Pelagic Trip Report

Puerto Ángel, Oaxaca, Mexico
5 January 2004

**originally written in 2004 by Andersen and Hosner.  Bracketed text added by Retter in 2005.

To see results from a November 2005 trip, click here.

Trip length: 4.5 hours. Distance from shore: up to 10 miles.

Participants:
Mike Andersen, New York
Ken Behrens, Pennsylvania
Rebecca Green, California
Pete Hosner, Michigan
Rich Hoyer, Arizona
Jay Packer, Texas
Michael Retter, Illinois
Jim Tietz, California

In January 2003, we birded the scrub-forest on the bluffs above Zipolite to the northwest of Puerto Ángel. At dusk we observed a sizable flight of tubenoses to the southeast. The distance was frustratingly far enough to cause a level of doubt in our identifications. We promised ourselves to hire a captain to take us out on a boat if and when we returned.

Nearly one year to the day later, on Sunday, 4 January 2004, we spoke with the Harbor Master in Puerto Ángel. He is located at the base of the pier. He told us we'd find a bigger boat across the harbor. We checked with the suggested captain and quickly realized his boat was no larger than any other in the harbor. Nevertheless, he assured us we could go as far as 10 miles from shore. After a little bargaining, we settled on a price of approximately $270.00 pesos per person for 8 people. This was roughly equivalent to $25.00 USD per person or a total of $200.00 USD for 5 hours. We scheduled a 6:30am departure.

There is a plethora of beachside restaurants that are all quite good and inexpensive. All have a seafood-dominated menu. There are many beachside bungalows and a few hotels in Puerto Ángel and Playa Zipolite including a campground. Part of our group chose the campground while the rest camped on the beach free of charge. As it turns out, this option might not be the wisest as we experienced some theft during the night in Zipolite the following night.

All photographs are by Pete Hosner.

Monday 5 January 2004: We met at 0630 for our pelagic. After receiving life vests we boarded the small fishing boat (Fig. 1) that would take us out on the Pacific. Eight of us plus three Mexicans fit rather comfortably. The only drawback to this boat was that it sat rather low on the water. We could easily reach over and let our hand trail through the water. The benefit was that it allowed us to get close (within 10 meters) to flocks of shearwaters as they rested on the water.

Fig. 1 The boat. Seen here on the beach at Puerto Ángel, Oaxaca. The cement structure on the far left on the horrizon is the the pier across the Puerto Ángel harbor. Jay Packer is pictured facing the boat.

Shortly after leaving the harbor, we swang to the west (right) and headed for the large rock situated off the bluffs by Playa Zipolite. Last year we had upwards of 30 Red-billed Tropicbirds circling here. This morning we found one PEREGRINE FALCON and nothing else. Without birds to entertain us here, we turned south and headed offshore. Within 20 minutes of leaving the rock we started seeing shearwaters flying by. Our first impressions were of large Puffinus species, likely Sooty Shearwater. A few flew by with distinct white markings ventrally that we tentatively called Pink-footed Shearwater. When we finally got a better look at one while the boat was not speeding by Jim Teitz noticed a long graduated tail on the birds and correctly identified them as WEDGE-TAILED SHEARWATERS (Puffinus pacificus), (Fig 2).

Fig. 2. Wedge-tailed Shearwater (P. pacificus) resting on the water. This was the common Puffinus species on our trip. All birds were experiencing heavy wing molt. Light-morph individuals (shown here) comprised about 99% of the individuals. Of about 300 individuals, only 3 were dark-morphs.

In addition to Wedge-tailed Shearwaters, we also noted about 10 GALÁPAGOS [AUDUBON'S] SHEARWATERS (P. [lherminieri] subalaris) (Fig 3). These generally flew by in singles or pairs. We watched them carefully for the hoped for Townsend's Shearwater but could not find any. Townsend's Shearwater is more frequently observed in Oaxacan offshore waters in October than January (Binford 1989).  [A subsequent November trip would prove them to be not very difficult to find.]

Fig 3. Galápagos Shearwater (P. [l.] subalaris) . This obliging individual showed the most white above the eye of any individual we saw on the trip.

One very intriguing observation of "Audubon's" Shearwater was of an individual that displayed "classic" Audubon's marks when resting on the water. As we approached too close, it raised its wings in preparation for flight. At once, all eight of us noticed this bird had jet black wing linings. There was no white to speak of on the ventral side of its wings. Without any references on board we had only our imaginations to help us through the identification. It was not until we consulted Harrison's Seabirds that we found an answer. "In some populations underwings often completely fuscous, e.g. Galápagos Is" (Harrison 1985). Unfortunately, no photographs were taken of this bird.  [Some authors (South American Classification Committee, AOU, version 9 December 2005, Austin et al. 2004) now slpit subalaris from lherminieri as "Galápagos Shearwater".  It is our understanding, though we are not certain, that subalaris is the only taxon in the complex to be expected in Oaxacan waters.]

Over the course of the morning we saw at least three large flocks of shearwaters (Fig 4). The largest flock held about 100 Wedge-taileds. This included at least one dark-morph individual. These flocks consisted mostly of Wedge-tailed Shearwaters with one or two Audubon's and one or two Black-vented Shearwater (Puffinus opisthomelas). These records represent the first Black-vented Shearwater in Oaxacan waters.

Fig 4. This flock was one of three we saw on the trip. Generally, the majority of the flock was composed of Wedge-tailed Shearwaters (P. pacificus) with one or two Galápagos Shearwaters (P. [l.] subalaris) and one or two Black-vented Shearwaters (P. opisthomelas).

Fig 5. Black-vented Shearwater (P. opisthomelas). This was one of about 12 birds we saw on our trip. We often found them in association with large Wedge-rumped Shearwater flocks. Often, there were one or two Black-vented Shearwaters mixed in. This individual shows an average amount of white and gray/brown mottling on the head and nape. Its brown wings are also apparent in this photo. In flight, this made them easy to separate from Audubon's Shearwater. Another field mark, though not entirely apparent in this photo, is the dark bar on the axillaries and secondary coverts. Again, it is evident on this photo, though not as evident as some references make it out to be.

Fig. 6. A Black-vented Shearwater (P. opisthomelas) resting on the water. Again, this individual had a moderate amount of white and gray/brown mottling on the head and nape.

*A note about Black-vented Shearwater: Our first encounter with this species was a small shearwater resting on the water. Most striking was its whitish head and nape. Again, without references on board we were at a temporary loss of what to make of it. We photographed it and observed it resting and in flight. On the wing, the brown mantle and dorsal wing surface was distinctive and unique among the small shearwaters we had seen thus far on the trip. A few of us in the group had experience with this species off California. The brown wings/mantle was the best field mark we had. The identification was supported by the text in Howell and Webb. The North American field guides, especially Sibley, illustrates a range of head/nape color for Black-vented. Some of our birds, especially the first we saw, definitely were paler (Fig. 7) than the lighter adult as illustrated on page 38 in Sibley.

Fig. 7. The 'white-headed' Black-vented Shearwater (P. opisthomelas) pictured here on the left with a Galápagos Shearwater (P. [l.] subalaris) on the right. Aside from the abberant white-headed appearance of this Black-vented Shearwater, this photo serves as a decent comparison to the smaller and blacker Galápagos Shearwater.

More Wedge-tailed Shearwaters:

Fig. 8. This photo is a great comparison of a dark-morph Wedge-tailed Shearwater (P. pacificus) with its light-morph counterpart. This dark individual was 1 of 3 dark-morph birds we saw on the trip. It represents less than 1 percent of the total number of Wedge-tailed Shearwaters seen.

Fig 9. Wedge-tailed Shearwater (P. pacificus) with its wings raised. This photo shows the gradutaed wedge tail nicely.

Fig 10. Another Wedge-tailed Shearwater (P. pacificus) with its wings spread showing heavy primary molt.

Other birds seen:

Other birds seen out there included 1 PINK-FOOTED SHEARWATER that was seen well amidst Wedge-taileds, about 300 BLACK TERNS, 3 POMARINE JAEGERS, 1 RED-NECKED PHALAROPE (Fig. 11), 3 COMMON TERNS, and many LAUGHING GULLS. We also saw about 15 Green Sea Turtles, a double-back-flipping sting ray and the caudal fin of a swordfish. Back at the Zipolite rock we saw two RED-BILLED TROPICBIRDS. One was sitting on the water 25 meters away (Fig 13). A flock of GRAY-BREASTED MARTINS were circling the Zipolite rock and an adult COMMON BLACK-HAWK that was probably a MANGROVE was on the cliffs along the shore.

Fig 11. Red-necked Phalarope (Phalaropus lobatus). One basic plumage bird was seen resting on the water.

Fig. 12. Two Red-billed Tropicbirds (Phaethon aethereus) were hanging out near the Zipolite rock. This beautiful bird took off soon after this photo was taken.

Fig 13. Green Sea Turtle (Chelonia mydas). Not a bird, but the 15 that we saw are certainly noteworthy. A few swam close enough to touch. One even passed under the boat.

The following is a list of all species seen on the pelagic:

Pink-footed Shearwater (Puffinus creatopus) 1
Wedge-tailed Shearwater (Puffinus pacificus) 300
Black-vented Shearwater (Puffinus opisthomelas) 12
Galápagos Shearwater (Puffinus [lherminieri] subalaris) 10
Oceanodromus sp 1
Red-billed Tropicbird (Phaethon aethereus) 3
Brown Boobies (Sula leucogaster) 10
Red-necked Phalarope (Phalaropus lobatus) 1
Pomarine Jaeger (Stercorarius pomarinus) 3
Laughing Gull (Larus atricilla) 100s
Black Tern (Childonias niger) 300
Barn Swallow (Hirundo rustica) 2

Green Sea Turtle (Chelonia mydas) 15

References:

[Austin et al. 2004.  A global molecular phylogeny of the small Puffinus shearwaters and implications for systematics of the Little-Audubon's Shearwater complex.  Auk 121:847-864, b]

Binford, L. C. 1989. A distributional survey of the birds of the Mexican state of Oaxaca. Ornithological Monographs No. 43. AOU.

Harrison, P. 1985. Seabirds: An identification guide. Houghton Mifflin Co. 448p.