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PPSR0 0 8) 06/2 T 492:8 56 U.S. Fish & Wildlife Service Status Assessment and Conservation Plan for the Black Tern in North America W. David Shuford Point Reyes Bird Observatory 4990 Shoreline Highway Stinson Beach, CA 94970 April 1999 Status Assessment and Conservation Plan for the Black Tern (Chlidonias niger surinamensis) in North America . W. David Shuford Point Reyes Bird Observatory 4990 Shoreline Highway Stinson Beach, CA 94970 For additional copies or additional information, contact: Nongame Bird Coordinator U.S. Fish and Wildlife Service Denver Federal Center Denver, CO 80225-0486 April 1999 -\ Recommended citation: Shuford, W. D. 1999. Status assessment and conservation plan for the black tern (Chlidonias niger surinamensis) in North America. U.S. Department of Interior, Fish and Wildlife Service, Denver, CO. U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 TABLE OF Eo iii ete oi eee ne een teen dhe dial Vill CONTENTS ES, ninth di eail hdiek e bi heehee deeneeene beeel l i ai itll itt talline deli ee ee ad 2 nis a indi iti nena ended ehhh beeen cide 2 DD ‘ne00s Cinieehh bees dhe iheeh seceeeend 2 ae ace tal dean ele hes ede a he ae ee ome 2 EE en er 2 Central and South Americas ......ccc. ce.ce. ec .ec.e e.en s 2 inti petebeneensnens ouaennsenesentssenss—ensess 4 Geosrapnic DistiDution ... wc crcccec ccc sceveveeseeveveevers 4 6+) 660 6c0¢ne dnbecumeteehineabaackansenoneesbé 4 TD .606020005n00000000000000000000000060000000005 4 DEE 66nns pee ccecackeceneecisedibehseensieatsseserees 6 EE «+ 60 0066ecenngenbeeeeseeereeseenenes 6 Ph ht hn nenhons0$eseebSe0 bb0nhnesnsess0so01eesseeeens s 6 ED 2.05205000000000450006900000800000000000000000 6 Dh +4 enncn pckenesdeas1asbnneeeeseouneseseeseseces 6 ee 6 Reproductive phenology ......00. ce.eee.e e.ee .eee. ee ns 8 Breeding site fidelity .. 0... ccc cece cece ecevecececs 8 Demography and limiting factors ..........c.ec.e. .ee e 8 ED $34960460600600060056000060005000000000008 9 SE b5046066:56640-046-00490400000000000000000000008 9 Population Estimates and Trends ......0.0.0 .ce.e ee.e .ee .en s 9 SED 4.4-60-0-0040.06060060000000046000000000000000000008 9 TED bo54450060040460:0006000000004000000000000000088 1] WUOTNUNUTUNS PACUIVINIES wccece eer ee ee eeeeeeeeseees 15 BPOOGING BG BUTVEYE ceceeee ee ee eeeeens 15 State and Provincial Surveys ......00.. c.ece. e.ee .ee .een s 16 FEGDIGRE FROGUITOIIGINS cccecce ec ee ee eeeseecees 16 ED 6 0s 4.00:0040000000000000000000000000000008 16 SEED 0460040040 +0 0000000200000000000600001000080008 17 Winter and Summer Nonbreeding Seasons ................... 20 WD 65:50:00.4 040000 0000060090000000000000000000000000008 20 SE 6:590.0406099.0)0000000000400000-000000000000050088 20 ED ee 5000 00040000000080000200000008000988 22 A PPP TETTETITITTSTTTETETLTTTTTeeeeee 22 Inadequacy of Existing Regulatory Mechanisms .............. 22 Other Natural or Manmade Factors ..................0.000005 23 Pesticides or other contaminants ..................0000- 23 Population size and isolation ................e.ee0 eee e 24 ED 66.66044s00040000400000000000000008 24 eh 6446000069000060000400000000000000000000000005 24 Habitat and Vegetation Management ....................04. 24 PO POURS gcccc cceccccecec veseens 27 IE 00 60.6-400024000000006000000000000084 27 U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 TT Recommendations on Current Status.......0.....000eeee e dial 28 LT ee 28 i ite ete eee ce eneeneeensegnnabenia 28 Habitat Management and Protection ......0..... 0.e s.ev.en s 29 DT © titnneien ed o00404000000000060008006048 29 tind aint eee helnntt eben pil 30 eeee a ENN 30 ki RE a a Ee Ny RE 31 Se rn ane a 32 Appendix 1. Summaries for States, Provinces, and Territories within the breeding range in the United States Th bis ncn ep pee ees eines Oethene keen nes 64 United States ON a it a ee lain el he ee lel 65 ESe y ee eee 65 nth sep peehieeenece sbne ebeibdi e 69 Dh pp tthhhebe sees enbesiaaebdined s 70 DE os¢ shen cedebe 400d00i boacseeeehs 71 tn tttptppobieoss50000006000000000hi 72 Pn 66566064406000000000006604006004006 73 Di ££54644046060000000000008040600a0 75 ED 0.660020000000000400000060006084 76 ED 6460666 000000441000000000600040064 77 ED 0.0.6000004000400006090000000000% 78 I + ++ 04060600600046006000000000% 80 TD o0.654000200000000000000000000004 83 PD 204004 90090004090000000000000008 83 Ss 46 4.000:000000000400000000800000 84 ED 000 00:00000020000620000600000000080 86 SPEED 5.600000 60000000000000000000004 87 ey UD 6.06 6-000000000000900000000006604 88 DD «6606960 60000000090000000002 93 SD 9000-0000000000000000000600000000006 94 PED 64055000 0400000 000000008000400008 95 PEED ve ceaeeecevveveneeeeesenenan 97 I o654565200090000000000800008 99 Se 640646040000024071990000020400000008 100 EE 5660609040 000000000000000000000 101 ED 46 o0600000000000000000000088 103 Ss 6 0.0600000060000000460600000002 104 SEED 9 0 000 0000060000000000000000004 107 Canada Dn 62560 600400000600000000000000064 108 British Columbia ...............c0ee0 0ue e 108 U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 a alain ial iliac 110 New Brunswick and Nova Scotia ........... 111 Northwest Territories ............ 00000 eee 112 ae e a 113 ee i eee ee kn 116 ie tin eal tt e 117 ali hide aet ink et adie len ia te a eae 118 Appendix 2. Regional, State, Provincial, and Territorial contacts and contributors. ..............e0ee eeee s 120 U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 v LIST OF TABLES Table 1. Government and Natural Heritage conservation AND FIGURES breeding status rankings for the Black Tern for 34 states, provinces, and territories in North America. .... Table 2. Apparent historical population trends of the Black Tern in 34 states, provinces, and territories in North America. Data from Appendix 1. ....... 0. cc cece eee eee eens . 12 Table 3. Breeding Bird Survey (BBS) population trend estimates for Black Terns during the 1966-1996, 1966-1979, and 1980-1996 intervals for all states, provinces, strata, and regions where they have occurred on >14 routes over the entire survey period (Sauer et al. 1997). BBS regions are defined in Bystrak (1981). Trend is presented as average % SE, n.00.0:0000400608008> sennntendees vee Figure 1. Current breeding, summer nonbreeding and wintering distribution of the Black Tern in North America, Central America, and northern South America. See Appendix | for details of breeding distribution. Nonbreeding summer distribution along the Gulf and Atlantic coasts of Ce‘ral America is not well known. ..............0ce0e 0eece s 8 Figure 2. Winter (Oct-Mar) distribution of Black Terns in the eastern Pacific from several years of at-sea surveys in the last 20+ years (Courtesy of R. L. Pittman). .......... re Figure 3. Relative abundance of Black Terns from Breeding Bird Survey routes in the United States and southern Canada, 1966-1996 (Sauer et al. 1997). 20... eee eee eee . 10 Figure 4. Annual population trend of Black Terns from Breeding Bird Survey routes in the United States and southern Canada, 1966-1996; change in percent per route per year SEED UE 69500 060006660060 06000000400900 8 . 14 vi U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 CONVENTIONS USED In Table | and in each state, provincial, or territorial account (Appendix IN THE TEXT 1), The Nature Conservancy's standardized subnational (state/provincial) SRANK priority categories (codes) for breeding (B) are expressed as their verbal equivalents (TNC 1996). The SRANK codes, verbal equivalents, Natural Heritage Ranks and definitions are: SX = Extirpated (element believed to be extirpated from the state, province, or other subnational unit). S1 = Critically Imperiled (critically imperiled in the state because of extreme rarity or because of some factors making it especially vulnerable to extirpation from the state; typically 5 or fewer occurrences or very few remaining individuals or acres). S2 = Imperiled (imperiled in the state because of rarity or because of some factors making it very vulnerable to extirpation from the state; typically 6 to 20 occurrences or few remaining individuals or acres). S3 = Vulnerable (vulnerable in the state either because rare and uncommon, or found only in a restricted range, even if abundant at some locations, or because of other factors making it vulnerable to extirpation; typically 21 to 100 occurrences). S4 = Apparently Secure (uncommon, but not rare, and usually widespread in the state; usually more than 100 occurrences). SS = Secure (demonstrably widespread, abundant, and secure in the state and essentially ineradicable under present conditions). S? = Unranked (state rank not yet assessed). SA = Accidental (accidental or casual in the state, i.e., infrequent and outside usual range; includes species recorded once or only a few times, a few of which may have bred on the one or two occasions they were recorded). Occasionally rankings combine two of these categories (e.g., S3S4 = Vulnerable/Apparently Secure). For purposes of this report, the Black Tern is considered of "conservation concern" in the states and provinces that list the species as Critically Imperiled, Imperiled, or Vulnerable. Acronyms Used BBS = Breeding Bird Survey GIS = Geographic Information System NASFN = National Audubon Society Field Notes NWR = National Wildlife Refuge SWA = State Wildlife Area USFWS = US. Fish and Wildlife Service WA = Wildlife Area WMA = Wildlife (or Waterfowl) Management Area WPA = Waterfowl Production Area Descriptive Statistics Depending on completeness of the data source, the central tendency of data is usually expressed as an average [minimum-maximum, Standard Error (SE), sample size (n)]. U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 vii ACKNOWLEDGMENTS I am extremely grateful to the over 100 people who ‘ook time from their busy work schedules aiid private lives to provide me with reports, unpublished data, and insight about the status and biology of Black Terns, without which this report would not have been possible. These contributions were supported by a host of state, federal, and private organizations. Most of these individuals and institutions are cited in the text or are listed in Appendix 2. Albert Beintema, Hans Blokpoel, John Cooper, Jeanne Hickey, George Linz, Irene Mazzocchi, Ian Nisbet, Bruce Peterjohn, and Chip Weseloh were very helpful in providing the in-press versions of their articles from the Black Tern symposium prior to their publication in Colonial Waterbirds, which allowed incorporation of the latest findings on Black Terns in the report manuscript before it was sent out for review. Thanks to the following individuals for reviewing the entire report or individual state, provincial, or territorial summaries: Rob Alvo, Diane Amirault, Pierre Aquin, Doug Backlund, Hans Blokpoel, Dan Brauning, Bill Busby, John Castrale, Andrea Cerovski, John Cooper, Ellie Cox, Christine Custer, John Dinan, James Dinsmore, Kristi DuBois, Erica Dunn, Tony Erskine, Mike Fournier, Jim Herkert, Jerry Horak, Stephanie Jones, Tom Kent, Hugh Kingery, Charles Kjos, Rudolph Koes, Steve Lewis, Mark McCollough, Richard Malecki, Sumner Matteson, Steve Maxson, Irene Mazzocchi, Bob Miller, Wayne Mollhoff, Dave Naugle, Larry Neel, Eric Nelson, Ian Nisbet, Steve Parren, Diane Pence, Bruce Peterjohn, Fritz Prellwitz, Michael Richardson, William Scharf, Nat Shambaugh, Ella Sorensen, Mark Stern, Eileen Dowd Stuckel, Chuck Trost, Bill Tweit, Chip Weseloh, and Tara Zimmerman. The Nature Conservancy and the International Network of Natural Heritage Programs and Conservation Data Centers provided much valuable unpublished data. Joanne Munro prepared the map in Figure 1, Rusty Scalf helped in the preparation of the map, and Garreth Penn and Maggie Brown provided important references. Funding to attend the Black Tern symposium at the Colonial Waterbird Society meeting in Charleston and to prepare this report was provided by the U.S. Fish and Wildlife Service Regional Nongame Migratory Bird Coordinators Tara Zimmerman (Region 1), Steve Lewis (Region 3), Chuck Hunter (Region 5), and Stephanie Jones (Region 6). Many thanks to Stephanie Jones for sheparding the manuscript through the review and publication process and to Melvie Uhland and Laura Hubers for design and publication. This is Contribution No. 728 of Point Reyes Bird Observatory. Vill U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 SUMMARY The Black Tern (Chlidonias niger surinamensis) has been a species of concern in North America because of continentwide population declines, particularly since the 1960s. Currently the species is listed as Threatened or Endangered in 6 states and is considered of conservation concern in 18 other states and provinces. Breeding Bird Survey data indicate that Black Terns declined significantly survey-wide at an average rate of 3.1% annually (61.1% overall) from 1966 to 1996. Also during this period, the Canadian population decreased significantly at an average annual rate of - 3.5% (-65.7% overall), whereas the U.S. population showed no significant trend. These declines largely reflect trends prior to 1980, and most trends were reversed in the 1990s. The North American population recently has leveled off or increased slightly. The species still occupies most of its former range, and the continentwide breeding population probably still numbers in the low to mid hundreds of thousands. The main causes of population declines in North America appear to be habitat loss and degradation on the breeding grounds, although introduced species, human disturbance, and contaminants may be contributing factors. Since the 1950s, the freshwater emergent wetlands upon which the species depends for breeding have declined by 25%. Very little is known, however, about threats to the Black Tern during migration and winter, which account for 8 to 9 months of the species' annual cycle. Recovery of Black Tern populations likely will require a combination of management efforts and policy initiatives to improve habitat conditions and nesting success. Conservation priorities are (1) refining monitoring techniques to better detect population trends and determine the causes of changes, (2) stemming the tide of wetland loss by forming partnerships to protect and restore wetlands from a landscape perspective, (3) managing habitat for Black Terns based on current knowledge while conducting further research to identify limiting factors and evaluate additional management techniques, and (4) educating the public about the value of wetlands and possible effects of their actions on Black Terns. U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan for the Black Tern - April 1999 I