Golden swallow (bird)
| Golden Swallow | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Hirundinidae |
| Genus: | Tachycineta |
| Species: | T. euchrysea |
| Binomial name | |
| Tachycineta euchrysea (Gosse, 1847, higher mountains in the centre of Jamaica) | |
The golden swallow (Tachycineta euchrysea) is an aerial insectivore and obligate secondary cavity nester endemic to the Caribbean islands of Jamaica and Hispaniola. The declining Hispaniolan subspecies (T. e. sclateri) is estimated at 1500 – 7000 individuals and the population is categorized as vulnerable by the International Union for Conservation of Nature. The nominate race on Jamaica (T. e. euchrysea) has not been unequivocally observed since the early 1980s. Extensive surveys targeting the subspecies were conducted between 1994 and 2015. No golden swallows were observed. Despite the infinitesimal probability that a relict population persists undetected, there is strong evidence that the Jamaican Golden Swallow is extinct.
Hispaniolan subspecies
The Hispaniolan Golden Swallow (Tachycineta euchrysea sclateri) is believed to be endemic to the island of Hispaniola (Latta et al. 2006). The most recent estimates generated in 2000 (IUCN data quality: poor) gauge population size at anywhere from 1500-7000 mature individuals with a declining trend. This assessment justifies placement of the species into “Vulnerable, Category B” (small range and fragmented, declining or fluctuating) on the IUCN Red List of Threatened Species (BirdLife International 2012). From the earliest known records to today’s most current sightings, the swallow has been described as a bird of the mountains (Cory 1884, 1886, Bond 1928, 1936, 1943, Wetmore and Swales 1931, Raffaele 1998, Latta et al. 2006, eBird 2015).
Wetmore and Swales (1931:315-316): “This handsome swallow is found among the interior hills and is greeted with delight wherever seen from its graceful actions and pleasing coloration. As one climbs over steep slopes in the mountains among dead trunks of pine a long-tailed swallow may come circling through the air to display in passing a white breast and glossy back. In its active evolutions it is certain to attract the eye and the traveler is sure to pause to observe its course as it circles quickly away.”
At present, the species is found in the Sierra de Neiba (highest point: Pico Neiba – 2,279 m), Cordillera Central (Pico Duarte – 3,098 m) and Sierra de Bahoruco (Loma Gaio en Medio – 1,779 m) mountain chains of the Dominican Republic (Turner and Rose 1989, Dod 1992, Klein et al. 1998, Fernandez and Keith 2003, Rimmer et al. 2004, Townsend 2006, Townsend et al. 2008) and within the Massif du Nord (near Morne Beaubrun – 1,160 m), Massif de la Hotte (Pic de Macaya – 2,347 m), Montagnes Noires (near Morne Boeuf – 1,760 m) and Massif de la Selle (Pic la Selle – 2,680 m) of Haiti (Bond 1928, Woods and Ottenwalder 1986, Raffaele et al. 1998, Dávalos and Brooks 2001, Keith et al. 2003, Rimmer et al. 2005, 2010) (Fig. 1).
Throughout its range, the swallow is thought to be increasingly restricted to isolated remnant patches of montane forest dominated by Hispaniolan pine (Pinus occidentalis) (Keith et al. 2003, Latta et al. 2006, Townsend et al. 2008), a trend that is congruent with a notable decrease in the species’ presence at lower elevations over the last century (Wetmore and Swales 1931, Latta et al. 2006, eBird 2015). The species is believed to have declined over the past several decades (Dod 1992, Keith 2003, BirdLife International 2015); though some localized populations may have recently stabilized (Rimmer 2004). Some authors attribute the decline to habitat loss and degradation within native pine forests (Keith 2003) - a concern echoed by scientists studying the congener T. cyaneoviridis in the Bahamas (Allen 1996). Others have highlighted high rates of nest depredation by invasive mammals including the small Indian mongoose (Herpestes auropunctatus; additional common names: small Asian mongoose, Javan mongoose, marsh mongoose) (Hays and Conant 2007, Veron et al. 2007) and black rat (Rattus rattus) (Townsend 2006). Though the underlying causes are not definitive, the species’ increasing sparsity over its historical range has been the catalyst for the scientific community’s growing advocacy towards implementing conservation measures (Rimmer et al. 2005, Townsend et al. 2008).
Researchers have been studying the life history and breeding biology of the Hispaniolan subspecies since 2012 through the use of artificial nest boxes in Parque Valle Nuevo, Dominican Republic. Initial conservation efforts are currently underway (Proctor et al. in review).
Jamaican subspecies:
The Jamaican Golden Swallow (Tachycineta euchrysea euchrysea) was known only from Jamaica since its description by the naturalist Philip Henry Gosse (Gosse 1847). Although always considered uncommon and locally distributed (Graves 2014), the Jamaican Golden Swallow showed noticeable signs of decline by the mid-20th century (Kidd 1964, 1965, Downer and Sutton 1972, Lack 1976) and disappeared altogether by the mid-1980s (Downer 1982, Graves 2014). What would become the last unequivocal sighting occurred on 11 September 1982, prompting a concerned communication by the local ornithologist Audrey Downer (Downer 1982:32):
“Is The Golden Swallow Declining?: In 1858 Osburn wrote to Gosse … describing Golden Swallows as appearing ‘in great numbers’ over the canefields of Trelawny. Several years ago when Robert Sutton and I saw them at Ram Goat Cave there were only 5 or 6 seen at a time. No report has recently been recorded in the Broadsheet, but some visitors to the island in August this year [1982] reported seeing them on the Barbecue Bottom Road. In order to verify this report, a group of us headed by Robert Sutton went along this same road in the Cockpit Country on Sept. 11th, 1982. After stopping at Ram Goat Cave and Barbeque Bottom where we heard swallows but saw only Cave [Swallows] and [Antillean] Palm Swifts we stopped between the 15th and 14th mile-post at a spot overlooking the ruins of Stonehenge. Immediately below us was a grassy area with canefields in the distance. This looked like the spot described by the visitors, and sure enough Robert soon spotted a Golden Swallow circling with Cave Swallows … The visitors reported seeing 7 Golden Swallows, and we saw between 6 and 9 at a time. This is a far cry from the numbers reported by Osburn. Are they declining or are they more numerous after a rainy spell?”
More than 25 years have passed since the last confirmed sighting of the Jamaican subspecies. Since then, there have been no sightings by investigators specifically targeting the subspecies (Graves 2014, Proctor et al. in review) nor any reports from local or international birdwatchers. Furthermore, there is no evidence that either Golden Swallow subspecies has ever migrated off-island. Despite the extremely minute probability that a remaining population continues to persist undetected, at this point it should be confidently declared that the Jamaican Golden Swallow is extinct.
References
- ↑ BirdLife International (2012). "Tachycineta euchrysea". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. Retrieved 16 July 2012.