||Ammospiza caudacuta (Gmelin, 1788)
||Saltmarsh Sparrow, Saltmarsh Sharp-tailed Sparrow
Ammodramus caudacutus (Gmelin, 1788)
||del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Ammospiza caudacuta (del Hoyo and Collar 2016) was previously placed in the genus Ammodramus and listed as A. caudacutus following AOU (1998 & supplements).
||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.
|Red List Category & Criteria:
||Butcher, G., Comins, P., Elphick, C., Greenlaw, J., Kovach, K., O'Brien, K., Olsen, B., Rosenberg, K., Shriver, G. & Wells, J.
||Benstead, P., Bird, J., Butchart, S., O'Brien, A., Sharpe, C.J., Wege, D., Khwaja, N., Symes, A., Westrip, J.
This species occupies only a small and fragmented range, and new analyses have shown that it is declining at a rapid rate. It has therefore been uplisted to Endangered.
|Previously published Red List assessments:|
- 2016 – Vulnerable (VU)
- 2012 – Vulnerable (VU)
- 2008 – Vulnerable (VU)
- 2004 – Vulnerable (VU)
- 2000 – Lower Risk/near threatened (LR/nt)
- 1994 – Not Recognized (NR)
- 1988 – Not Recognized (NR)
|Range Description:||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 suggest that the species may number 53,000 (37,000-69,000) individuals in the breeding range (Wiest et al. 2016). 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).|
|♦ Estimated area of occupancy (AOO) - km2:||1999||♦ Continuing decline in area of occupancy (AOO):||Yes|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||241000|
|♦ Continuing decline in extent of occurrence (EOO):||Yes||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Continuing decline in number of locations:||Yes|
|♦ Extreme fluctuations in the number of locations:||No|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Recent population estimates suggest that the species may number 53,000 (37,000-69,000) individuals in the breeding range (Wiest et al. 2016). This population estimate was conducted to largely capture the breeding population (C. Elphick in litt. 2017) and so this may actually equate to the number of mature individuals. The sex ratio in this species is approximately 60:40 male:female, and so the number of breeding individuals could have been as low as c.29,600 mature individuals. Therefore, the population size is placed in a range from 29,500-69,000 mature individuals.|
Trend Justification: Correll et al. (2017) estimated that the species has undergone a 9.0% annual decline throughout its range since the 1990s. This equates to a 65.9% decline over 3 generations (11.4 years) (placed here in the range 50-79%), which is considered likely to continue into the future.
|Current Population Trend:||Decreasing|
|♦ Number of mature individuals:||29500-69000||♦ Continuing decline of mature individuals:||Yes|
|♦ Extreme fluctuations:||No||♦ Population severely fragmented:||Yes|
|♦ No. of subpopulations:||2-100||♦ Continuing decline in subpopulations:||Unknown|
|♦ Extreme fluctuations in subpopulations:||No||♦ All individuals in one subpopulation:||No|
|♦ No. of individuals in largest subpopulation:||1-89|
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). Recent population declines are associated with the presence and number of downstream tidal restrictions (levees, roads, train tracks, etc.) that alter natural flow of tide waters in and out of marshes, although the mechanism behind this link is not well known (Correll et al. 2017). Further on-going threats include increased tidal flooding (e.g., due to sea level rise and increased storm surge frequency/magnitude), hybridization with Nelson’s Sparrows A. nelsoni (which may reduce fitness and limit the number of pure Saltmarsh Sparrow populations), degradation from chemical spills and other pollutants, and invasive species (particularly Phragmites, which makes the habitat completely unsuitable) (C. Elphick in litt. 2016).
This species appears to be extremely vulnerable to a slight rise in sea-level, as nests are lost due to flooding (Bayard and Elphick 2011, Shriver et al. 2016, Field et al. 2017a). 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, with the potential for the species to go extinct in the near future (see Field et al. 2017a). 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; and vegetation within marshes is already changing in a manner that suggests marshes are getting wetter (Field et al. 2016).