifics", "no information", "little information", "few data", "not known", "unknown", "poorly known", and, perhaps most pertinent, "needs study". So, I will take a different tack.

Alan's collection of bird species from the Caltech bird walk holds a trove of interesting tidbits, trends, and curiosities and, if you are careful with the inherent biases, you can say a lot about local avian populations as a function of year and season. There is some bias associated with the birders. For example, the number of turkey vulture sightings reported for the walk reflects, in no small part, the number of eyes available to scan the skies. There is also some bias associated with the specific individuals on the walk. For example, we tend to get an extra species or two if someone with especially good ears is with us. In contrast, I probably don't add a lot of species but I gain some comfort from the idea that every hero needs a chronicler. The bias is, however, not all about the birders. A simple listing by species does not distinguish between one bird and a hundred. If a bird decides to winter at Caltech or breed in the Spring at Caltech, you may get a dozen sightings while that bird is here. If that same bird decides to move along a few hundred meters or a few hundred kilometers, you may see the bird once or not at all. Black-chinned hummingbirds are a good example. Typically, we get two or three sightings a year as these birds pass through Pasadena on their Spring and Fall migrations but they do occasionally breed in the San Gabriel Valley and, in 2007 and 2008, we had ten sightings each year, almost certainly associated with one of these birds deciding to breed somewhere in or near the Maintenance yard. Most of the common yellowthroat sightings for the Caltech bird walk come from that one bird wintering now over by the Millikan ponds. Say's phoebes also exemplify this effect. In a typical year, typical being defined as anything more recent than 1998 (1999 was the first year they appear in the Caltech species listing), we will see a Say's on two or three walks but, in the winter of 2002-2003, it was nine in nine weeks and, in the winter of 2009-2010, it was 17 sightings over 21 weeks. Does this mean that Caltech is being inundated with Say's phoebes every now and then? Not at all. In the Fall, around weeks 39-42 (late September to early October), we get a pulse of Say's phoebes passing through Caltech as they migrate north and west out of the desert for wintering. We often see one of these birds as he/she pauses mid-migration and forages around Caltech. In 2002 and 2009, one of these birds apparently plopped down on the fence at the baseball field or the track and decided that the offerings here were pretty good and that the palette available in Ventura was not going to be any better. We then get Say's phoebe sightings by the bunch. More commonly, a Say's phoebe will abrogate our fields starting late in the year (week 47-51) and we will pick up two to several sightings between late November / early December and late February / early March. I don't know if this reflects different batches of migrators (e.g., Baja vs. Arizona), different groups (e.g., adult versus juveniles), or mobility within wintering grounds. We get another pulse of what are likely to be snacking migratory birds heading back to their breeding grounds during weeks six to eight. Last sightings for the winter have not extended beyond week 10 for us (i.e., the first week of March). So, we have a shot at picking up another Say's phoebe in the next couple of weeks but there are, of course, no guarantees. So, where is the bias? Twenty-six of our 63 Say's phoebe sightings, about 40% of all sightings, may have come from just two birds. When you factor in the likelihood that other sightings falling on successive weeks (seven examples) also reflect a single bird contributing more than one sighting, it seems likely that treating our Say's phoebe sightings as an unbiased sample of the population passing through campus would be in error by a factor of two or three. The listing is a terrific resource but you can't be cavalier with it.

I leave you with a mystery. Why do Say's phoebes not appear on the Caltech bird walk before late 1999? It is not plausible to me that a Say's would not have been correctly identified on the walk between 1986 and 1999 if one had been seen. These are very distinctive flycatchers and they have been passing through Pasadena for a long time. It seems unlikely that something major happened in the San Gabriel Valley during the mid- to late nineties that led to funneling of migrating Say's phoebes onto campus. I think it is more likely that something happened with the playing field or adjacent construction that made the area more attractive. However, construction of Braun substantially predates 1999 and undergrounding of the parking structure and construction of Cahill post-date it. Perhaps some of the "old-timers" can help with this.

The date: 2/21/2012
The week number: 8
The walk number: 1131
The weather: 73°F, partly cloudy

The walkers: Alan Cummings, John Beckett, Vicky Brennan, Tom Palfrey, Viveca Sapin-Areeda

The birds (20):

Northern Mockingbird
House Finch
Anna's Hummingbird
American Crow
Mallard
Yellow-rumped Warbler
Black Phoebe
Red-tailed Hawk
Ruby-crowned Kinglet
Townsend's Warbler
Say's Phoebe
Cooper's Hawk
Band-tailed Pigeon
Spotted Towhee
Lesser Goldfinch
Bushtit
Common Raven
Hummingbird, Selasphorus
Yellow-chevroned Parakeet
Common Yellowthroat

-- John Beckett

Respectfully submitted,
Alan Cummings
2/27/12

http://birdwalks.caltech.edu/index.html






2/13/12

Sometimes, the weather is wonderful and the birds uncooperative. Sometimes, the weather is wonderful and the birds are everywhere. Sometimes, the weather is bad and the birds are absent. Well, that's not right either. This week, the weather promised to be a cool post-rain show according to Alan's radar analysis, so Vicky and I voted to proceed with the walk, even though we knew that Tuesday was going to be unambiguously clear and likely to bear an extra birder or two and, even more likely, some extra birds. Alan was amenable to going either way. So, with the votes counted, we set off, drizzle following in our wake. In the Maintenance yard, we picked up our first highlight, a Cooper's hawk. She (based on size) announced her presence by keeing, while still out of sight, off towards the gym, but then she glided into full view for Vicky and myself as she passed over the Maintenance yard. Alan was down in the jungle, scaring spiders and squirrels, but the bird landed in a tree within his field of view, so we all got a good look. The baseball field yielded no sparrows but highlight # 2 was perched on the chain link fence about 5 meters away, a Say's phoebe. These flycatchers winter in our area and breed in the desert, apparently with little or no interaction with black phoebes, whose wintering range, they overlap, because we see never see an obvious hybrid. By the time we entered Tournament Park, it was raining enough to make me wish that I had brought my umbrella. Vicky was tucking her hair up underneath her baseball cap and hoping for enough protection to prevent a major outbreak of the frizzies. We briefly took cover under some small trees at the east end of the park but decided to sally forth across the field, knowing that there was formal cover at the other end of the park if we really needed it. The third highlight, and the one that eventually yielded the species of the week, was seen in Tournament Park and I discuss them below. The rain ceased by the time we got to Wilson Avenue and, by the time, we got past California, it was partly sunny and so much warmer that I was thinking about taking my sweatshirt off. This was probably the most changeable weather I have encountered on the bird walk. The last species of the day was also worth mentioning. Usually, if we have mallards in residence, I, or one of the other walkers, picks them up in one of the Millikan ponds along the way to the starting point of the walk. This time, I didn't see them, which I thought at the time, did not bode well for our walk. At the end of the walk, however, Alan spots a pair of mallards tucked up under the ledge fronting the Millikan reflecting pool. Although mallards make their living in and on the water (keeping kitty kibbles out of it), this pair apparently only wanted to get wet when and where they wanted to get wet and not when and where some leaf drop might decide they were going to get wet. So, with better intuition than we had, they decided to float the rain out in comfort and safety. With the ducks, we were up to a total of 17 species for the walk. This may not sound like much, as it lies only two above the lowest total ever for week 7, but I submit that a walk with three legitimate highlights and one cute curiosity should feel no need for apology. I enjoyed it.

See the plots at http://birdwalks.caltech.edu/bird_data/species_time.html and http://birdwalks.caltech.edu/bird_data/two_plots.htm

What do we have for the bird of the week? We are in Tournament Park and I am scanning trees, when Vicky suddenly starts yelling (nicely) "Look! Look!! Look!!! Look!!!!" A squadron of a dozen gulls was flying at low level just to the east of us. They formed a vee with a couple of birds off vee at the end of one limb. Now, most of our gull sightings are at long distance, so gull species is the best we can do. This time, we are close enough to look for details. The first impression was of light gray on top with white below, most likely making them one of ring-billed or California gulls. My immediate thought was to work with the bird closest to me but I could see that the two closest birds, both of which were off vee, had some intra-wing markings suggesting second or third winter birds. I can usually figure out a gull if it is close to me, sitting still, and patient but juvenile gulls sustain dramatic changes in plumage and coloring as they age, and that can make typing species problematic, especially if you only have a few seconds. So, I moved into the vee, where the adults were, and concentrated on the head of one bird. It was a little streaky with a yellow bill and a sharp black ring cutting across it, aft of the tip, no visible gonydeal spot next to the ring, and a lightly colored eye (at least not really dark). I moved back to the wing tip and could see black right at the tip with a white splash below. The feet were in the yellowish regime (i.e., not pink). All of these features were consistent with a ring-billed gull and a couple were inconsistent with the most likely competition, a California gull. So, we had acquired a flock of ring-billed gulls.

Ring-billed gulls have done very well and very poorly with human intrusion into breeding and wintering areas. In the late 1800s, the population was seriously stressed because the Great Lakes and many smaller lakes and rivers, whose islands were used for breeding, were turning into cess pools with declining fisheries, there was rampant killing of gulls for their feathers and as food, and there was human development on many of the islands used for breeding. Ring-billed gulls became a somewhat protected species under the 1917 Migratory Birds Convention and made out like bandits when we began major programs to develop alewife, smelt, and salmon fisheries. We also tend to suppress populations of mammalian predators and Americans produce the most and best human garbage in the world. The net result is that the U.S. population of ring-billed gulls has increased twenty fold over the last century, more than the corresponding increase in the human population (3-4x). As is usual with such things, the largesse comes with unintended consequences. More and bigger ring-billed gull colonies means competition with tern colonies and, over time, reduction in tern and plover populations. Moreover, every ring-billed gull is hard- wired to be a kleptomaniac. Why work to catch your own fish if you can steal one from a tern, a grebe or a kingfisher? The success rate is modest, maybe 10%, but this still can't help but reduce fitness in the victimized species. The timing on our latest gull species sighting is typical of historical Caltech bird walk results. Gulls first appear over Caltech around week 45 and we generally last see them around week 13 - 16, although you can have a (rare) sighting at any time during the year. Sightings appear to be somewhat cyclical but they have been generally declining with time, from a peak of 12 in 1994 to an average of around three over the last several years. The effect is pretty clear if you take a four year running average to clean up some of the noise. Since the overall population of ring-billed gulls in the state and country has been increasing, not decreasing, over the last couple of decades and the number of eyes that might reasonably see a gull on the Caltech bird walk has also been increasing, not decreasing (which is why turkey vulture sightings are up), this suggests that we are witnessing a localized phenomenon. Just to throw out a sample possibility, something like opening, closing, or rescheduling in the filling of regional landfills, could lead to a change in the local noontime flight patterns for our wintering gulls and leave us with fewer to see.

The date: 2/13/2012
The week number: 7
The walk number: 1130
The weather: 54 F, cloudy, partly cloudy, partly sunny; partly drizzled with one period of full scale rain; no tornadoes were noted

The walkers: Alan Cummings, Vicky Brennan, John Beckett

The birds (17):

Rock Pigeon
Mourning Dove
House Finch
Anna's Hummingbird
American Crow
Yellow-chevroned Parakeet
Yellow-rumped Warbler
Lesser Goldfinch
Red-whiskered Bulbul
Cooper's Hawk
Say's Phoebe
Ruby-crowned Kinglet
Ring-billed Gull
Bushtit
Black Phoebe
Woodpecker, species
Mallard

-- John Beckett

Respectfully submitted,
Alan Cummings
2/17/12

http://birdwalks.caltech.edu/index.html






2/6/12

I am reminded in a vulture's glide that motion is the staying thread of life, even in a vulture's passive lofting, drawing soaring heights from warmth. I can feel the warmth but can I shed the day as easily as he sheds the height? Sometimes it is simple. You are a finch flying for your life. A sharp shinned is closing. Do you make the bush? Do you die? You want to live and put everything you have into escape. The hawk wants you to live. Life wants to live. It is our most consonant power. This week seemed to be about renewal. There are white-throated swifts in Pasadena, although I haven't seen them on campus. We usually begin seeing them in earnest around week nine but maybe they will appear a little early this year. Darren was back from his polar wanderings, giving us a badly needed expert on penguin identification, and we had our first four warbler day in nearly four months (last happened on October 10). I note for later reference that these events were not unconnected. It might have been even more impressive if our common yellowthroat had not, apparently, moved along a few weeks ago. We might have had a shot at five warblers. Nevertheless, the species total of 23 was a tick up from last week and symmetrically disposed for this week, four above the median and four below the record.

See the plots at http://birdwalks.caltech.edu/bird_data/species_time.html and http://birdwalks.caltech.edu/bird_data/two_plots.htm

One first half highlight was a terrific view of a mountain chickadee across the driveway from Morrisroe. This bird was busy pummeling a nut and ignoring us, twenty feet away. This bird brought us a third chickadee week of the year and our second excellent viewing. Perhaps our chickadees are becoming a little less shy of people. A second highlight was Carole's capture of a turkey vulture. That's our second turkey vulture week of the year and consistent with our tendency for picking up sightings of this species in the first third of the year. A lot of people seem to hold turkey vultures in ill repute but without Carole's vulture and a couple of birds Darren picked up later, we would have been in danger of dropping below 20 species for the week.

So, we find ourselves in Darren time once again. I felt this as a subtle, sometimes not so subtle, aural lift throughout the walk but the birds were mostly on the quiet side, so the impact of having Darren back was not too in your face obvious until fairly late. The first major eruption was an assertion in the midst of Avery garden that cedar waxwings were in the air. A few seconds later, he repeated the warning. Now, this in and of itself is not a special case although I find it a bit spooky, just as it does when Beth, who also has excellent hearing, is on the walk. It did, however, give us a warning of several seconds and when a small flock of cedar waxwings flashes overhead, we are ready. Now, cedar waxwings in flock are so distinctive that I think we would have nailed them without Darren but the second event was classic Darren and yielded an unmistakable enhancement in the species list for the day. We are, again in Avery garden surrounded by a verbal and visual cacophony, dozens of bushtits. Darren, however, hears more. He hears two warblers. One is a Townsend's and the other is a black throated gray. Both are calling in the midst of the legions like froth on a wave. Would we have seen them, much less heard them without Darren? No.

Change is the only constant, even for Caltech and even for the bird walk. Alan had a chat with one of the Maintenance yard workers and was told that the Maintenance yard is going to be eviscerated to form a new Child Care Center. So, we will lose the last of the roughage lots on campus, a sad event for Caltech birding for at least two reasons. In my experience, there is a substantial drop in ambient bird populations for a one or so block area around a major construction site, which is likely be active for a couple of years, given Caltech's usual approach to these things. So, that's not good for us in the short term. Second, once the new construction is completed, it will be garnished with what I am sure will be typically robust bird poor plantings, so the ambient local bird population will never recover to pre-construction levels. That's bad for us in the long term. It is, however, impossible to argue with the need. There is currently a two year waiting list to get a child into the day care center unless you happen to be one of the anointed ones (aka faculty), so you have a de facto bigotry and insensitivity built into the system, leading to resentment, depleted morale, and loss of employees. Let's face it. Caltech is grotesquely under serving young families. This reflects poorly on the Institute now and it has been a systemic, studiously ignored, festering problem for decades (at least two that I know of). Something has changed. Did the firmament shake? Did we lose a prized candidate or ten because of the rotten accommodations available for dependents? Is it the new administration? Whatever the cause, the Institute has apparently awakened from some deep notorious slumber, recognized the existence of a fundamental need, if not inequity, and is, at last, planning to do something about it. I am sad for the likely negative impact on the bird walk, although there is an opportunity here to develop an enthusiastic batch of little birders. They may partially compensate for the degradation of habitat by finding birds for us before we arrive. I am also very happy for the many mothers who might otherwise never be.

The date: 2/6/2012
The week number: 6
The walk number: 1129
The weather: 69°F, partly cloudy

The walkers: Alan Cummings, Viveca Sapin-Areeda, Carole Worra, John Beckett, Darren Dowell, Vicky Brennan

The birds (23):

Mourning Dove
House Finch
Anna's Hummingbird
American Crow
Yellow-rumped Warbler
Mallard
Band-tailed Pigeon
Black Phoebe
Ruby-crowned Kinglet
Lesser Goldfinch
Red-whiskered Bulbul
Yellow-chevroned Parakeet
White-crowned Sparrow
Bushtit
Orange-crowned Warbler
Mountain Chickadee
Hummingbird, Selasphorus
Turkey Vulture
Hawk, species
Downy Woodpecker
Cedar Waxwing
Black-throated Gray Warbler
Townsend's Warbler

-- John Beckett

Respectfully submitted,
Alan Cummings
2/9/12

http://birdwalks.caltech.edu/index.html






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