Favoritos de susanmcrae

On Wednesday, August 26, 2015 at 1:45 pm, H.T. Harvey & Associates ecologist Maya Goklany and I discovered three California black rail (Laterallus jamaicensis coturniculus; black rail) chicks, accompanied by a single adult black rail, just off the main boardwalk, northwest of the parking lot at Alviso Marina County Park in Alviso, CA, located in Santa Clara County. We were making a quick visit to the park to scan the salt ponds for migrating birds. The black rails were encountered on the way back to the parking lot just off the western side of the boardwalk. Unknown, loud, peeping calls were first heard by us at approximately 1:45 pm. Upon investigation of the area where the peeping was coming from, we saw three, very small (~ 1.75 “), black, down-covered chicks approximately 2-3 feet from the west side of the boardwalk, climbing over the matted down, dead stalks of bulrush, found on either side of the boardwalk. The chicks were seen on the north side of the tidal channel that runs underneath the boardwalk. I noted at least two other peep vocalizations coming from the south side of the tidal channel, approximately 40 feet from where we saw the three chicks. The chicks were moving southwest to northeast and appeared to be responding to a repeated high, single-note, clicking, wet sounding “kwip” vocalization that seemed to originate directly from underneath the boardwalk. We looked directly below along the west edge of the boardwalk and could see the back of a small, sparrow-sized bird that was partially hidden in the shadows of dead bulrush stalks. I used my binoculars (Eagle Optics Ranger ED 8x42) to focus on the back of the bird which was approximately 5 feet down from the top of the boardwalk and could make out a dark back, speckled with white, and what appeared to be a dark rufous-colored nape. The bird was turned with its head hidden by the bulrush stalks towards the north, with its tail pointing towards us. I was able to get a 4-5 second look, at which point the bird turned its head towards the approaching chicks. The head and bill appeared small and dark. The bird then disappeared quickly into the heavy bulrush cover towards the west. A pair of faint “growl” vocalizations were then heard, at which time the peeping and other vocalizations stopped. Based upon the quick look that I had within heavy vegetated cover, I was quite certain that we had just observed a black rail adult and its chicks. Neither of us had a camera with us at the time, so we were not able to get a photo or audio recording at the time. I informed colleagues at the HTH office when we got back and then I revisited the location later that afternoon at 3:00 pm, but did not observe any chicks or the adult. I did hear growl-like calls at 4:05 pm, and then left the site at 5:00 pm.
Thursday, August 27, 2015
I returned to the boardwalk sight location the next morning at 6:40 am. I set up my camera (Canon Powershot SX30 IS, 14.1 mp, 35x optical zoom) on a tripod on the boardwalk next to the location where we had first spotted the black rail chicks and adult, in order to record any calls or photograph the birds themselves. I started recording video (video upon request) at 6:46 am, which captured repeated, clicking, “kwip” calls, coming from the west side of the boardwalk, which I had heard the previous day. The calls continued for the next three minutes, at which point, my second video (video upon request) captured two adult black rails fly out of a clump of bulrush in opposite directions, on the west side of the boardwalk, with the calls becoming quicker and more frequent. The adult black rail that flew out of the frame of the video to the south (left frame) then flew back to the spot where the other adult bird was located. Out of the left-frame of the video, to the south, I observed one black rail chick briefly on top of the matted down bulrush. The adult birds then appeared to forage in this area for the next two minutes. The birds then disappeared into the heavy bulrush vegetation, continuing to call, which I was able to follow to the other side of the boardwalk. On the east side of the boardwalk, I observed two adult black rails, male and female, brooding three chicks. Video capture starting at 6:54 am (video upon request) shows one chick moving towards the adult male and then climbing underneath the adult’s breast. Directly to the left of the adult male was the adult female who was brooding two chicks underneath her breast feathers as shown in a subsequent video (video upon request). Both adult birds remained in this position, silent, brooding chicks for the next 10-12 minutes. At approximately 7:15 am, the adult male bird got up and moved underneath the boardwalk to the west. The chick that was underneath him moved into the vegetation towards the back of the female and disappeared. I am not certain if this chick followed the male or not. I did not capture this on video. I then started to hear the “kwip” calls from the west side of the boardwalk. Video capture (video upon request), starting at 7:29 am, and subsequent videos (videos upon request) showed the adult male bird foraging in the same area where they were foraging earlier. He continued to call as he foraged. The female adult bird continued to stay on the ground on the east side of the boardwalk. At one point she moved deeper into the vegetation, while I was watching the male forage on the west side of the boardwalk. I was quiet and still and did not lean over the marsh to avoid disturbing the rails, and they did not seem perturbed by my presence.
We had decided not to publicly announce the previous day’s observations (e.g., on the South-Bay-Birds listserv) to avoid having too many birders and photographers disturb the birds. However, we alerted a few Santa Clara County bird records-keepers whom we could trust not to disturb the birds, to assist with documentation of the record. County records-keeper Bill Bousman arrived to the site at ~8:00 am. We both observed both adults on the east side of the boardwalk sitting and preening, presumably with their chicks underneath them. At ~8:50 am, Bill and I watched the adult female stand up, preen and move off to the northwest. When she moved we saw two chicks underneath her. The second adult, who had moved underneath the boardwalk, was then seen walking west to east very fast and disappearing into the vegetation. During this period both adult birds continued to give their “kwip” calls. After 9:00 am, the adults and chicks were not heard nor seen again. Richard Jeffers arrived at 9:30 am. I then left the location at 9:45 am.
I returned that evening at 6:15 pm to try and relocate the birds. It was very windy, and there was a lot of foot traffic on the boardwalk at the time. At 6:56 pm I heard 3 short “kwip” calls, northwest of the boardwalk. It sounded somewhat distant. At 7:33 pm I heard a short growl call on the west side of the boardwalk. No other activity was noted, and I left the site at sunset.