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Contra Costa Migrant Action (delayed report)

Ethan Monk <z.querula@...>
 

Hi All,

A slightly delayed report on some general migration patterns around Contra Costa recently. Feel free to not read this whole post as it is way too long. (For the Richmond WTP summary skip to the end of this verbose email)

Sunday (9/1) I was accompanied by Mark and Lucas Stephenson through some sites in Richmond. Point San Pablo was first, as it should always be whenever birding Richmond in the fall, and we were surprised to have the winds blowing SE at the point and have completely clear conditions, with a sizable fog bank to our East. I'll save everyone an exhaustive list of what we saw, although know we saw at least 92 (yes, 92) passerine migrants in a little less than 3 hours. This wasn't my best day by sheer numbers--Oct. 7 of last year I tallied almost 200 passerine migrants in 3 and a half hours-- but it was my most exciting by far. The highlight of the outing were 3 Purple Martin migrating N to S over the point, as well as a Yellow-breasted Chat (second Richmond record, great spotting Mark!) foraging beneath the water tanks with around 15 tanagers. The fact that the chat and at least 10 or so tanagers have remained for at least two days is notable in that not all migrants passing through Point San Pablo leave by late morning. Warblers were abundant (I counted 46) and almost all were gone by the time we left, on the other hand.

If you ever bird Point San Pablo, I recommend arriving at sunrise or a few minutes before in the parking lot to the yacht harbor. From there, walk the curvy road up until the water tanks, making sure to bird the swales between the bends. That is generally the direction of movement at the Point. Even an hour or two after sunrise, the movement will have already stopped, and many birds will have left. It is imperative you arrive early morning for maximum bird numbers. In some places you stop seeing birds because it gets hot outside. At Point San Pablo you stop seeing birds because most of them literally leave.
eBird list: https://ebird.org/view/checklist/S59432440

We checked a few other spots, Booker T. Anderson Park, Creekside Park, Wildcat Creek--in all places minimal activity.

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Saturday (8/31) I met Mark and Lucas Stephenson at Piper Slough at 7:46 am for a quick 50 minute foray through the willows. Pishing at various locations pulled up 2 Pac-slopes, at least 7 Willow flys (easily 8 or 9) and 21 warblers. 1 Mac, 9 yellow, 4 Wilson's, 2 BTgray, along with 2 tanagers, a Black-headed grosbeak and a bunting. Considering we didn't even round the first bend at Piper, it is highly likely that we missed quite a few migrants, presumably mostly Yellow Warblers and Willow Flycatchers. If you want to see this many migrants at Piper, make sure that you actually enter the willows--many migrants (especially warblers) tend to stay away from the fringe habitat on the willows' outer most edge. If you actually walk 10-20 feet into the willows, you are likely to see much more.
As well, one of the two California Towhees that resides on Bethel Island made an appearance today. This is the first time I have seen this species on Bethel although there has been a pair out there for a while now.

(And if anyone cares anymore, at least one Bank Swallow was still around)
eBird list: https://ebird.org/view/checklist/S59398824

Next, we caught the 9am ferry to Bradford (I really don't want to get into access issues, but if we aren't allowed access why would they sell tickets at a gas station) where I think there was little out of the ordinary besides TWO counter-singing Bell's Vireos in the middle of the island. I'm assuming that means that all this year (and presumably last year as well) there were two active territories, but at least one was repeatedly overlooked? While it isn't too early for a migrant Bell's (the first county record was found only a few days from now, on Sep. 11) I doubt that this second bird is a migrant. Also of note were around 30 Yellow Warblers (seems notable considering the time of day) and 12 Willow Flycatchers, which should be an expected number on Bradford this time of year. Willow Flycatchers move through the delta in large numbers now (I think we had 24 in total Saturday) but I am unsure if people are aware of how common they can be, especially if you are making a point of checking the right spots.
eBird list: https://ebird.org/view/checklist/S59404681

As well, Byron WTP was of interest (unusually) for the 38 Greater Yellowlegs hanging around. It's getting late, but still a good place to check for Solitary Sandpiper... eBird list: https://ebird.org/view/checklist/S59412224

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Jumping back to last Wednesday (8/28), I checked the Meeker Slough high tide roost, which is typically most visible around 3.5 feet. Decent roost with about 100 Willet, 50 Godwit, 1 G. Yellowlegs, a few dows (both species), about 20 Black-bellied Plover and 30 some r.n. phalaropes (split between the bay and the Northern side of the trail). As well, there were decent numbers of peeps strewn through the pickleweed on the far shore--quite easy to overlook. About 40 Western, 25 Least and 2 Baird's eventually flew in, which despite their large size vanished quite quickly. A few black turnstones were around as well as a tattler, and I think a Ruddy could show up here soon. I recommend continually checking this high tide roost over the next month, as this is a good site for Snowy Plover, Least Tern and potentially golden-plover. The level of coverage the past few days has been surprisingly good compared to previous years.
eBird list: https://ebird.org/view/checklist/S59336044

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To deal with Richmond WTP--as many people know, we saw one peep only, an apparent Semipalmated Sandpiper which was gone within a couple hours. While I don't believe that this peep is a Little Stint, I will be leaving it as shorebird sp. until I receive some more opinions, but I might end up chalking this bird up as a Semipalmated Sandpiper in the end. At this point, the only two options for this bird (in my mind) are Semipalmated Sandpiper and shorebird sp. Even if it is a Little Stint, our photos are not good enough for a definite confirmation and no birders with Little Stint experience saw the bird in the field. If the possibility of Little Stint remains, it shall remain shorebird sp., if not Semi Sand. Whether or not it could be a Little Stint is for others to judge--I do not understand many facets of this identification. That being said, I have read up quite a bit in the past two days on both Semipalmated Sandpiper and Little Stint, and considering the extent of regional variation of bill shape/length of Semipalmated Sandpiper, I do think the slight oddities some have seen in the bill are within reason for Semipalmated Sandpiper, albeit definitely not something I would consider normal. When I decide what to do with this bird I will update my eBird list with a hefty description, but for now this over the top listserve post is enough for me. But I think it's a Semipalmated Sandpiper.

Anyway, good birding,

Ethan