My original motivation for this trip was to participate in the Barra de Potosi Christmas Bird Count (CBC). After a relaxing morning at my hotel in Zihuatanejo, I lugged my bags a few hundred yards over to where I could catch a bus to the airport, from where I was able to transfer to a bus to Barra de Potosi. On arrival I dumped my gear in the room at El Nido and connected up to the wi-fi so I could communicate with Laurel Patrick, the count organizer, and Santiago Castro, a local birder who I would be birding with on Saturday morning and on the actual count, which was on the Sunday. Laurel is the founder of El Refugio de Potasi, where injured or orphaned local wildlife that cannot safely return to the wild can find a home.
Once I had sorted out when and where I would be meeting Santiago, I wandered down to the mouth of the lagoon, hoping to find something on the sandbanks. Although there is a lot of disturbance from fisherman and tourist wading around in the lagoon mouth, there are usually some birds around. Checking the flocks of Brown Pelicans, terns and Laughing Gulls on the sandbanks, I was delighted to see a first-year Heermann’s Gull. Although I had my camera, I was not able to zoom the camera properly and ended up with even worse shots than I normally get, if such a thing is possible! Fortunately, the remaining photos in this blog entry are courtesy of Santiago.
Once I got back to my room, I discovered that the camera had
been in some kind of video mode. While this explained the inability to fully
lock in on a distant target, it also meant that I that I had lower resolution
images and now had to extract them from the video. After several false starts,
I eventually found a web site that would convert the video into a bunch of
separate images. From there it was simple to create an image I could use in the
ebird list.
The next morning, Santiago met me outside the El Nido and we
took the very short boat ride across the lagoon mouth to an area called Gaumilule.
This was mostly a loop along the edge of the mangroves and scrub forest with a
section along a beach and some vegetated dunes. I introduced Santiago to the
concept of the mobbing playback and he was very impressed with the results.
After a slow first stop, the second stop produced a Black-vented Oriole along
with numerous Yellow-winged Caciques and usual warblers, gnatcatchers and
hummingbirds. We also picked up some resident species such as Lineated
Woodpecker and Citrolene Trogon. A couple of Ash-throated Flycatchers enabled
us to hone our myiarchus identification skills.
Further along, during another ‘mobbing attraction’ event, Santiago drew my attention to an unfamiliar warbler that I was immediately able to see was a dull immature Cape May Warbler! Although, I suspect a lot of the “eastern vagrants” I have recently been seeing on my Guerrero trips are not really that rare, Cape May is probably actually rare here, given its status as a vagrant in California. It was also nice for me to see one of these dull ‘gray-and-white’ Cape Mays, as opposed to ones with obvious yellow in the underparts. I had often wondered how obvious these would be compared to a Yellow-rumped. Well, the answer was it was very obviously different, especially the face pattern and bill size and shape.
We continued onwards, making regular stops. Both Santiago
and I had separate Northern Parula sightings, while we also saw a couple of
Tropical Parulas as well. Several Yellow-breasted Chats give great looks. A Golden Vireo was a good bird for being right on the
coast and White-bellied Wren was another Mexcian endemic that showed well. At our lunch stop, where a palm grove bordered the mangroves, the
mobbing crowd included a Yellow-throated Warbler.
Flocks of soaring vultures indicated the presence of
thermals. We regularly checked these flocks and turned up Zone-tailed,
Broad-winged and Short-tailed Hawks, with multiple sightings of the last.
Shortly afterwards, we turned to cross the scrubby dunes and walked along the beach. A combination of dehydration and walking on the soft sand gave me an unpleasant attack of cramps, something I have not previously experienced while actively walking. I eventually worked out I could mitigate the problem by walking on the ball of my foot, which prevented my heel from sinking into the sand and stretching my hamstring. This issue put a bit of a damper on the final section of the walk but reaching a path with a firmer surface and finishing off my water supply kept the problem at bay until I got back to my room, where extensive rehydration and air-conditioning allowed proper recovery.
Santiago also gave me a ride up to the Refugio de Potosi so
I could view the hummingbird feeders. These regularly attract Green-breasted
Mango during fall and spring migration but on previous trips, I had always been
either too late or too early to see one. On this occasion, a few were staying
later than normal and was able to get great looks at least five birds,
including both males and females. I had only seen this species three or four
times previously. There were many Archilochus hummingbirds present but
the only males were all Black-chinned. However, I was able to detect an obvious
female Ruby-throated after closely examining several of the female birds.
Several Doubleday’s or Turquoise-crowned Hummingbirds and at least a couple of
Cinnamon Hummingbirds rounded out the selection.
I had definite concerns about the Sunday walk, which would
be longer and with less shade. I made sure I had an additional water bottle and
drank a lot of water immediately prior to starting the walk. I had neglected to
do this on Saturday, and it turned out that this may have been the cause of the
cramps combined with the soft sand, as I experienced no issues.
The walk was mostly through drying out mangrove punctuated
by areas of open dirt with low vegetation and various lagoons and channels. I
had visited a little of the area once before and found a Palm Warbler, which is
regular there in winter. In addition to checking the warbler flocks, I was very
keen to see Ridgway’s Rail, which Santiago had discovered a few years ago, the
most southerly known location for the species. I had hoped that the lagoon
might be good for shorebirds but some detailed discussions with Santiago
beforehand made it clear that numbers and variety were rather limited.
Once we got out in the drying-out mangrove areas, we started
on some mobbing playback. It quickly became evident that out in that habitat,
the dominant myiarchus species was Ash-throated Flycatcher, a situation
I had not previously experienced in this part of Mexico. Other than Palm
Warbler, of which we saw half-a-dozen, the warbler flocks were not particularly
exciting. A parula sp. got away and by far the most interesting was a celata
Orange-crowned Warbler that was distinctly dull with whitish rather than yellow
below.
Arriving at a good spot for the rails, I tried some playback
and we quickly had three birds responding, including one on the nearside of the
channel we were by. A bit more playback tempted the bird to walk along the edge
of the mangroves where we could see it quite well. A bit further on, I was able
to get a Mangrove Cuckoo to respond briefly to playback, but it did not show
itself.
We were now reaching some larger lagoons, one of which held
a flock of 26 Greater and two Lesser Yellowlegs. We finally reached the north
end of the main salina lagoon, where most birds were concentrated. There was a
flock of several hundred Black Skimmers roosting on an island with small
numbers of Gull-billed and Caspian Terns. The main shorebird concentrations
were here as well with over 600 birds, consisting of Willet, Hudsonian
Whimbrel, Long-billed Dowitcher, Black-bellied Plover, American Avocet and Marbled
Godwit. The lack of calidrids, other than Least Sandpipers that were scattered
throughout the salina area in small numbers, was striking.
We finally made it back to the Refugio, where we could relax
in the shade and drink some more water. I then got dropped at El Nido where I
could change out of my sweat-soaked gear and rest prior to the boat trip out to
Los Morros de Potosi, a large seabird colony. I headed down a little early to
the mouth of the lagoon, where the boat would be leaving from, so I could check
out any gulls. There proved to be even fewer around than normal but while
scanning the feeding terns, I picked out a Forster’s Tern, which eventually
landed on one of the sandbars. Since this would be a new bird for Santiago, I
anxiously kept my eye on it while waiting for the others to arrive. Needless to
say, just as Santiago arrived and I was trying to point out the bird, a couple
of people flushed everything off the sandbar.
The boat ride was very smooth once we were clear of the
shallow lagoon mouth, and we were soon out at the rocks, enjoying the
spectacular display flights of several dozen Red-billed Tropicbirds. We quickly
found a few roosting Blue-footed Boobies and then began to focus on scanning
through the thousands of nesting Cocos (formerly Brown) Boobies to look for
Masked Boobies. This task was complicated by the presence of well-grown Cocos
booby fledglings that had areas of extensive white down on them, creating a
superficial likeness to a Masked Booby when viewed distantly high up on the
island. Eventually our persistence was rewarded with four different Masked
Boobies. Three of these were close enough to clearly see the bills were
greenish-yellow, eliminating the possibility of a vagrant Nazca Booby.
I was too tired to go to a restaurant that evening and just
went back to my room. The next morning, I took a relaxed stroll down to the
lagoon mouth before returning to check out a palm grove on the north end of
town. Although there were plenty of Brown-headed Cowbirds, Inca and
White-winged Doves, the only bird of any interest was a Yellow-throated Warbler
that came into some pishing. It is certainly clear that this species is regular
at low densities in the coastal palms.
At that point, I was pretty much done birding. I spent my
last day in Zihuatanejo enjoying mostly being in an airconditioned room, with
occasional forays to eat.
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