Archived 2017 topics: Saltmarsh Sparrow (Ammospiza caudacuta): uplist to Endangered?

BirdLife Species factsheet for Saltmarsh Sparrow:


Saltmarsh Sparrow, Ammospiza caudacuta (formerly Ammodramus caudacutus), is endemic to the Atlantic coast of U.S.A. During the breeding season it is generally found from Maine south to the Delmarva Peninsula, but shifts its range southwards during the winter, and may occur as far south as Florida (Greenlaw and Woolfenden 2007, J. S. Greenlaw in litt. 2012). It inhabits areas of tidal coastal marshes with dense grasses such as blackgrass, cordgrass and saltmeadow grass. It has been proposed that this species occupies only a small area of this habitat (<2,000km2) (P. Comins in litt. 2003, C. Elphick in litt. 2003), and ongoing threats mean that the species is currently listed as Vulnerable under criterion B2ab(i,ii,iii,iv,v) (see BirdLife International 2017).

The most important threat to this species and its habitat has been urban development leading to the loss, degradation and fragmentation of marshes (Greenlaw and Rising 1994, Sibley 1996, C. Elphick in litt. 2003, 2012). Additionally, its habitat has suffered degradation as a result of pollution (e.g. from chemical spills) and invasive species such as Phragmites which make the habitat unsuitable for this species (C. Elphick in litt. 2012). Another important threat, which the species is likely to suffer from even more into the future, is climate change leading to sea-level rises (C. Elphick in litt. 2003, 2012). It is uncertain how much sea-levels will rise within this species’s range, but it is likely that the marshes this species prefers may disappear or be substantially reduced in size (minimum projections of 40-75% lost [C. Elphick in litt. 2012]), as development and habitats/species more resistant to flooding may be preventing the inland migration of tidal marshes (Field et al. 2016, C. Elphick in litt. 2003). However, even given these threats the species probably should not warrant listing as Vulnerable under criterion B2, because it does not meet condition (a) severely fragmented or ≤10 locations. It had been considered to be severely fragmented, but genetics work and the fact it may make seasonal movements mean that there may be some connectivity between areas (albeit potentially limited) (A. Kovach and C. Elphick in litt. 2016).

More up to date population estimates suggest that the species may number 53,000 (37,000-69,000) individuals in the breeding range (Wiest et al. 2016), which would roughly equate to 35,333 (24,667-46,000) mature individuals. Therefore, the species would also not approach the threshold for Vulnerable based on population size. Population trend estimates, however, do imply that the species does warrant remaining as threatened, and indeed would warrant uplisting from Vulnerable to Endangered. Work by Correll et al. (2017) has given an estimated 9.0% annual decline in this species since the 1990s. This equates to a 65.9% decline over 3 generations (11.4 years), and meets the threshold for Endangered. Given that climate change is thought to be able to continue (or increase) these declines into the future it is proposed that this species be listed as Endangered under criteria A2ace+3ce+4ace.

We welcome any comments or further information regarding this proposed uplisting.



BirdLife International. 2017. Species factsheet: Ammospiza caudacuta. Downloaded from on 10/04/2017.

Correll, M. D.; Wiest, W. A.; Hodgman, T. P.; Shriver, W. G.; Elphick, C. S.; McGill, B. J.; O’Brien, K. M.; Olsen, B. J. 2017. Predictors of specialist avifaunal decline in coastal marshes. Conserv. Biol. 31: 172-182.

Field, C. R.; Gjerdrum, C.; Elphick, C. S. 2016. Forest resistance to sea-level rise prevents landwards migration of tidal marsh. Biol. Conserv. 201: 363-369.

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.

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.

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

Wiest, W. A.; Correll, M. D.; Olsen, B. J.; Elphick, C. S.; Hodgman, T. P.; Curson, D. R.; Shriver, W. G. 2016. Population estimates for tidal marsh birds of high conservation concern in northeastern USA from a design-based survey. Condor 118: 274-288.

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3 Responses to Archived 2017 topics: Saltmarsh Sparrow (Ammospiza caudacuta): uplist to Endangered?

  1. Thanks for the opportunity to comment. A couple of months ago, I went through the IUCN criteria in connection with updating the Birds of North America account for the species, and came to exactly the same conclusions as are laid out here; hence, I agree with the proposal.

    Some minor points on the current text, and updated information:
    – Winter range – there is no doubt that the species occurs south to Florida (current wording seems to imply that this is uncertain or that Florida occurrences are rare).
    – Occupied breeding area – we have not recalculated occupied area from our detailed survey data (Wiest et al. 2016), but have modelling products that could be used to obtain a better estimate. I’m not sure this is necessary to the current decision that needs to be done, but if it is then we can try to expedite the work.
    – Pollution – there may have been chemical spills that could affect the species, but I’m not aware of any. The bigger pollution effect is probably nutrient runoff (e.g., fertilizers), which can benefit Phragmites and alter marsh conditions (e.g., Bertness et al. PNAS 99:1395-1398; Deegan et al. 2012. Nature 490:388-392).
    – Marsh loss – there is a fair bit of debate about how much marsh will actually be lost, due to limitations in our understanding of biological feedbacks that could help marshes build as sea-levels rise (e.g., Kirwan et al. Nature Climate Change 6:253-260). But, these discussions tend not to distinguish between the high-elevation marsh areas that saltmarsh sparrows need for nesting and lower elevation areas that are unsuitable. Several recent studies have shown that there are systematic shifts over large areas towards wetter, less suitable, marsh conditions (e.g., Crosby et al. 2016. Estuar. Coast. Shelf Sci. 181:93-99; Field et al. 2016. Biol. Conserv. 201:363-369).
    – Genetics work – several papers on the molecular work are now out (e.g., Walsh et al. 2016 Walsh Biol. J. Linn. Soc. DOI: 10.1111/bij.12837; Walsh et al. 2016 BMC Evol. Biol. 16:65, DOI 10.1186/s12862-016-0635-y; Walsh et al. 2017a Molecular Ecology 26:1242-1255; Walsh et al. 2017b Conservation Genetics 18:453-466), although I’m not sure that they change any of the conclusions made in the assessment.
    – Population estimate – it is not clear to me how the calculation of “mature individuals” was made, though I assume it is some standard discounting formula based on a generic ratio of adults to young (??). The Wiest et al. surveys were timed, however, to largely capture the adult breeding population and probably do not include many young-of-year. A more pertinent correction from a population biology perspective would be to adjust based of sex ratio, which most studies suggest is strongly skewed towards males (at least 60:40 in most studies that have looked). That said, I again don’t think these changes would result in a different conclusion about endangerment status.
    – Trend – in addition to the trend information in Correll et al. there are now also studies that deal with population viability in an explicit way. Field et al. (2017. Global Change Biology 35:2058-2070) takes a highly detailed look at the effects of sea-level rise on demography of the species throughout Long Island Sound and suggests that it is on a trajectory towards extinction by mid-century. Although restricted to just a portion of the species range, there is little reason to believe that the projections are not representative of other areas. In support of this notion, we have a recently accepted paper (which I will send a copy of) that looks at vital rates (and, by extension, population growth) at >20 sites across the species range. This paper shows that projected declines are the norm across study sites. Moreover, the projected decline given the population growth rates estimated from demographic data almost exactly matches the measured 9% decline derived from completely independent survey data.

    If you have questions, or need additional information, please let me know. Links to all of our papers on the species can be found on the SHARP web site, or on my lab site.

  2. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to adopt the proposed classification outlined in the initial forum discussion.

    There is now a period for further comments until the final deadline of 4 August, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Thank you to Dr. Elphick for the detailed information he has provided. I will second his comment that it is likely that the specialized high marsh “salt meadow” habitat that Saltmarsh Sparrows require is likely to be disproportionately affected by sea level rise, but further this species primary problems appear to be related to the intertidal flooding periods between spring tide flooding events on high salt marsh habitats. As such, the productivity rates for Saltmarsh Sparrows can be negatively impacted well before impacts are seen to the habitats itself. That is to say if the neap tide intervals are insufficient, the nests and/or young of the species are likely to drown or suffer from hypothermia from exposure to water and productivity will be diminished and long before any changes to the habitat itself are noted.

    It may also be relevant that the U.S. Fish and Wildlife Service has initiated a Species Status Assessment for Saltmarsh Sparrows for potential listing under the Federal Endangered Species Act as of August 7th, 2017, overseen by Suzanne Paton

    The Connecticut Audubon Society fully supports the proposal to uplist Saltmarsh Sparrows to endangered, particularly in light of the population declines indicated by Correll et al. and Dr. Elphick’s additional reference to Field et al. and the pending accepted paper.

    Thank you for the opportunity to provide comments and for undertaking this status review.



    Patrick M. Comins
    Executive Director, The Connecticut Audubon Society

    314 Unquowa Road
    Fairfield, CT 06824
    203-259-0416 x107

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