Three new species for Aruba , with notes on other significant sightings

A visit to Aruba during April 2013 yielded three species previously unrecorded there: Least Bittern (Ixobrychus exilis), Swainson’s Flycatcher (Myiarchus swainsoni), and Veery (Catharus fuscescens). Seven other species with fewer than five antecedent records from the island were detected plus another not seen since 1980. All documentation and photographs are on file at the University of Amsterdam, Department of Zoology.

This lake provides muddy and grassy edges as well as a strip of Typha marsh.Presumably the level of the lake is dependent on run-off from the golf course and precipitation.Spanish Lagoon is a brackish 1 km cut into the island's interior and is the most prominent mangrove swamp on Aruba.

First Records Least Bittern (Ixobrychus exilis)
On 9 April, I was scanning from the viewing tower at the Bubali Bird Sanctuary and observed two small brown herons standing on water lettuce next to several Green Herons (Butorides virescens) for 5 or more min.I returned the next day and saw one in flight at the same location.These birds were distinctly smaller than their neighboring Green Herons.The sides of their necks, wings, and backs were mostly a deep chestnut buff, brighter and richer than I am used to in North American birds.The back was a very dark orange-buff, while the crown was black.The bill was mostly bright yellowish, but with dark on the culmen.The legs were pale.In flight, the wing coverts appeared more of a yellow buff, contrasting with the dark remiges and orange buff body.This represents the first record from Aruba and the second from the ABC Islands (Prins et al. 2009), which are comprised of Aruba, Bonaire, and Curaçao.The antecedent record is from I explored Aruba from 6 to 12 April 2013, with total birding effort equaling about four full days.During this time, I encountered three species not previously recorded on Aruba, seven species with fewer than five prior Aruban records, and one species unrecorded since 1980.My efforts were concentrated at Bubali Bird Sanctuary, Tierra del Sol Golf Course (TDSGC), and Spanish Lagoon.Bubali Bird Sanctuary and the lake at TDSGC provide the only significant permanent freshwater habitat on this arid island, though several smaller permanent wetlands (e.g., ponds at Divi Divi Golf Course) and intermittent wetlands (e.g., those between Eagle Beach and Malmok) are undoubtedly of importance.Bubali was created in 1972 to handle sewage outflow from the island's resorts and hotels.The resultant marsh is about 1 km long and 0.5 km wide, with most of the area covered by cattails (Typha spp.) and water lettuce (Pistia stratiotes).On the marsh's west shore, there is a line of broadleaf trees with a canopy ranging mostly from 3-6 m in height.The TDSGC lake is Y-shaped and, when full, about 1 km long and 0.25 km wide.
The identification of this species is quite straight forward, but the subspecific identification is not.The two contenders are I. e. exilis, which breeds from North America through most of Central America and in the Caribbean, and I. e. erythromelas, which breeds from Panama through Venezuela and into northern Argentina (Blake 1977) and in Trinidad and Tobago (Buckley et al. 2009).The occurrence of I. e. exilis in Venezuela, as a migrant, is unknown (Hilty 2003).Barbados has two records of Least Bittern, but the subspecies involved remains obscure (Buckley et al. 2009).I. e. erythromelas is reported as being more rufescent on the sides of the neck and tawnier below than I. e. exilis, and my impressions fit I. e. erythromelas more closely, but photographs taken at the same location by Knut Hansen on 18 November 2013 (Hansen 2013) and Mauricio Zanoletti on 10 April 2014 (Zanoletti 2014) seem rather typical for I. e. exilis.One to two birds continued to be seen at the same location through at least 3 May 2014 (G.Peterson in litt).

Swainson's Flycatcher (Myiarchus swainsoni)
While birding the scrubby edges of the TDSGC on 7 April 2013, I encountered a Myiarchus flycatcher (Fig. 1) that was clearly smaller than the resident Brown-crested Flycatcher (M.tyrannulus tyrannulus).Additionally, there was no rufous on the undertail, eliminating Brown-crested Flycatcher and several other Myiarchus flycatchers.The underparts were pale, with the whitish gray throat bleeding into the upper belly, which was buttery yellow.The bill was smaller than that of a Brown-crested Flycatcher, and the mandible had extensive pinkish coloration, which was also present at the base of the maxilla, at least near the cutting edge.The head and auriculars were concolorous, darker than on a Brown-crested Flycatcher, and contrasted fairly sharply with the throat.The back and tail were dull grayish-brown.The wings showed no rufous that I could see, but the tertials were contrast-ingly edged in white or whitish.The bird did not vocalize.It was about 6 m or so away and in excellent light.
The identification of Myiarchus flycatchers is notoriously difficult.Of the Myiarchus that have occurred in nearby Venezuela, only the following lack rust on the undertail: Dusky-capped (M.tuberculifer), Swainson's, Venezuelan (M.venezuelensis), Panama (M.panamensis), Short-crested (M.ferox), and Pale-edged Flycatchers (M.cephalotes).In order to narrow the identification further, Hilty (2003) was consulted, photographs of a selected group of specimens from the Louisiana State University Museum of Zoology (LSUMZ) were reviewed, and photographs on the internet were cautiously inspected.
Of the Myiarchus lacking rust on the tail, only Swainson's and Short-crested Flycatchers can have pale at the base of the bill, a mark far more typical (for some subspecies) of Swainson's Flycatcher.Short-crested Flycatcher was eliminated, as it should appear darker above, brighter below, and with a dusky crown that does not extend below the eyes.The identification search does not end here as vocal, phenotypic, and mtDNA differences suggest that the nominate race of Swainson's Flycatcher may well be a different species than the other subspecies (M.s. phaeonotus, M. s. pelzelni, and M. s. ferocior) currently considered part of M. swainsoni (Joseph et al. 2004).Only the nominate M. s. swainsoni is migratory, and only M. s. swainsoni and the resident M. s. phaeonotus are known to occur in Venezuela (Hilty 2003).The nominate race is the only subspecies described as having extensive pink on the bill, contrasting with M. s. phaeonotus which is described as having an entirely dark bill.The Aruban bird's bill pattern matched well with several photographs taken within the range of M. s. swainsoni (and outside the range of other subspecies), and its overall coloration was a better match for M. s. swainsoni than other subspecies when using the resources mentioned above.
Swainson's Flycatcher has been known to vagrate to Trinidad, with seven specimens collected during July and August 1953 all belonging to M. s. swainsoni (Junge and Mees 1958).The nominate M. s. swainsoni is a fairly common migrant to Venezuela, with known dates of occurrence spanning 26 March and 8 September (Hilty 2003).

Veery (Catharus fuscescens)
On 8 April 2013, a Catharus thrush popped up onto a log at the edge of a rivulet in dense mangroves near Savaneta.Its overall bright rusty upperparts were readily apparent.As I pished, the bird looked over its shoulder, showing a plain gray face without eyering or other markings (e.g., supercilium, transocular stripe).The bird's size was correct for Veery, as was its shape.The back, wings, and tail were uniform in coloration.The bird was seen for approximately 40 s at approximately 7 m.This is a species that the author has considerable experience with from both eastern and western North America.Though this sighting is the first for Aruba, there are five records from Bonaire and four from Curaçao, most of which have been from mid-to late October or from late April into mid-May (Prins et al. 2009).The species is considered uncommon in Venezuela mid-October to mid-April (Hilty 2003).

Additional Records of Note Scarlet Ibis (Eudocimus ruber)
One was photographed at the edge of Bubali Bird Sanctuary on 7 and 9 April 2013 (Fig. 2).This species was regular at Bubali shortly after it was created, but there have been no records from Aruba since 1980 (Prins et al. 2009).Curaçao has one record, from April 2007, and Bonaire lacks any records (Prins et al. 2009).

Long-billed Dowitcher (Limnodromus scolopaceus)
A calling bird was identified at TDSGC on 9 April 2013.It was with a small group of Short-billed Dowitchers (L.griseus), and its longer bill first attracted my attention.However, definitive identification was made only after the bird was heard calling as it flew and circled the pond.Aruba's only prior record was from October 1978.Curaçao has one record, but Bonaire has five or more records, one of up to 50 individuals (Prins et al. 2009).This spe-   cies was unrecorded in Venezuela as of the writing of Hilty (2003) but is listed as a vagrant there by the South American Checklist Committee (Remsen et al. 2015), and there is a specimen record from Colombia (Hellmayr andConover 1948, Naranjo 1991).

Mangrove Cuckoo (Coccyzus minor)
Aruba's second Mangrove Cuckoo was photographed at Spanish Lagoon on 12 April 2013 (Fig. 3).The rarity of this species on Aruba is a bit surprising given that there are greater than five records each for Bonaire and Curaçao (Prins et al. 2009), though it is rare in the mangroves on Venezuela's north coast (Hilty 2003).

Cattle Tyrant (Machetornis rixosa)
Two Cattle Tyrants were found (one photographed) at TDSGC on 9 April 2013 (Fig. 4).It is likely that these are the same two birds reported at TDSGC as early as 29 October 2011 (Peterson 2011) and were still being reported on 6 April 2015 (Cubilla 2015).The ABC Islands' only prior record of Cattle Tyrant comes from Aruba, April 2002 into June 2003 (Prins et al. 2009).This species is common in open and semi-open terrain in northern Venezuela (Hilty 2003).

Magnolia Warbler (Setophaga magnolia)
An alternate male Magnolia Warbler was photographed at Bubali on 10 April 2013 (Fig. 5), furnishing the third record for Aruba; there are also three records from Bonaire and one from Curaçao (Mlodinow 2009, Prins et al. 2009).The only mainland South American records include several from Colombia and one from Venezuelan (Hilty and Brown 1986, Hilty 2003, Remsen et al. 2015).Magnolia Warblers winter predominantly in Mexico and Central American south to Panama and in the Greater Antilles (AOU 1998).

Black-throated Blue Warbler (Setophaga caerulescens)
A female was photographed at Spanish Lagoon on 12 April 2013, furnishing the fourth record for Aruba; Bonaire has five records while there are none for Curaçao (Mlodinow 2006, Prins et al 2009).This species winters mainly in the Bahamas and Greater Antilles (AOU 1998), and there are but three records for Venezuela (Hilty 2003) and two from Trinidad and Tobago (Kenefick et al. 2008).

Palm Warbler (Setophaga palmarum)
An apparent Yellow x Western Palm Warbler intergrade (S. p. hypochrysea x palmarum) was photographed at TDSGC on 7 April 2013 (Fig. 6a).Three additional Palm Warblers, all Western Palm Warblers (S. p. palmarum), were seen and photographed at Spanish Lagoon on 12 April 2013 (Fig. 6b-d).Aruba, Bonaire, and Curaçao each had two antecedent records of this species (Prins et al. 2009), which winters primarily south to Honduras in Middle America and to the Greater Antilles in the West Indies (AOU 1998).Venezuela has but one record (Hilty 2003) and there are none from Trinidad and Tobago (Kenefick et al. 2008).Of the ABC Island records, one was felt to likely be of a Yellow Palm  Warbler (S. p. hypochrysea), but that report is without details (Prins et al. 2009).

Prairie Warbler (Setophaga discolor)
One member of this species was seen at Spanish Lagoon on 8 April 2013.Aruba has two or so prior records, Bonaire none, and Curaçao one (Prins et al 2009).There are no records of this species from Venezuela (Hilty 2003) and but one record from Trinidad and Tobago (Kenefick et al. 2008).

Conclusion
During this visit, I encountered three species previously unrecorded in Aruba, one of which was a first record for Aruba, Bonaire, or Curaçao (Swainson's Flycatcher), one of which represented a second record for these closely grouped islands (Least Bittern), and the third of which must be considered long overdue for Aruba, as it has been recorded multiple times on Bonaire and Curaçao and is an uncommon winter visitor to Venezuela (Veery).Additionally, seven other species were recorded that had been detected fewer than five times on Aruba: five are very rare or casual for South America (Remsen et al. 2015), one is a common resident in Venezuela, and one is a rare resident in Venezuela.Finally, Scarlet Ibis was recorded on Aruba for the first time in 33 yrs, despite being locally common in northern Venezuela.The number of rarities reported here is extensive, yet it is not atypical of visits to Aruba (cf.Mlodinow 2004Mlodinow , 2006Mlodinow , 2009)).See Mlodinow (2009) for a discussion of why Aruba might attract a disproportionate number of vagrants.Future investigations of the island's avifauna are likely to reveal new species records.
All documentation and photographs are on file at the University of Amsterdam, Department of Zoology.

Fig. 1 .
Fig. 1.Swainson's Flycatcher photographed on 7 April 2013 at Tierra Del Sol Golf Course, Aruba.Note the extensive pink on the mandible and pale gray throat (left), the dark extending down through the auriculars (center), and the dull-colored tail (right).The apparent rufescence on the crown is due to sunlight and was not seen in the field.Photographs taken by Steven G. Mlodinow.

Fig. 3 .
Fig. 3. Surprisingly, this Mangrove Cuckoo was only the second ever found on Aruba.Photograph taken at Spanish Lagoon on 12 April 2013 by Steven G. Mlodinow.

Fig. 2 .
Fig. 2.This Scarlet Ibis was the first found on Aruba in 33 yrs.Photograph taken at Bubali Bird Sanctuary on 7 April 2013 by Steven G. Mlodinow.

Fig. 4 .
Fig. 4.This Cattle Tyrant was one of two at Tierra del Sol Golf Course from 29 October 2011 through at least 28 November 2013.Photograph taken by Steven G. Mlodinow on 9 April 2013.

Fig. 6 .
Fig. 6.Four Palm Warblers were seen during April 2013 on Aruba, which had only two prior records.(a) This Palm Warbler, photographed at Tierra del Sol Golf Course on 7 April 2013, is in transitional plumage between basic and alternate.The brilliant yellow extending onto the chest and the relatively sparse and rust colored streaking indicate Yellow Palm Warbler heritage, but the bird overall is too dull, even given its transitional plumage, for a "pure" Yellow Palm Warbler.This mixture of features strongly suggests that it is a Yellow x Western Palm Warbler intergrade.(b-d) Three Western Palm Warblers photographed at Spanish Lagoon on 12 April 2013.Photographs by Steven G. Mlodinow.