Caltech Birding

10/28/08

(Corrected to add Band-tailed Pigeon that Ashish saw near IPAC)
I think it was Glenn who said during the walk that we had quality if not quantity. And that we did. We only got 14 species, 1 below the median for a week 44, and it was a low-scoring walk -- based on number of species.

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

But it scored high with me on other grounds because we saw the Red-naped Sapsucker! It wasn't in the sapsucker tree, however. It was in an oak tree behind IPAC. Very interesting. We haven't seen one of those in a long time. This is the 9th time to see one in 22 years; the last time was in 2002.

Also, in the same tree with the sapsucker was a Black-throated Gray Warbler. And today marked the first Ruby-crowned Kinglet of the Fall season. So, it was a good day overall.

The stats:
The date: 10/28/08
The week number: 44
The walk number: 959
The weather: 91F, sunny
The walkers: Alan Cummings, Glenn Hamell, Jim Carlblom, Viveca Sapin-Areeda, Ashish Mahabal, Darren Dowell

The birds (14):

Scrub Jay
House Sparrow
House Finch
Anna's Hummingbird
Acorn Woodpecker
Crow
Yellow-rumped Warbler
Ruby-crowned Kinglet
Bushtit
Black-throated Gray Warbler
Red-naped Sapsucker
Black Phoebe
Lesser Goldfinch
Band-tailed Pigeon

Respectfully submitted,
Alan Cummings
10/29/08
http://birdwalks.caltech.edu

10/21/08

Another walk, another record. But not the good kind of record. We got the lowest total for a week 43 of a year. We saw 10 species, one less than the minimum for a week 43.

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

I have been wondering how this year stacks up against previous years. It seems like we are having a down year. If you look at the plots above, we have set or tied the record low 6 times this year. That seems bad. But we have tied or set the maximum record three times. So I decided to develop a ranking system. I discarded the first and simplest method that came to mind, just total up the number of species seen during the year and divide by the number of walks during the year to get an average number seen on a walk that year. I decided that there could be some definite bias in that method, if for example, more walks took place in the slow summer months in one year as compared to another. So I looked into more unbiased methods. I came up with four ways to score each walk.

1) Make a linear scale from zero to one. Walk score = 1 - (number_walks_in_that_week_with_higher/(number_walks_in_that_week - 1)) So if you look at all the walks taken during the same week, if no walks had a higher number then score for that walk is 1. If all the other walks had a higher number, then the score is zero.

2) By how many species does the walk in question deviate from the average number observed for that week of the year. I gave a walk that score. It can be plus or minus.

3) By how many standard deviations is the number observed away from the average number observed for that week of the year. That's a score.

4) By how many SIQR (semi-interquartile range) is the number observed away from the median number observed for that week of the year. That's a score.

I then compute a yearly score (or ranking points) by averaging the weekly scores for the year. It turns out that all four methods gave about the same result. The best year was 2002, followed by 2007 and then 1990. The worst year was 1987, the first year I included in the analysis. I decided on method 2 as the one to use.

I have put this plot on the website. It's on the species_time page, second plot down from the top. We are having a sub-par year but not by much. So, I feel better. It's not as bad as I thought. We are a bit negative, so come on out and join in to turn this year into positive territory.

Side note: in this scoring system, the walk scores will change each week, but right now the absolute worst walk was walk number 11 held in week 3 of 1987 with a score of -2.91. The best walk occurred on 3/30/06 (week 13 of 2006, walk number 827) with a score of 3.15. It was also the week with the highest number ever observed, 31. The lowest number ever observed was 6, which also occurred in 2006 on 9/12/06 (week 37, walk number 849). But the score was only -1.97, not the worst according to this method. The walk we had today scored -1.59.

The stats: The date: 10/21/08
The week number: 43
The walk number: 958
The weather: 80F, sunny
The walkers: Alan Cummings, Glenn Hamell, Beth Moore, Viveca Sapin-Areeda, Fiona Tindall

The birds (10):

Rock Pigeon
House Sparrow
Mourning Dove
House Finch
Anna's Hummingbird
Crow
Yellow-rumped Warbler
House Wren
Black Phoebe
Lesser Goldfinch

Respectfully submitted,
Alan Cummings
10/23/08
http://birdwalks.caltech.edu

10/14/08

Gee, it was nice day with the temperature at 80F and clear as a bell. I'd seen White-crowned Sparrows at my bird bath in the morning before I came to work. I had high hopes. But when we got to California Blvd. we had only four species. Fortunately, things picked up from there on and we finished with 13, two short of the median for a week 42, and four above the record low of 9. See the plots at http://birdwalks.caltech.edu/bird_data/species_time.html and http://birdwalks.caltech.edu/bird_data/two_plots.htm

Our highlight bird was a Nuttall's Woodpecker seen in the oak tree at the intersection of Wilson and San Pasqual. We haven't seen one of those in quite a while. We also saw a nice flock of Cedar Waxwings land in a tree across the street at the same location. And in the oak tree with the Nuttall's was a large flock of Bushtits. And then a group of four Turkey Vultures circled near that corner. That was definitely the hot spot on the route this week.

What seems to be killing us are the "regulars." They are hiding out. We had no doves of any kind: no Rock Pigeon, no Mourning Dove, and no Band-tailed Pigeon. And we didn't see a Mockingbird or an Acorn Woodpecker. Highly improbable. Something is going on. In the good old days, we'd check off all nine regulars on a regular basis. I guess it's like the Dow Jones; maybe I should drop some of these losers off the regular list and elevate the Black Phoebe and Bushtit to the list. But I'd have to change my listing pad, so I probably won't do that.

The stats:
The date: 10/14/08
The week number: 42
The walk number: 957
The weather: 80F, sunny
The walkers: Alan Cummings, Glenn Hamell, Viveca Sapin-Areeda, Beth Moore

The birds (13):

Scrub Jay
House Sparrow
House Finch
Anna's Hummingbird
Crow
Yellow-rumped Warbler
Black Phoebe
Bushtit
Nuttall's Woodpecker
Turkey Vulture
Cedar Waxwing
Lesser Goldfinch
Hummingbird, Selasphorus

Respectfully submitted,
Alan Cummings
10/14/08
http://birdwalks.caltech.edu

10/7/08

(Viveca saw House Sparrows on way back to her office -- they've been added. Text of report not changed except 12 to 13 sightings.)

Well the yellow-rumps have returned to Caltech! And right on schedule. From the historical data there was a 95% chance we'd see them today and we did. The Yellow-rumped Warblers have a good clock in them. Somewhere in about a two period from week 39 to week 41 they arrive for the winter season. They depart over a similar short interval in the Spring. Kind of interesting.

That was the good news. The bad news was that we barely scraped together 12 species, which tied us for the record low for a week 41. See the plots at http://birdwalks.caltech.edu/bird_data/species_time.html and http://birdwalks.caltech.edu/bird_data/two_plots.htm

It was hot. Not the birdwatching, the air temperature. Not as hot as last week but still a bit uncomfortable. Six birders started out but only three made the finish line. However, I think only one departure was directly heat-related. Better luck to us all next week.

The stats:
The date: 10/7/08
The week number: 41
The walk number: 956
The weather: 90F, sunny
The walkers: Alan Cummings, Glenn Hamell, Viveca Sapin-Areeda, Simon Radford, Kent Potter, Darren Dowell

The birds (13):

Scrub Jay
Mockingbird
House Sparrow
House Finch
Anna's Hummingbird
Acorn Woodpecker
Crow
Yellow-rumped Warbler
Red-tailed Hawk
Black Phoebe
Bushtit
Lesser Goldfinch
Hummingbird, Selasphorus

Respectfully submitted,
Alan Cummings
10/7/08
http://birdwalks.caltech.edu