Species

Justification
This species is listed as Vulnerable because new analysis suggests that it has a small and severely fragmented range, and the area of suitable habitat is declining. Urban development is the main cause of this decline.

Taxonomic source(s)
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.

Taxonomic note
Ammodramus caudacutus (Sibley and Monroe 1990, 1993) has been split into A. caudacutus and A. nelsoni following AOU (1998).

Identification
13.5 cm. Well-marked and long-billed sparrow. Colourful orange, black and grey head pattern, grey crown and nape, and white streaks on back. Similar spp. Told from close relative Nelson's Sparrow A. nelsoni by its orange malar (brighter than breast), poorly defined white belly and the distinct black streaking on the breast and flanks. Voice Much softer song than A. nelsoni lacking distinctive final note of that species.

Distribution and population
Ammodramus caudacutus is confined to a narrow Atlantic coastal strip of the U.S.A. from Maine southwards to the Delmarva Peninsula, with a southward shift in winter as far as Florida and north to Maryland and Massachusetts (Greenlaw and Woolfenden 2007, J. S. Greenlaw in litt. 2012). It is common to abundant in saltmarshes in the core of its range (J. S. Greenlaw in litt. 2012) and has been estimated to number c.250,000 individuals (Rich et al. 2003, P. Comins in litt. 2003); more recent estimates from Connecticut suggest a figure of c.30,000 individuals is more appropriate (Elphick et al. 2009). Its highly fragmented range is c.20,000 km², within which it occupies an area of less than 2,000 km² of appropriate habitat (P. Comins in litt. 2003, C. Elphick in litt. 2003).

Population justification
Rough extrapolations from more detailed work in Connecticut suggest a global population of c.30,000 individuals, a significantly lower figure than the 250,000 individuals estimated in 2003.

Trend justification
The population is suspected to have declined owing to habitat destruction caused by urban development. Sea-level rises as a result of climate change also threaten the habitat and are a serious potential threat (Greenlaw and Rising 1994, Sibley 1996, C. Elphick in litt. 2003, Bayard and Elphick 2011).

Ecology
Ammodramus caudacutus is found in tidal coastal marshes where there is dense cordgrass, blackgrass or saltmeadow grass. Home ranges preferentially include Spartina patens and Juncus gerardii cover (Shriver et al. 2010), and nesting success is positively correlated with the presence of the latter (Gjerdrum et al. 2008). Nesting takes place from mid May through to early August and males sing occasionally (C. Elphick in litt. 2012) during this time. Nests are placed 6-15 cm above the ground and usually 3-5 greenish white to greenish blue eggs, speckled with reddish brown, are laid. They are not territorial and are not usually found in mixed species flocks (Rising 1996), apart from with A. nelsoni when on migration (J. S. Greenlaw in litt. 2012).

Threats
Localised populations have suffered throughout its range from the historical loss and fragmentation of marshes owing to urban development (Greenlaw and Rising 1994, Sibley 1996, C. Elphick in litt. 2003, 2012). Further on-going threats include degradation from chemical spills and other pollutants, invasive species (particularly Phragmites, which makes the habitat completely unsuitable) and sea level rise (C. Elphick in litt. 2012). The amount by which sea level will rise owing to climate change remains uncertain but Spartina patens dominated marsh (high marsh) may disappear or be greatly reduced in size as the large amount of development along the coast means that there is limited scope for marshes to migrate inland (C. Elphick in litt. 2003). Minimum projections suggest 40-75% of this habitat will be lost (C. Elphick in litt. 2012). In addition, this species appears to be extremely vulnerable to a slight rise in sea-level, when nests are lost due to flooding (Bayard and Elphick 2011). To date the species has not been recorded nesting outside of high marsh habitats; the implications of sea-level rise and loss of high marsh habitats are therefore extremely serious.

Conservation actions underway
A recent project developed population estimates for sites in Connecticut. Using survey data from throughout the species's range this project will estimate the total population size (C. Elphick in litt. 2003). Research into threats to the species, especially the impacts of climate change and sea-level rise is on-going (C. Elphick in litt. 2007), as are developing population and trend estimates, monitoring and habitat management. The species occurs within a number of protected areas supporting coastal habitat, and restoration of tidal marshes is on-going (C. Elphick in litt. 2012).

Conservation actions proposed

References
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Sibley, C. G.; Monroe, B. L. 1993. A supplement to 'Distribution and taxonomy of birds of the world'. Yale University Press, New Haven, USA.

Greenlaw, J. S.; Rising, J. D. 1994. Sharp-tailed Sparrow (Ammodramus caudacutus). In: Poole, A.; Gill, F. (ed.), The birds of North America, No. 112, pp. 1-28. The Academy of Natural Sciences, Philadelphia and The American Ornithologists' Union, Philadelphia and Washington, D.C.

Rising, J. D. 1996. A guide to the identification and natural history of the sparrows of the United States and Canada. Academic Press, London.

Sibley, D. 1996. Field identification of the Sharp-tailed Sparrow complex. Birding 28: 197-208.

AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.

Rich, T.D.; Beardmore, C.J.; Berlanga, H.; Blancher, P.J.; Bradstreet, M.S.W.; Butcher, G.S.; Demarest, D.W.; Dunn, E.H.; Hunter, W.C.; Inigo-Elias, E.E.; Martell, A.M.; Panjabi, A.O.; Pashley, D.N.; Rosenberg, K.V.; Rustay, C.M.; Wendt, J.S.; Will, T.C. 2004. Partners in flight: North American landbird conservation plan. Cornell Lab of Ornithology, Ithaca, NY.

Greenlaw, J. S.; Woolfenden, G. E. 2007. Wintering distributions and migration of Saltmarsh and Nelson's Sharp-tailed Sparrows. Wilson Journal of Ornithology 119(3): 361-377.

Further web sources of information
Auduton WatchList

Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Butchart, S., Khwaja, N., O'Brien, A., Sharpe, C J, Wege, D.

Contributors
Butcher, G., Comins, P., Elphick, C., Greenlaw, J., Rosenberg, K., Wells, J.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Ammodramus caudacutus. Downloaded from http://www.birdlife.org on 21/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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Additional resources for this species

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