Demography and Populations

Demographic rates vary substantially across the range in relation to migratory status, habitat quality, and environmental factors like the timing of disturbance (e.g., fire, precipitation). Predation and flooding are major causes of nest failure throughout the range and the influence of these two factors varies locally by site and regionally by latitude. The global population based on the North American Breeding Bird Survey (BBS) was estimated to be 200,000 individuals (95% CI: 32,000, 520,000) from 2006–2015 (216 Partners in Flight (2020). Population Estimates Database, version 3.1. Close ); however, the population estimate for the northeastern United States (Virginia to Maine) was 234,000 (112,000, 356,000) from 2011–2012 (217 Wiest, W. A., M. D. Correll, B. G. Marcot, B. J. Olsen, C. S. Elphick, T. P. Hodgman, G. R. Guntenspergen, and W. G. Shriver (2019). Estimates of tidal-marsh bird densities using Bayesian networks. Journal of Wildlife Management 83(1):109–120. Close ), suggesting that the global estimate could be closer to 500,000.

Age at First Breeding

Both sexes begin breeding spring after hatching year.

Clutch

Clutch size ranges from 2 to 5 eggs. Modal clutch in northeastern salt marsh populations (A. m. maritima) is 4 eggs. More southerly salt-marsh groups have modal clutch of 3 eggs. Mean clutch size: New York, 3.66 ± 0.59 SD (range 2–5, n = 272); South Atlantic group (North Carolina to Florida), 3.06 ± 0.49 SD (range 2–5, n = 100) (Charleston Museum); northern Florida (A. m. peninsulae), 3.08 ± 0.31 SD (range 2–4, n = 108) (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ). East-central Florida (A. m. nigrescens), 3.60 ± 0.53 SD (range 2–4, n = 91) (Clemson University, Western Foundation Vertebrate Zoology); Florida Everglades (A. m. mirabilis) based on initial small sample size, 3.53 ± 0.70 SD (range 2–4, n = 19) (180 Stimson, L. A. (1968). Ammospiza mirabilis (Howell). Cape Sable Sparrow. In Life Histories of North American Cardinals, Grosbeaks, Buntings, Towhees, Finches, Sparrows, and Allies (O. L. Austin Jr., Editor) U.S. National Museum Bulletin No. 237, part 2. pp. 859–868. Close , 161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ), but average clutch size based on subsequent large sample sizes (n = 160, 175) were 3.1 ± 0.80 SD and 3.4 ± 0.66 SD (9 Pimm, S. L., J. L. Lockwood, C. N. Jenkins, J. L. Curnutt, M. P. Nott, R. D. Powell, and O. L. Bass Jr. (2002). Sparrow in the grass. A report on the first ten years of research on the Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis). Report to the National Park Service, Everglades National Park, FL, USA. Close , 197 Boulton, R. L., B. Baiser, M. J. Davis, T. Virzi, and J. L. Lockwood (2011). Variation in laying date and clutch size: the Everglades environment and the endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis). Auk 128(2):374–381. Close ).

As with other saltmarsh-breeding sparrows, though clutch size varies with latitude, predation pressure may be a more important factor in explaining differences in clutch size among populations—within the former Ammodramus, there is a significant negative relationship between clutch size and predation rates. No relationship to loss due to flooding (134 Greenberg, R., C. S. Elphick, J. C. Nordby, C. Gjerdrum, H. Spautz, G. Shriver, B. Schmeling, B. Olsen, P. Marra, N. Nur, and M. Winter (2006). Flooding and predation: Trade-offs in the nesting ecology of tidal-marsh sparrows. Studies in Avian Biology (32):96–109. Close ).

Annual and Lifetime Reproductive Success

Period nest survival varies among sites, years, and in response to disturbance ranging from 0.013 to 0.530 (Table 3). Lowest period nest survival estimates were documented in Georgia (201 Hunter, E. A., N. P. Nibbelink, and R. J. Cooper (2016). Threat predictability influences Seaside Sparrow nest site selection when facing trade-offs from predation and flooding. Animal Behaviour 120:135–142. Close ) and Maryland (218 Kern, R. A., and W. G. Shriver (2014). Sea level rise and prescribed fire management: Implications for seaside sparrow population viability. Biological Conservation 173:24–31. Close ). In Georgia, there seems to be a clear tradeoff between the competing risks of nest failure caused by flooding vs. predation and the strength of these risks varies annually (201 Hunter, E. A., N. P. Nibbelink, and R. J. Cooper (2016). Threat predictability influences Seaside Sparrow nest site selection when facing trade-offs from predation and flooding. Animal Behaviour 120:135–142. Close ). In Maryland, extremely high precipitation events occurring in May and June caused nearly catastrophic nest flooding leading to low estimates of nest survival (218 Kern, R. A., and W. G. Shriver (2014). Sea level rise and prescribed fire management: Implications for seaside sparrow population viability. Biological Conservation 173:24–31. Close ). Substantial research has been conducted on the patterns in nest survival for Cape Sable Seaside sparrow indicating variation within the subpopulations as well as in response to fire (8 Lockwood, J. L., K. H. Fenn, J. L. Curnutt, D. Rosenthal, K. L. Balent, and A. L. Mayer (1997). Life history of the endangered Cape Sable Seaside Sparrow. Wilson Bulletin 109(4):720–731. Close , 135 Lockwood, J. L., K. H. Fenn, J. M. Caudill, D. Okines, O. L. Bass, J. R. Duncan, and S. L. Pimm (2001). The implications of Cape Sable Seaside Sparrow demography for Everglades restoration. Animal Conservation 4:275–281. Close , 219 La Puma, D. A., J. L. Lockwood, and M. J. Davis (2007). Endangered species management requires a new look at the benefit of fire: The Cape Sable Seaside Sparrow in the Everglades ecosystem. Biological Conservation 136:398–407. Close , 198 Baiser, B., R. L. Boulton, and J. L. Lockwood (2008). Influence of water depth on nest success of the endangered Cape Sable Seaside Sparrow in the Florida Everglades. Animal Conservation 11(3):190–197. Close ).

Mean number of young fledged per female each year: Massachusetts: 3.97 (range 3.46–4.47, n = 2 yr) (117 Marshall, R. M., and S. E. Reinert (1990). Breeding ecology of Seaside Sparrows in a Massachusetts salt marsh. Wilson Bulletin 102(3):501–513. Close ); New York: 4.43 (range 3.38–5.77, n = 4 yr) (163 Post, W., and J. S. Greenlaw (1982). Comparative costs of promiscuity and monogamy - a test of reproductive effort theory. Behavioral Ecology and Sociobiology 10(2):101–107. Close ); New Jersey from 2011–2015: 2.65 (95% CI:2.21–3.09; 220 Roberts, S. G. (2016). Population viability of Seaside and Saltmarsh sparrows in New Jersey. Ph.D. dissertation, Newark, DE, USA. Close ); South Carolina: 2.50; Georgia: 1.90; Florida: 2.47 (67 U.S. Fish and Wildlife Service (2018). Species status assessment report for the MacGillivray's Seaside Sparrow (Ammodramus maritimus macgillivraii). Version 1.3. U.S. Fish and Wildlife Service, Region 4, Athens, GA, USA. Close ) and 0.58 (range 0.17–0.99, n = 2 yr) (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ).

Estimated lifetime reproductive output of average female (productivity discounted by survival = estimated replacement rate): 2.72 in New York, and 1.11 Gulf Hammock, Florida (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ).

Life Span

Potential life span of males and females of several populations was reported as 8–9 years (138 Sykes, P. W., Jr. (1980). Decline and disappearance of the Dusky Seaside Sparrow from Merritt Island, Florida. American Birds 34:728–737. Close ; M. V. McDonald, personal communication; WP). The oldest known individual was a male banded as an adult in South Carolina in 2005 and recaptured there in 2014 at a minimum of 10 years of age (221 Bird Banding Laboratory (2019). Longevity records of North American birds. Version 2019.2. Patuxent Wildlife Research Center, U.S. Geological Survey, Laurel, MD, USA. Close ).

Survival

Survival rates for migratory (maritima) and resident subspecies are provided below; information is limited regarding survival to first year of independence.

A. m. maritima. Minimum annual survival of breeding adults (based on cumulative return rates): 1967–1972 year classes, calculated through 1980: females 60.4% (n = 169); males: 57.0% (n = 214); 1976–1977 year classes, through 1980: females, 41.4% (n = 58); males, 52.8% (n = 269). Survival of juveniles was lower, or dispersal greater, than in nonmigratory groups. Survival from fledging to independence (from departing nest to no longer being brooded by adults): New York, 36% (n = 126) (163 Post, W., and J. S. Greenlaw (1982). Comparative costs of promiscuity and monogamy - a test of reproductive effort theory. Behavioral Ecology and Sociobiology 10(2):101–107. Close ). In Massachusetts, none of 35 nestlings banded in 1985 were seen the following year. In Connecticut, apparent adult survival was 72.0–89.6% (110 Borowske, A. C. (2015). Effects of life history strategies on annual events and processes in the lives of tidal marsh sparrows. Ph.D. dissertation, University of Connecticut, Storrs, CT, USA. Close ). In New Jersey, apparent adult survival was 61.6% (95% CI: 52.5, 70.0) (5 Roberts, S. G., R. A. Longenecker, M. A. Etterson, K. J. Ruskin, C. S. Elphick, B. J. Olsen, and W. G. Shriver (2017). Factors that influence vital rates of Seaside and Saltmarsh sparrows in coastal New Jersey, USA. Journal of Field Ornithology 88(2):115–131. Close ). During five nonbreeding periods (2006–2010) in North Carolina, apparent adult survival was 48.3% (142 Winder, V. L., A. K. Michaelis, and S. D. Emslie (2012). Winter survivorship and site fidelity of Nelson's, Saltmarsh, and Seaside sparrows in North Carolina. Condor 114:421–429. Close ).

A. m. macgillivraii. Minimum survival rates in South Carolina (lower 95% confidence limit, based on mark-recapture; WP, unpublished data). For nestlings (n = 99, marked 1999–2003): survival to independence, 30%. Juveniles (n = 85, marked in 2000): hatch year (from independence)–year 1, 10.4%; year 1–2, 97.6%; year 2–3, 19.1%; year 3–4, 11.0%; and year 5–6, 8.8%. Adult males (n = 154, marked in 2000): year 1–2, 72%; year 2–3, 58%, year 3–4, 53%; year 4–5, 32%. Adult females (n = 66, marked in 2000): year 1–2, 52%; year 2–3, 18%; year 3–4, 38%; year 4–5, 14%.

A. m. peninsulae. Minimum annual survival of adult males in northern Florida was 85.7% (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ).

A. m. mirabilis. Annual adult survival for Cape Sable Seaside Sparrow was estimated as high as 88% in the 1970s (161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ), 63–69% (19 adults, 1997–1998; 131 Dean, T. F., and J. L. Morrison (1998). Non-breeding season ecology of the Cape Sable Seaside Sparrow. In 1997–1998 field season final report. Everglades National Park, Homestead, FL, USA. Close ), 66% (265 adults, 1994–1998; 135 Lockwood, J. L., K. H. Fenn, J. M. Caudill, D. Okines, O. L. Bass, J. R. Duncan, and S. L. Pimm (2001). The implications of Cape Sable Seaside Sparrow demography for Everglades restoration. Animal Conservation 4:275–281. Close ) in the 1990’s, and more recently, 60% (93 adults from population E, 2002–2007 (222 Boulton, R. L., J. L. Lockwood, M. J. Davis, A. Pedziwilk, K. A. Boadway, J. J. T. Boadway, D. Okines, and S. L. Pimm (2009). Endangered Cape Sable Seaside Sparrow survival. Journal of Wildlife Management 73(4):530–537. Close ). Boulton et al. (222 Boulton, R. L., J. L. Lockwood, M. J. Davis, A. Pedziwilk, K. A. Boadway, J. J. T. Boadway, D. Okines, and S. L. Pimm (2009). Endangered Cape Sable Seaside Sparrow survival. Journal of Wildlife Management 73(4):530–537. Close ) captured 498 juveniles (96% captured as nestlings and 4% captured as fledglings) from 1998–2007 and estimates of juvenile survival rate ranged from 9% in 2000 to 47% in 2002. Sexes of mirabilis have similar return rates: males: 26–52%; females, 25–45%. Return rate for juveniles 13%. No information on first-year survival, as no banded nestlings were recaptured in same year (135 Lockwood, J. L., K. H. Fenn, J. M. Caudill, D. Okines, O. L. Bass, J. R. Duncan, and S. L. Pimm (2001). The implications of Cape Sable Seaside Sparrow demography for Everglades restoration. Animal Conservation 4:275–281. Close ).

Body Parasites

Of 206 adults examined in New York, 60% had feather lice (Mallophaga; Philopterus subflavescens); males were infested more often than females (37 Post, W., and F. Enders (1970). The occurrence of Mallophaga on two bird species occupying the same habitat. Ibis 112:539–540. Close ). Soft ticks (Argasidae; Haemaphysalis chordeilis) were found on 2 of 206 birds (WP; 223 Peters, H. S. (1936). A list of external parasites from birds of the eastern part of the United States. Bird-Banding 7:9–27. Close ). Avian louse flies (Hippoboscidae) were noted on 1 of about 500 birds examined in New York (WP).

Individuals in North Carolina were often infected with helminths; only 2 of 100 examined were worm-free (224 Hunter, W. S., and T. L. Quay (1953). An ecological study of the helminth fauna of Macgillivray's Seaside Sparrow, Ammospiza maritima macgillivraii (Audubon). American Midland Naturalist 50:407–413. Close ). Infected birds had 9 species of trematodes (42% infection rate), 3 species of cestodes (51%), 2 species of Acanthocephala (83%), and 7 species of nematodes (59%). Only one species of nematode (Microtetrameres cruzi) produced visible pathogenic effects: proventricular walls of 3 hosts were damaged (224 Hunter, W. S., and T. L. Quay (1953). An ecological study of the helminth fauna of Macgillivray's Seaside Sparrow, Ammospiza maritima macgillivraii (Audubon). American Midland Naturalist 50:407–413. Close ).

Fowl pox has rarely been reported; only 2 of about 500 adults examined at Oak Beach, New York (1976–1978) had obvious lesions (WP).

Daily nest mortality rates in northern Florida were 19.4%, versus 3.3% in New York (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ). In New York and Massachusetts, the primary known mortality factor for nest contents in some years was storm-related flooding (New York: 24% of lost eggs, 38% of lost young [3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ]; Massachusetts: 89% of nests [117 Marshall, R. M., and S. E. Reinert (1990). Breeding ecology of Seaside Sparrows in a Massachusetts salt marsh. Wilson Bulletin 102(3):501–513. Close ]). The main known cause of nest failure in northern Florida was assumed to be predation by marsh rice rat (Oryzomys palustris) and Fish Crow (Corvus ossifragus) which accounted for 28% and 12% of losses, respectively (119 Post, W. (1981). The influence of rice rats Oryzomys palustris on the habitat use of the Seaside Sparrow Ammospiza maritima. Behavioral Ecology and Sociobiology 9:35–40. Close ). Predation was also a major source of nest mortality in New York (40.9% of total eggs lost, 63.1% of total young lost) and New Jersey (220 Roberts, S. G. (2016). Population viability of Seaside and Saltmarsh sparrows in New Jersey. Ph.D. dissertation, Newark, DE, USA. Close , 5 Roberts, S. G., R. A. Longenecker, M. A. Etterson, K. J. Ruskin, C. S. Elphick, B. J. Olsen, and W. G. Shriver (2017). Factors that influence vital rates of Seaside and Saltmarsh sparrows in coastal New Jersey, USA. Journal of Field Ornithology 88(2):115–131. Close ). In New York, hatching failure accounted for 11.3% of egg mortality. In Florida Everglades, early season nests were more successful than those initiated later. Seasonal effect due to changes in predator abundance, which was related to increased water levels at onset of wet season (198 Baiser, B., R. L. Boulton, and J. L. Lockwood (2008). Influence of water depth on nest success of the endangered Cape Sable Seaside Sparrow in the Florida Everglades. Animal Conservation 11(3):190–197. Close ); 41% of eggs laid from March to early June produced fledglings (30% of mortality due to predation); value dropped to 13% for late-season nests, (67% of nests depredated) (135 Lockwood, J. L., K. H. Fenn, J. M. Caudill, D. Okines, O. L. Bass, J. R. Duncan, and S. L. Pimm (2001). The implications of Cape Sable Seaside Sparrow demography for Everglades restoration. Animal Conservation 4:275–281. Close ).

Little information on mortality factors of independent birds. Although nests always vulnerable, fires with multiple ignition points (usually human-caused) may also kill adults and fledglings (7 Werner, H. W., and G. E. Woolfenden (1983). The Cape Sable Sparrow: its habitat, habits, and history. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 55–75. Close ). During an Everglades fire, Werner (161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ) saw sparrows fly to adjacent unburned areas, and circle in areas of smoke and flames. After a fire in 1975 that burned 850 hectares of A. m. nigrescens habitat on St. Johns River, Florida, only 7 of 36 banded males could be relocated (225 Walters, M. J. (1992). A shadow and a song. Chelsea Green Publishing Co., Post Hills, VT, USA. Close )

Storms may have little direct effect on adult survival. Population at Cape Sable, Florida (A. m. mirabilis) survived September 1935 hurricane, which had winds of 220 km/h (226 Semple, J. B. (1936). The Cape Sable Sparrow and hurricanes. Auk 53:341. Close ). Between 1871 and 1973, 8 hurricanes passed over Cape Sable, but apparently did not affect sparrows in that area (161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ). The hurricane of August 1992, however, was estimated by Pimm et al. (227 Pimm, S. L., G. E. Davis, L. Loope, C. T. Roman, T. J. Smith, and J. T. Tilmant (1994). Hurricane Andrew. BioScience 44(4):224–229. Close ) to have reduced the mirabilis population from 6,000 to 4,000 (but see Curnutt et al. [139 Curnutt, J. L., A. L. Mayer, T. M. Brooks, L. Manne, O. L. Bass, D. M. Fleming, M. P. Nott, and S. L. Pimm (1998). Population dynamics of the endangered Cape Sable Seaside Sparrow. Animal Conservation 1(1):11–21. Close ]).

After severe storm in April 1993 over Grande Isle, Louisiana, 3 Seaside Sparrows were found washed up during search of 30 km of shoreline; it was estimated, by extrapolation, that a total of 111 Seaside Sparrows had been killed in the storm (228 Wiedenfeld, D. A., and M. G. Wiedenfeld (1995). Large kill of Neotropical migrants by tornado and storm in Louisiana, April 1993. Journal of Field Ornithology 66:70–80. Close ), but this number seems improbable, as it was based on the assumption that Seaside Sparrow is a trans-Gulf migrant.

Individual Distance

In breeding period, physical contact occurs between fighting individuals. During mutual displays such as bobbing and wing-raising, neighboring males may approach within 20 cm of each other (169 Post, W., and J. S. Greenlaw (1975). Seaside Sparrow displays: their function in social organization and habitat. Auk 92:461–492. Close ). At distances < 10 cm, fighting usually ensues. Nearest individual distances among captives 3–5 cm. No contact during roosting. In one instance, male attempted 6 times to preen another in head and shoulder region; each attempt was repulsed (WP). During February flood tides in Georgia, 228 Seaside Sparrows and 8 "sharp-tailed sparrows" [Ed: potentially both Saltmarsh Sparrow (Ammospiza caudacuta) and Nelson's Sparrow (Ammospiza nelsoni)] congregated on an 8 m² grass island. Many birds were in contact, some “practically climbing on each others' shoulders in an attempt to find a perch (192 Beaton, G. (1993). Effects of unusually high tides on some coastal species or does anyone have an ark? Oriole 58(1–4):22–23. Close ).

Territory Size

Mean territory size: Buzzard's Bay, Massachusetts: 3,953 m² (range 1,290–10,423, n = 17) (117 Marshall, R. M., and S. E. Reinert (1990). Breeding ecology of Seaside Sparrows in a Massachusetts salt marsh. Wilson Bulletin 102(3):501–513. Close ); Narragansett Bay, Rhode Island: 4,545 m² (range 944–8,837, n = 18) (176 DeRagon, W. R. (1988). Breeding ecology of Seaside and Sharp-tailed sparrows in Rhode Island salt marshes. M.S. thesis, University of Rhode Island, Kingston, RI, USA. Close ); Oak Beach, New York: 1,203 m² (range 160–6,190, n = 25) (169 Post, W., and J. S. Greenlaw (1975). Seaside Sparrow displays: their function in social organization and habitat. Auk 92:461–492. Close ); Tobay, New York: 8,781 m² (range 810–17,640, n = 13) (116 Post, W. (1974). Functional analysis of space-related behavior in the Seaside Sparrow. Ecology 55:564–575. Close ); Gulf Hammock, Florida: 1,600 m² (range 200–3,200, n = 37) (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ); Taylor Slough, Florida: 15,000 m² (range 3,000–66,000, n = 43) (161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ); Ochopee, Florida: 36,000 m² (range 7,000–8,000, n = 10) (7 Werner, H. W., and G. E. Woolfenden (1983). The Cape Sable Sparrow: its habitat, habits, and history. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 55–75. Close ); St. Johns, Florida: 5,100 m² (range 1,600–10,060, n = 14) (183 Baker, J. L. (1973). Preliminary studies of the Dusky Seaside Sparrow on the St. Johns National Wildlife Refuge. Proceedings Southeastern Association Game and Fish Commissioners 27:207–214. Close ).

Home Range Size

Activity space (home range) sizes vary among regions, habitats, and seasons; most differences appear to be attributable to variation in habitat quality (229 Greenlaw, J. S., and W. Post (1985). Evolution of monogamy in Seaside Sparrows, Ammodramus maritimus: test of hypotheses. Animal Behavior 33(2):373–383. Close ). Because adults often forage away from nest site, total activity space usually larger than territory (defended space). In an unaltered marsh (New York), mean foraging space was 1,039 m² (range 170–5,135, n = 21). Area in which singing occurred was 47% size of foraging area; defended area was 38% of foraging area. In ditched marsh (New York), mean foraging space was 8,121 m² (range 11,520–17,510). Singing area was 58%, and defended area was 40%, of foraging space (116 Post, W. (1974). Functional analysis of space-related behavior in the Seaside Sparrow. Ecology 55:564–575. Close ). In Delaware, territory density was over two times greater on marshes with limited Open Marsh Water Management (OMWM; 5.35 ± 0.60 territories/ha) than on marshes with extensive OMWM (2.39 ± 0.56 territories/ha; 4 Pepper, M. A., and W. G. Shriver (2010). Effects of Open Marsh Water Management on the reproductive success and nesting ecology of Seaside Sparrows in tidal marshes. Waterbirds 33:381–388. Close ).

Cape Sable Seaside Sparrow (A. m. mirabilis) is relatively sedentary in nonbreeding period; winter home ranges, which often overlapped for adjacent males, averaged 12 ha. The movements of several radio-tagged birds were > 3 km; the longest was 7 km (131 Dean, T. F., and J. L. Morrison (1998). Non-breeding season ecology of the Cape Sable Seaside Sparrow. In 1997–1998 field season final report. Everglades National Park, Homestead, FL, USA. Close ). Winter home ranges of mirabilis did not shift with changes in water depth; when water rose, sparrows occupied parts of home range that had fewer openings and higher vegetation such as sawgrass.

Numbers

Population Size

Using data from the North American Breeding Bird Survey (BBS), the global Seaside Sparrow population was estimated at 200,000 individuals (95% CI: 32,000, 520,000) from 2006–2015 (216 Partners in Flight (2020). Population Estimates Database, version 3.1. Close ).

Wiest et al. (217 Wiest, W. A., M. D. Correll, B. G. Marcot, B. J. Olsen, C. S. Elphick, T. P. Hodgman, G. R. Guntenspergen, and W. G. Shriver (2019). Estimates of tidal-marsh bird densities using Bayesian networks. Journal of Wildlife Management 83(1):109–120. Close ) estimated 234,000 individuals (range 112,000–356,000) for subspecies A. m. maritima from Virginia to the northern extent of the breeding range from 2011–2012. The population size of A. m. macgillivraii was estimated at 32,800 individuals occurring along 100 miles of coastline and divided into four breeding populations with three in South Carolina (North Inlet–Bulls Island, Headquarters Island, and ACE Basin) and one population in Georgia–Florida (67 U.S. Fish and Wildlife Service (2018). Species status assessment report for the MacGillivray's Seaside Sparrow (Ammodramus maritimus macgillivraii). Version 1.3. U.S. Fish and Wildlife Service, Region 4, Athens, GA, USA. Close ). Seaside Sparrow has been extirpated from the Atlantic coast of Florida south of Duval County (northeastern Florida), and other than A. m. peninsulae, most Florida populations are small and disjunct (49 Kale, H. W., II (1983). Distribution, habitat, and status of breeding Seaside Sparrows in Florida. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 41–48. Close ). In 1988, the population on northwestern Gulf of Mexico (peninsulae) was estimated to contain 5,000–10,000 birds (24 McDonald, M. V. (1988). Status survey of two Florida Seaside Sparrows and taxonomic review of the Seaside Sparrow assemblage. Florida Cooperative Fish and Wildlife Research Unit, University of Forida, Gainesville, FL, USA. Close ).

A. m. mirabilis occupies much of its historical range. As of 1982, it was widely distributed over 27,800 ha of southern Florida west and east of Shark River Slough, but became rare or absent from Cape Sable and Ochopee areas as the habitat was altered (shrub invasion, hurricane effects). The main population is in or near Taylor Slough, and in 1992 included at least 6,640 birds. Only about 3,700 birds present in 1993 after Hurricane Andrew (J. Curnutt, personal communication); in 2007 the population was estimated at 3,184 birds in 5 separate groups. The largest group, “population B,” had about 2,512 pairs (140 Pimm, S. L., C. N. Jenkins, and S. Bass (2007). Cape Sable Sparrow annual report 2007. Everglades National Park, Homestead, FL, USA. Close ).

Historically, A. m. nigrescens had a very limited distribution in east-central Florida (Merritt Island and adjacent St. Johns River marshes). In 1968, an estimated 900 males, and presumably equal number of females, remained (230 Sharp, B. (1970). A population estimate of the Dusky Seaside Sparrow. Wilson Bulletin 82:158–166. Close ).

Density

Highest breeding densities reported from Long Island, New York (Oak Beach) and Delmarva Peninsula (Little Creek, Delaware and Elliott's Island, Maryland) (113 Greenlaw, J. S. (1992). Seaside Sparrow, Ammodramus maritimus. In Migratory Nongame Birds of Management Concern in the Northeast (K. J. Schneider and D. M. Pence, Editors). U.S. Department of the Interior, Fish and Wildlife Service, Newton Corner, MA, USA. pp. 211–232. Close ). Singing male densities in ditched marshes, 0.6–1.0 males/ha (2 Woolfenden, G. E. (1956). Comparative breeding behavior of Ammospiza caudacuta and A. maritima. University of Kansas Publications of the Museum of Natural History 10(2):45–75. Close , 3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close , 176 DeRagon, W. R. (1988). Breeding ecology of Seaside and Sharp-tailed sparrows in Rhode Island salt marshes. M.S. thesis, University of Rhode Island, Kingston, RI, USA. Close ); densities in unaltered marshes, 0.3–20.0 males/ha (231 Springer, P. J., and R. E. Stewart (1948). Breeding-bird census no. 12: tidal marshes. Audubon Field Notes 2:223–226. Close , 232 Quay, T. L. (1953). Habitat and territory in Macgillivray's Seaside Sparrow. Journal of the Elisha Mitchell Scientific Society 69:99. Close , 174 Norris, R. A. (1968). Seaside Sparrow: western Gulf Coast subspecies. In Life Histories of North American Cardinals, Grosbeaks, Buntings, Towhees, Finches, Sparrows, and Allies (O. L. Austin Jr., Editor) U.S. National Museum Bulletin No. 237, part 2. pp. 841–849. Close , 161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close , 118 Post, W. (1970). Breeding bird census no. 46: salt marsh. Audubon Field Notes 24:771–772. Close , 130 Post, W. (1981). Breeding bird census no. 200: salt marsh. American Birds 35:99. Close ).

No estimates of winter population densities, although Beaton's (192 Beaton, G. (1993). Effects of unusually high tides on some coastal species or does anyone have an ark? Oriole 58(1–4):22–23. Close ) observation of 228 birds gathering on an 8 m² island suggests a large number winter within a circumscribed area.

Trends

Survey-wide results from the BBS indicated a mean increase of 1.0% (95% CI: –1.1, 3.7; n = 28 survey routes) per year from 1966 to 2019 (233 Sauer, J. R., W. A. Link, and J. E. Hines (2020). The North American Breeding Bird Survey, Analysis Results 1966–2019. U.S. Geological Survey data release. Close ). Regional BBS trends during the same time period indicated potential declines; e.g., the New England/Mid-Atlantic Coast Bird Conservation Region (BCR 30) had a mean decrease of 0.9% (95% CI: –2.4, 0.4; n = 13 routes) per year (233 Sauer, J. R., W. A. Link, and J. E. Hines (2020). The North American Breeding Bird Survey, Analysis Results 1966–2019. U.S. Geological Survey data release. Close ). However, both survey-wide and regional results must be treated with caution given the limited sample size for BBS routes and the species' generally low abundance on surveys. Using a large point-count data set collected from Maine to Virginia, Correll et al. (234 Correll, M. D., W. A. Wiest, T. P. Hodgman, W. G. Shriver, C. S. Elphick, B. J. McGill, K. M. O'Brien, and B. J. Olsen (2017). Predictors of specialist avifaunal decline in coastal marshes. Conservation Biology 31(1):172–182. Close ) reported no population trend for Seaside Sparrow between 1994 and 2012.

A. m. macgillivraii populations were recently reported to be declining in the southeastern United States (67 U.S. Fish and Wildlife Service (2018). Species status assessment report for the MacGillivray's Seaside Sparrow (Ammodramus maritimus macgillivraii). Version 1.3. U.S. Fish and Wildlife Service, Region 4, Athens, GA, USA. Close ).

A. m. mirabilis populations declined 58% between 1992 and 1995 (139 Curnutt, J. L., A. L. Mayer, T. M. Brooks, L. Manne, O. L. Bass, D. M. Fleming, M. P. Nott, and S. L. Pimm (1998). Population dynamics of the endangered Cape Sable Seaside Sparrow. Animal Conservation 1(1):11–21. Close ). Historical site occupancy trends (surrogate of abundance) showed that this subspecies has experienced two episodes of decline, but recently while two subpopulations continue to decline in occupancy, one exhibits consistent increases (235 Cassey, P., J. L. Lockwood, and K. H. Fenn (2007). Using long-term occupancy information to inform the mangement of Cape Sable Seaside Sparrows in the Everglades. Biological Conservation 139:139–149. Close ).

A. m. nigrescens was estimated at 900 males in 1968, with presumably equal number of females (230 Sharp, B. (1970). A population estimate of the Dusky Seaside Sparrow. Wilson Bulletin 82:158–166. Close ), though the subspecies was extirpated by 1980 (236 Delany, M. F., W. P. Leenhouts, B. Sauselein, and H. W. Kale II (1981). The 1980 Dusky Seaside Sparrow survey. Florida Field Naturalist 9:64–67. Close ).

The Seaside Sparrow occupies an intermediate position along moisture gradients (230 Sharp, B. (1970). A population estimate of the Dusky Seaside Sparrow. Wilson Bulletin 82:158–166. Close , 115 Greenlaw, J. S. (1983). Microgeographic distribution of breeding Seaside Sparrows on New York salt marshes. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 99–114. Close ) and are therefore sensitive to hydrologic changes and the associated vegetation responses. Small changes in marsh relief may have large effects on vegetative structure and thus on sparrow abundance (113 Greenlaw, J. S. (1992). Seaside Sparrow, Ammodramus maritimus. In Migratory Nongame Birds of Management Concern in the Northeast (K. J. Schneider and D. M. Pence, Editors). U.S. Department of the Interior, Fish and Wildlife Service, Newton Corner, MA, USA. pp. 211–232. Close ). Changes to vegetation structure driven by increased sea levels and the associated altered hydrology are predicted to have substantial impacts on populations (237 Shriver, W. G., and J. P. Gibbs (2004). Projected effects of sea-level rise on the population viability of Seaside Sparrows (Ammodramus maritimus). In Species Conservation and Management: Case Studies (H. R. Akcakaya, M. A. Burgman, O. Kindvall, C. C. Wood, P. Sjorgren-Gulve, J. S. Hatfield, and M. A. McCarthy, Editors). Oxford University Press, Oxford, United Kingdom. pp. 397–409. Close , 218 Kern, R. A., and W. G. Shriver (2014). Sea level rise and prescribed fire management: Implications for seaside sparrow population viability. Biological Conservation 173:24–31. Close ). Reducing marsh loss and limiting conversion of vegetation dominated marsh to mud flat or open water would have a positive impact on population persistence (218 Kern, R. A., and W. G. Shriver (2014). Sea level rise and prescribed fire management: Implications for seaside sparrow population viability. Biological Conservation 173:24–31. Close ). In Georgia, the species currently use higher elevation areas within the marshes where they occur, a habitat that is predicted to decline by > 80% by the year 2100 (238 Hunter, E. A., N. P. Nibbelink, and R. J. Cooper (2017). Divergent forecasts for two salt marsh specialists in response to sea level rise. Animal Conservation 20:20–28. Close ).

Natural successional changes that convert low (intertidal) into high (supra-tidal) marsh (239 Niering, W. A., and R. S. Warren (1980). Vegetation patterns and processes in New England salt marshes. BioScience 30:301–307. Close ) represent potential problems over period of several hundred years (240 Redfield, A. C. (1972). The development of a New England salt marsh. Ecological Monographs 42:201–237. Close ). Long-term changes in sparrow productivity resulting from succession can be expected even in protected tidal wetlands; e.g., climate change may favor invasion of salt marshes by mangroves (49 Kale, H. W., II (1983). Distribution, habitat, and status of breeding Seaside Sparrows in Florida. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 41–48. Close ) in the long term but shorter term time scales.

In low-marsh habitats, areas dominated by Spartina alterniflora and other plant species adapted to daily tidal inundations, some sparrow populations are able to grow or stabilize replacement rates in face of losses from flooding or predation (3 Post, W., J. S. Greenlaw, T. L. Merriam, and L. A. Wood (1983). Comparative ecology of northern and southern populations of the Seaside Sparrow. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 123–136. Close ). Adults renest quickly after nest loss and recolonize other sites on the same marsh (116 Post, W. (1974). Functional analysis of space-related behavior in the Seaside Sparrow. Ecology 55:564–575. Close , 115 Greenlaw, J. S. (1983). Microgeographic distribution of breeding Seaside Sparrows on New York salt marshes. In The Seaside Sparrow, Its Biology and Management (T. L. Quay, J. B. Funderburg Jr., D. S. Lee, E. F. Potter, and C. S. Robbins, Editors). Occasional Papers of the North Carolina Biological Survey 5, North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 99–114. Close , 117 Marshall, R. M., and S. E. Reinert (1990). Breeding ecology of Seaside Sparrows in a Massachusetts salt marsh. Wilson Bulletin 102(3):501–513. Close ). Historic structural alterations to salt marshes like mosquito control ditches dug in the 1920’s and 1930s are extensive throughout marshes along the Atlantic coast (241 Bourn, W. S., and M. C. Cottam (1950). Some biological effects of ditching tidewater marshes. U.S. Department of Interior, Washington D.C. Research Report 19:1–42 Close ). The immediate effects of these alterations on sparrow population dynamics are not well documented, but there are clear shifts in vegetation community structure and composition with an increase in shrub cover and a reduction in open water (241 Bourn, W. S., and M. C. Cottam (1950). Some biological effects of ditching tidewater marshes. U.S. Department of Interior, Washington D.C. Research Report 19:1–42 Close ). Invertebrate diversity and abundance did not differ between marshes ditched for mosquito control in the 1930s or unditched marsh (242 Clarke, J. A., B. A. Harrington, T. Hruby, and F. E. Wasserman (1984). The effect of ditching for mosquito control on salt marsh use by birds in Rowley, Massachusetts. Journal of Field Ornithology 55:160–180. Close ) therefore one could surmise there would be no effect on sparrow food availability. There is a growing body of evidence indicating that historical ditching, installed nearly 100 years ago, does not negatively impact sparrow breeding success (116 Post, W. (1974). Functional analysis of space-related behavior in the Seaside Sparrow. Ecology 55:564–575. Close , 117 Marshall, R. M., and S. E. Reinert (1990). Breeding ecology of Seaside Sparrows in a Massachusetts salt marsh. Wilson Bulletin 102(3):501–513. Close , 4 Pepper, M. A., and W. G. Shriver (2010). Effects of Open Marsh Water Management on the reproductive success and nesting ecology of Seaside Sparrows in tidal marshes. Waterbirds 33:381–388. Close , 5 Roberts, S. G., R. A. Longenecker, M. A. Etterson, K. J. Ruskin, C. S. Elphick, B. J. Olsen, and W. G. Shriver (2017). Factors that influence vital rates of Seaside and Saltmarsh sparrows in coastal New Jersey, USA. Journal of Field Ornithology 88(2):115–131. Close ). Fluctuations in numbers reported from some areas. Between 1974 and 1975, male population at Taylor Slough, Florida, increased 75% (161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close ). Most populations in unaltered salt marshes relatively stable; e.g., at Gulf Hammock, Florida, over 6 years, density varied between 1.6 and 2.6 males/ha (WP; M. V. McDonald, personal communication). Coastal New Jersey populations were stable to 2050 based on a population viability model simulating the effects of sea-level rise on population persistence (6 Roberts, S. G., R. A. Longenecker, M. A. Etterson, C. S. Elphick, B. J. Olsen, and W. G. Shriver (2019). Preventing local extinctions of tidal marsh endemic Seaside Sparrows and Saltmarsh Sparrows in eastern North America. Condor: Ornithological Applications 121. Close ).

Because of the species' narrow coastal distribution, populations in any given area may be displaced by storms, fires, oil spills. Current gaps in distribution may be explained in part by history of such disasters (243 Tomkins, I. R. (1934). Hurricanes and subspecific variation. Wilson Bulletin 46:239–240. Close ). In northern part of range, sizes of overwintering populations determined by severity of weather (244 Bull, J. (1974). Birds of New York State. Doubleday Natural History Press, Garden City, NY, USA. Close ).

Disappearance of birds from local areas after large-scale catastrophes probably due to habitat alteration rather than direct mortality of adults (140 Pimm, S. L., C. N. Jenkins, and S. Bass (2007). Cape Sable Sparrow annual report 2007. Everglades National Park, Homestead, FL, USA. Close ). Small-scale fires cause temporary displacement of residents, which quickly move back (183 Baker, J. L. (1973). Preliminary studies of the Dusky Seaside Sparrow on the St. Johns National Wildlife Refuge. Proceedings Southeastern Association Game and Fish Commissioners 27:207–214. Close ); uncontrolled fires probably destroy even birds capable of flight (183 Baker, J. L. (1973). Preliminary studies of the Dusky Seaside Sparrow on the St. Johns National Wildlife Refuge. Proceedings Southeastern Association Game and Fish Commissioners 27:207–214. Close , 161 Werner, H. W. (1975). The biology of the Cape Sable Sparrow. Project completion report prepared for U.S. National Park Service, Everglades National Park, FL, USA. Close , 138 Sykes, P. W., Jr. (1980). Decline and disappearance of the Dusky Seaside Sparrow from Merritt Island, Florida. American Birds 34:728–737. Close ).

In the eastern Florida Everglades, A. m. mirabilis is severely threatened because of drainage, invasion of exotic trees, frequent human-caused fires, and agricultural and urban development (126 Kushlan, J. A., and O. L. Bass (1983). Habitat use and the distribution of the Cape Sable sparrow. In The Seaside Sparrow, Its Biology and Management. Occasional Papers of the North Carolina Biological Survey 5. North Carolina Museum of Natural Sciences, Raleigh, NC, USA. pp. 139–146. Close ). Reduction of western Everglades population in Big Cypress, Florida, attributed to water-level manipulations (140 Pimm, S. L., C. N. Jenkins, and S. Bass (2007). Cape Sable Sparrow annual report 2007. Everglades National Park, Homestead, FL, USA. Close ).