MITOCHONDRIAL DNA AND METEOROLOGICAL DATA SUGGEST A CARIBBEAN ORIGIN FOR NEW MEXICO ’ S FIRST SOOTY TERN

We report the first documented record for the sooty tern (Onychop­ rion fuscatus) in new Mexico and the fourth for the region of the southern rocky Mountains and trans-pecos texas. the bird was found dead in moderately fresh condition on 8 July 2010 in the Laguna Grande area, near Carlsbad, eddy County. it was brought to the Museum of southwestern Biology where it was preserved as a study skin. A dnA analysis comparing the sequence of the specimen’s mitochondrial control region to a published population-genetic dataset on this species found that the sequence of the new Mexico tern was a perfect match with previously sequenced haplotypes from puerto rico and Ascension island and ~2% divergent on average from all sooty terns previously sequenced from the pacific and indian oceans. Measurements of the specimen are consistent with a Caribbean origin. We surmise that this individual was carried inland from the Gulf of Mexico to southeastern new Mexico by the remnants of hurricane Alex. the sooty tern (Onychoprion fuscatus) is a seabird that nests on tropical and subtropical islands worldwide (schreiber et al. 2002). Although the species typically remains at sea, it is known to wander widely, often in association with tropical storms (e.g., dickerman et al. 1998, hockey et al. 2005, robin and sudheendra rao 2005). in this paper, we describe a sooty tern specimen that was salvaged far inland in the southwestern united states and that represents one of only a few records for the region. We attempt to identify the natal origins of this specimen by comparing its mitochondrial dnA and measurements to those of sooty terns from potential source populations in the central pacific ocean, the eastern tropical pacific ocean, the Caribbean sea, and the central Atlantic ocean. We also consider weather that may have driven this bird inland. on 8 July 2010, staff of the Mosaic Corporation discovered a dead tern in a brine pond in the Laguna Grande area southeast of Carlsbad, new Mexico. the specimen was transferred to desert Willow Veterinary services where it was tentatively identified as a sooty tern and shipped to the Museum of southwestern Biology (MsB), university of new Mexico. Johnson prepared it as a study skin (MsB 30000; http://arctos.database. museum/guid/MsB:Bird:30000; Figure 1). its identification was confirmed by comparison to another sooty tern skin at MsB. the specimen was received soaked in water and covered with debris but was fresh enough that it could be preserved as a study skin with minimal loss of feathers. its internal anatomy was still intact. its ovary was 8 × 4 mm, with no developing ova, oviduct rather straight, 3 1⁄2 mm wide; the bursa of Fabricius was absent. it was molting primary 3 and rectrices 1 and 6; on the head and neck molt was moderate, on the rest of the body light. its plumage in general was rather worn and faded. Freshly grown feathers on the back were edged in CAriBBeAn oriGin For neW MeXiCo’s First sootY tern 234 white. during preparation, many feathers on the dorsal surface of the base of the neck were lost, resulting in the specimen having a capped appearance, rather than an entirely black dorsum as it originally had. see table 1 for comparison of the specimen’s tarsus, exposed culmen, and wing chord measurements to those of various populations of the sooty tern. in the Atlantic basin the breeding range of the sooty tern comprises coastal islets of the Gulf of Mexico. Although small nesting populations exist in Louisiana and western Florida, the bulk of the population breeds in the Yucatán, and on Caribbean islands from the dry tortugas and the Bahamas through the West indies, Fernando de noronha, Ascension, Martin Vas, and st. helena islands (Aou 1957). in the central and eastern pacific ocean, it breeds from the hawaiian islands to islas revillagigedo and tres Marías along the western coast of Mexico (Aou 1957) and south to subtropical Chilean islands (e.g., easter island; schreiber et al. 2002) . Most authorities recognize seven subspecies of sooty tern, three of which are known from the waters of the united states, Mexico, and Central America (schreiber et Figure 1. photographs of the new Mexico specimen of the sooty tern, MsB 30000; (A) close up of head; (B) ventral view; (C) lateral view; (d) dorsal view. CAriBBeAn oriGin For neW MeXiCo’s First sootY tern 235 Ta bl e 1 C om pa ri so n of M ea su re m en ts o f th e s oo ty a nd B ri dl ed t er ns Lo ca lit y o ce an se x n W in g C ul m en ta rs us so ur ce