A Summary of Christmas Bird Counts in Latin America, the Caribbean, and Bermuda Continued from Page 23

A Summaryof Christmas Bird Counts in Latin America, the Caribbean, and Bermuda

Daniel K. Niven1 and Gregory S. Butcher2 1 National Audubon Society, Illinois Natural History Survey, 1816 South Oak Street, Champaign, IL 61820; [email protected] 2 National Audubon Society, 1150 Connecticut Avenue, NW, Suite 600, Washington, DC 20036; [email protected]

Introduction Since the first group of New York City “birders” set out to count birds on Christmas Day in 1900, as an alternative to the annual bird hunt that was common at the time, Christmas Bird Counts have continued to grow in popularity (Butcher 1990). People participate for many reasons, including the social and educational aspects of gathering to count birds, the competitive sport of it, and, more recently, because the conservation value of the data collected on these counts has been further recognized (Sauer et al. 2004). The majority of counts have been conducted in the continental United States and southern Canada. As each year passes, the value of this extensive long-term database, currently with counts from approximately 2000 locations A Blue-gray Tanager (Thraupis episcopus) and Christmas Bird Counters in Colombia—two things and data on more than 500 species, continues to increase. likely to be encountered during the CBC season in CBC data have been used in hundreds of scientific publi- South America. Photos/Jorge Botero cations (LeBaron 2010), and recent analyses of these data have proved useful for assessing the abundance, distribution, and trends of North American wintering birds (Link et al. 2006) and for assessing distributional impacts of climate change (Niven et al. 2009).

Daniel K. Niven is Audubon’s Senior Scientist for Bird Conservation, a past Director of Audubon’s Important Bird Areas Program, and Audubon’s principal CBC analyst. Niven, who received his Ph.D. from the University of Illinois, brings to Audubon a lifelong interest in birds and conservation, having participated in CBCs since he was a child.

Gregory S. Butcher is Director of Bird Conservation for the National Audubon Society. He has a Ph.D. in Zoology from the University of Washington. Butcher previously served as Director of Bird Population Studies at Cornell University’s Laboratory and is a Fellow of the American Ornithologists’ Union.

18 AMERICAN BIRDS Regularly conducting CBCs in other Table 1. The number of CBC circles for which at least one CBC was conducted, and the locations throughout the Western total number conducted during the 38-year period between December/January of 1972–73 Hemisphere would be of great value, and 2009–10. particularly because so many species # run # run # run Region/Country # CBCs # CBC 10-plus 20-plus 30-plus present in the U.S. and Canada during conducted circles years years years the breeding season are migratory and Caribbean and Bermuda 362 33 14 6 2 because there is great interest in the pop- Bahamas 69 9 4 ulation status of all birds. And although Bermuda 35 1 1 1 1 we have learned a lot about the distribution, ecology, and behavior of migrants Cuba 4 1 during the nonbreeding season (Keast Dominican Republic 42 3 2 1 and Morton 1980, Rappole et al. 1983, Grenada 2 1 Hagan and Johnston 1992, Martin and Jamaica 1 1 Finch 1995), there is still much we do Puerto Rico 90 7 2 1 1 not know (Faaborg et al. 2010a,b), and Turks and Caicos Islands 1 1 even less is known about the population Virgin Islands (British) 32 3 1 1 status of most species in the Western Hemisphere that breed outside the U.S. Virgin Islands (U.S.) 86 6 4 2 and Canada. Regularly conducting CBCs in locations south of the U.S., Mexico 414 49 15 6 0 however, has historically been difficult for a number of reasons. The majority of Central America 354 42 10 7 4 these countries lie in tropical regions Belize 92 5 3 3 1 where the diversity of birds is high, the Costa Rica 94 16 3 1 relative abundance of each species is often low, and many of the species are El Salvador 6 1 relatively quiet, cryptic, and live in dense Guatemala 19 10 vegetation, making their detection and Honduras 8 1 identification more difficult than in the Nicaragua 5 2 northern latitudes. Yet in spite of the Panama 130 7 4 3 3 often daunting challenges of conducting CBCs in the tropical and austral regions South America 306 89 6 2 1 of the Western Hemisphere, interest has grown rapidly, and the number of skilled Argentina 4 4 and motivated birders continues to Brazil 47 11 2 increase. Here we report the first sum- Chile 16 4 mary of Christmas Bird Counts Colombia 124 45 1 1 conducted south of the United States. Ecuador 40 6 1 Guyana 1 1 The Location and Number of CBCs Paraguay 3 1 Christmas Bird Counts were first Peru 16 4 reported from Latin America and the Caribbean in 1973 (National Audubon Trinidad and Tobago 35 2 1 1 1 Society 1973). That year seven counts Uruguay 8 8 were reported. Two of these were from Venezuela 12 3 1 Mexico (El Naranjo, San Luis Potosi and Gomez Farias, Tamaulipas) and one each Total 1436 213 45 21 7 from Belize (Belize City), Guatemala (Lake Amatitlan), El Salvador (San been run at 213 locations in Latin year period since 1972–73, 1436 CBCs Salvador), Puerto Rico (Cabo Rojo), and America, the Caribbean, and Bermuda; were conducted in Latin America and the the U.S. Virgin Islands (St. Croix). By moreover, the locations of the CBCs Caribbean (Table 1); Mexico has led the 1976, counts had been run at 59 locations, have been quite widespread (Table 1). way with 414 counts, followed by 362 including the first from South America Another way to summarize CBC effort reports from the Caribbean and (Rancho Grande, Aragua, Venezuela). is to look at the total number of CBCs Bermuda, 354 from Central America, Since these humble beginnings CBCs have conducted in each country. Over the 38- and 306 from South America.

THE 110TH CHRISTMAS BIRD COUNT AMERICAN BIRDS 19 The amount of effort invested in Latin American and Caribbean CBCs is impressive, especially considering the slow but steady increase in the number of counts conducted in the region. One count in particular has the distinction of having been run every year since 1973 (Cabo Rojo, Puerto Rico), and the three counts in the Atlantic, Central, and Pacific canal areas of Panama have been run every year since 1974. But overall Figure 1. The number of Christmas Bird only seven counts have been run for at Counts conducted each year in Latin least 30 years, including the four already America, the Caribbean, and Bermuda mentioned, as well as the Belize City, Figure 2. The number of Christmas Bird between December/January 1972–73 and Trinidad, and Bermuda counts. An Counts conducted regionally between 2009–10. additional 14 counts have been run at December/January 1972–73 and 2009–10. These counts involved the effort of least 20 times (Table 1). Therefore, only 26,882 “person days” (the actual number 21 circles have been counted for at least endless array of questions to address of observers is much smaller because 20 years in Latin America and the with these data. As the database grows many dedicated observers have partici- Caribbean. Only 45 of the 213 CBC and the data become more accessible, we pated for many years and often on more circles have been counted at least 10 expect to see many worthwhile research than one count per year), logging more times (Table 1). Considering the projects make use of them. But a full than 91,726 miles by car, as well as many immense size of the region, we do not analysis of the database is beyond the more miles on foot and by canoe, bike, or yet have sufficient data for many mean- scope of this preliminary report. For other means. In CBC analyses, effort is ingful statistical analyses, such as trend example, due to the complexity of the often summarized in terms of the num- detection, but prospects for the future taxonomic changes that have occurred ber of “party hours.” Normally each are very promising. The number of since 1973, and the multiple common 15-mile diameter CBC circle is divided counts reported annually has continued names and species codes that have been into a variable number of areas, and to increase, from 7 during the 1972–73 used, it is not even a trivial task to deter- observers organize into small groups count to 99 for the 2009–10 count mine the number of species that have called field parties, each of which covers a (Figure 1), and these increases have also been detected. different sector. The number of party been widespread regionally (Figure 2). Our focus here is on species with pop- hours is the sum of the number of hours ulations that occur in the U.S. and each party spends looking for birds. In Bird Summaries: Overall Patterns Canada, with a particular focus on conducting these 1436 CBCs, a total of On the 1436 CBCs that have been migrants. Specifically, we have restricted 71,757 party hours were invested looking conducted in Latin America and the our analysis to species that regularly for birds. That is equivalent to one person Caribbean since 1973, a total of approx- occur in the U.S. and/or southern working every day around the clock for imately 8,900,000 birds has been Canada (i.e., species for which the U.S. more than eight years. reported. Considering the size of the must take some conservation responsi- current database in terms of the number bility) and that have been included in of counts and individuals birds detected, the recent U.S. State of the Birds reports as well as the temporal and geographic scope of coverage, there is an almost

20 AMERICAN BIRDS (NABCI 2009 and 2010). Moreover, recognizable populations that do not occur in the U.S. or Canada were A Tropical Adventure excluded, even if other populations of the species are included (for example, G. Thomas Bancroft on the 110th CBC Southern House Wren populations were not included if they were reported as I had the honor of being invited to Costa Rica last December to participate on the Rainforest Aerial such). In other cases, widespread species Tram Christmas Bird Count and help them commemorate the work of Alexander Skutch. We were also may not have recognizable sub-popula- celebrating the 15th anniversary of the Aerial Tram, whose count boasts many exceptional species and tions south of the U.S. (for example, records. many waterbirds); therefore, southern The adventure began on an exciting note when Maryland received 20-plus inches of snow the populations of these species have been morning I was to leave. All flights were canceled, and my initial airline couldn’t fly me there until well included in our analysis. Given these after the Skutch celebration. Three days and another missed connection later I arrived in Costa Rica at complexities of distribution and taxono- 10 P.M. and was met by CBCer Alan Rodriguez, who drove me one hour northeast to near Flores, my and regional differences in the Costa Rica. migratory behavior of some species, one I made it just in time to put down my bags and rest a few hours. We started the CBC at 5 A.M. the must use caution when interpreting next morning: 82 participants traveling mostly on foot, though some by car through the lush rainforest, these numbers. second-growth forest, and farmlands. I was part of a team that included Alan Rodriguez and Julio Sanchez. The very first call we heard in the lowland tropical wet forest was the chip note of a Wood Thrush, and these birds were common throughout the day. Chestnut-sided Warblers were the most ■ Species summaries for the entire region common bird we saw; it seemed like every time I turned around we would see another. About mid- The total number of species that morning, after having just seen a small group of Crested Guans, Julio spotted something on the far occur regularly in the U.S. and have side of the valley. Alan sent for a scope, and while we waited several Scarlet-rumped Caciques worked been recorded on a CBC in Latin the trees below. Through the scope, we were able to see a Tiny Hawk perched on a small snag. In the America, the Caribbean, or Bermuda at early afternoon, we found a male Bare-necked Umbrellabird. I had not imagined that we would even least one time since 1973 is 543 species. hear this spectacular bird, and having the chance to see it so well was just amazing. Of these, 175 species have been classi- At day’s end the CBC participants met in an open-sided restaurant to tally the count. While we fied as neotropical (long-distance) worked on the tally, a Crested Owl watched from a branch in the forest, searching for prey that might migrants and 227 as temperate migrants be attracted to the lights. It was a spectacular close to the count. (wintering mostly north of the Tropic of The following morning we took a quick ride on the aerial tram to see and listen for birds. Alan and Cancer) for the recent State of the Birds Jim Zook, the compiler for the count, rapidly identified a large number of species that were calling Reports (NABCI 2009 and 2010). An through the forest—tinamous, woodpeckers, parrots, and others. A short walk through the forest before additional 110 species that have popula- we left flushed a Gray-breasted Crake, a very secretive bird that darted away from us into the wet tions occurring in the U.S. have been undergrowth. classified as permanent residents, and 11 Later that morning Alan, gifted Costa Rican bird artist Cope, and I birded pasture and second- species are exotic or introduced species. growth habitat near Flores. This was still in the overall circle and an area where Cope had birded These four groups include 523 (96.3 during the count on the previous day. Because it was more open habitat and second-growth forest, percent) of the 543 U.S. species that we found many species that I had not seen earlier in the count. have been reported on one or more One of the most remarkable moments happened when Alan and Cope were working hard in one Latin American/Caribbean CBC. The second-growth patch of forest to show me a male White-collared Manakin. They must have seen it a additional 20 species reported from the dozen times, but I kept missing it. As we were searching, an Ovenbird popped up and sat for a few region include 13 mostly pelagic species seconds on a branch a few feet off the ground. This was a new and exciting bird for Alan; a few min- as well as a few vagrants and Pacific utes later I had a great look at a male manakin. In the course of searching we found several display migrants, and these are not included in sites where males had cleared a patch of forest floor for their communal mating displays. The open the rest of our summaries here. habitat gave us great birding, and we spotted six species of woodpeckers, 13 flycatchers, three tou- cans, as well as many others. Late in the day, we had started our long walk back to the car when Alan heard a faint call that made him stop to listen more intensely. A quarter-mile behind us in a forest patch we had just left, Alan thought he heard the call of a Purple-throated Fruitcrow. We debated whether to walk back to find this very secretive and hard-to-see large cotinga. We had already come this far, so we turned around and were rewarded with a good look at this spectacular bird. In two days, I had seen 143 species within the CBC circle. I was thrilled with my total, but this was far short of the 382 species seen by the 82 participants on this count. Alan dropped me back at the San José airport less than 46 hours after he picked me up; a fitting close to one of my most memo- rable Christmas Bird Count experiences. ■

THE 110TH CHRISTMAS BIRD COUNT AMERICAN BIRDS 21 Overall, the most widely detected species was Turkey Vulture, considered primarily a neotropical migrant in the U.S., but with widespread resident populations in the U.S. and farther south. It was detected at least once in 155 (72.8 percent) of the 213 CBC circles (Table 2). Great Egret, also considered primarily a neotropical migrant in the U.S. by NABCI (2010), but with widespread A Chestnut-sided Warbler (Dendroica pensylvanica), one of 382 found on the resident populations, was a close second, Rainforest Aerial Tram, Costa Rica, count this season. Photo/G. Thomas Bancroft with reports from 145 CBC circles. The most common species in the Latin 200,000 birds contributed in large part Table 2. U.S./Canadian breeders with American and Caribbean database clas- to the species being the highest-ranked reports from the most CBC circles in Latin sified in the U.S. as a temperate migrant species in terms of total birds reported America and the Caribbean (out of 213). was Cattle Egret, which was still a relative (summing individuals on all 1436 Species # CBC Circles newcomer to the Western Hemisphere counts) with 476,841 individuals (Table Turkey Vulture 155 when CBCs were initially reported from 5). When compared to the total of Great Egret 145 the region in 1973. They have been 310,945 birds for the next most abun- Cattle Egret 141 detected on 141 (66.2 percent) of the dant temperate migrant, the Cattle Spotted Sandpiper 137 213 counts. Black Vulture was the most Egret (Table 5), the influence of that sin- Black Vulture 137 commonly reported permanent resi- gle day at San Blas becomes apparent. Snowy Egret 136 dent, found in 137 circles, and Rock Among permanent residents, the Great- Tropical Kingbird (includes Couch’s Pigeon topped the list for exotic species tailed Grackle was most abundant with in Mexico, Belize, and Guatemala) 135 with reports from 103 circles, but this 198,955 birds reported, whereas Laughing House Wren 134 did not make the top 10 list for all Gull was the most abundantly reported American Kestrel 127 species. In terms of the total number of neotropical migrant (99,781 birds). reports, the species in each migratory House Sparrow was the most abundant Table 3. U.S./Canadian breeders occurring category that were most widespread were exotic species (82,156), but again, no on the most CBC reports (out of 1436). also the most consistently reported, with exotic species made the top 10 list. In Species # Reports the exception that Great Egret was each of these cases, the congregatory Great Egret 1115 reported on the highest percentage of the behavior of the species clearly was in large Cattle Egret 1106 counts: 1115 (77.6 percent of the 1,436 part responsible for this pattern of report- Spotted Sandpiper 1059 counts; Table 3). ed abundance. The highest single-day Turkey Vulture 1016 The vagaries of weather conditions, count for a neotropical migrant was Snowy Egret 979 opportunities for people to participate, 25,300 for Dickcissel on the 1976–77 American Kestrel 953 and many other factors contribute to count from Hato Masaguaral, Venezuela; Yellow Warbler 929 annual variations in counts at specific and for a permanent resident, it was Great Blue Heron 929 circles. Nonetheless, we can still learn a Great-tailed Grackle (7036 on the Little Blue Heron 920 lot by summarizing data from individual 1979–80 count from San Salvador, Black-and-white Warbler 903 counts. Whereas Cattle Egret, Black Vulture, and Rock Pigeon were the most Table 4. Highest counts of U.S./Canadian breeding species on a single day at a single place. widespread and frequently detected Year temperate migrant, permanent resident, Species # Birds (Dec.) CBC and exotic U.S. species, respectively, the Red-winged Blackbird 200,000 1980 San Blas, Nayarit, Mexico highest individual count of a species Brown-headed Cowbird 60,010 1983 San Blas, Nayarit, Mexico on a single day at a single site was for Cattle Egret 59,221 1992 La Selva, Lower Braulio Carillo N.P., Costa Rica Red-winged Blackbird: 200,000 were Dickcissel 25,300 1976 Hato Masaguaral, Guarico, Venezuela reported on the San Blas count in Tree Swallow 24,847 1989 Belize City, Belize Nayarit, Mexico, on the 1980–81 count California Gull 18,270 1990 Puerto Penasco, Sonora, Mexico (Table 4). Although we previously high- Western Gull 16,393 2004 Ensenada, Baja California, Mexico lighted the encouraging amount of data Redhead 16,000 1997 Rancho Rincon de Anacahuitas, Tamaulipas, Mexico collected, this record shows that sample sizes are still quite small for meaningful Yellow-headed Blackbird 15,000 1981 San Blas, Nayarit, Mexico trend analyses, since this one count of Western Sandpiper 12,743 2005 Ensenada de La Paz, BCS, Mexico

22 AMERICAN BIRDS El Salvador; Table 4). The highest count party hour on the 1994–95 count from for an exotic species was for European New Providence Island, Bahamas). Starling (4317 birds on the 2002–03 Neither of the latter two species was count from Ensenada, Baja, California, among the top 10. [Note: Not all Mexico), but this was not among the top counts reported their effort. Therefore, 10 for all species. the number of birds per party hour used The raw numbers of birds detected can in this analysis was incomplete.] present a misleading picture of regional differences in abundance since the num- ■ Summaries by region and guild bers can be largely dependent on the As one might expect based on geo- number of observers and the amount of graphic proximity, Mexico has reported One of the real treats on a CBC in Central time spent looking. A crude form of the greatest number of the 523 U.S. America is the potential to see a Bare- effort adjustment that has typically been species (489; 93.5 percent), followed by necked Umbrellabird (Cephalopterus used is to simply divide the number of Central America (311 species; 59.4 per- glabricollis), here on the Rain Forest Aerial Tram count this season. birds detected by the number of party cent), the Caribbean and Bermuda (279 Photo/G. Thomas Bancroft hours, as described above (Butcher and species; 53.3 percent), and South America McCulloch 1990). According to this esti- (198 species; 37.9 percent). Of the 175 Table 5. Highest total number of individu- mate of abundance, the count that neotropical migrants, 156 (89.1 per- als reported for species that breed in the reported the highest abundance of a cent) have been reported in Mexico, 154 U.S. or Canada since 1973 for all Latin species was again the 1980–81 San Blas (88 percent) in Central America, 121 American and Caribbean counts combined. count of Red-winged Blackbird (2632 (69.1 percent) in the Caribbean and 112 Species # Birds birds per party hour; Table 6). For (64 percent) in South America. And Red-winged Blackbird 476,841 neotropical migrants, the high count was among temperate migrants, 218 of 227 Cattle Egret 310,945 the 2005–06 count of Western Sandpiper (96.0 percent) have been reported from Great-tailed Grackle 198,955 from Ensenada de La Paz, BCS, Mexico Mexico, and 126 (55.5 percent) have Black Vulture 142,466 (698 birds per party hour). The highest been reported from the Caribbean and Tree Swallow 131,332 count for residents was the 2008–09 Bermuda. Only 97 (42.7 percent) and 47 Brown Pelican 130,330 count of Black-bellied Whistling Ducks (20.7 percent) were recorded from Central American Coot 119,022 from Pachaquiaro, Meta, Colombia (484 and South America, respectively. By def- Brown-headed Cowbird 110,848 birds per party hour); and for exotic inition we would expect this pattern, Laughing Gull 99,781 species, the highest count was for since temperate migrants are those whose Western Sandpiper 98,895 Eurasian Collared-Dove (105 birds per populations spend the nonbreeding season mostly north of the Tropic of Cancer. Table 6. Highest reported number of birds detected per party hour of effort for a single As we reported for the region as a whole, day at a single place for species that breed in the U.S. or Canada. the majority of the most abundant and widespread “migrant” U.S. species that # Birds occur in the Latin America/Caribbean Species per Year CBC Party (Dec.) region are widespread tropical species Hour with local resident populations; and in Red-winged Blackbird 2631.58 1980 San Blas, Nayarit, Mexico many cases, the local resident popula- Rancho Rincon de Anacahuitas, Redhead 1600.00 1997 tions may be more abundant than the Tamaulipas, Mexico migratory U.S./Canadian populations. Rancho Rincon de Anacahuitas, Northern Pintail 1200.00 1997 The migratory vultures and wading Tamaulipas, Mexico birds are examples of this. Moreover, the California Gull 913.50 1990 Puerto Penasco, Sonora, Mexico most widely detected U.S. species on South American CBCs was Tropical Lark Bunting 781.75 2004 Rancho el Palomino, Chihuahua, Mexico Kingbird, which was found on 66 of the West Coast of the Yucatan Peninsula American Coot 733.33 2006 90 circles. This represents a very wide (Celestun), Mexico distribution considering the fact that 18 Western Sandpiper 698.25 2005 Ensenada de La Paz, BCS, Mexico of the South American CBC circles are Dickcissel 632.50 1976 Hato Masaguaral, Guarico, Venezuela in the more temperate austral regions of Brown-headed Cowbird 610.50 2006 Guadalajara, Jalisco, Mexico the continent in Chile, Argentina, Uruguay, and Paraguay. Balboa to Pacheca Island, Pearl Island Black Tern 537.83 1974 Group, Panama continued on page 120

THE 110TH CHRISTMAS BIRD COUNT AMERICAN BIRDS 23 St. Peters 70, Louisbourg 98, and Strait Terrace 98), Bullock’s Oriole 1 (BC, Finch 312 (BC, Vaseux Lake 89), of Canso 106), Bobolink 1 (NS, Halifax Kelowna 92 and 96, and Parksville- House Finch 3020 (ON, St. Thomas [east] 74), Red-winged Blackbird Qualicum Beach 107; NL, St. John’s 89), Red Crossbill 3527 (ON, 10,278 (ON, Long Point 110), E. 108; NS, Strait of Canso 92, Halifax- Algonquin P.P. 95), White-winged Meadowlark 249 (ON, St. Thomas 73), Dartmouth 101, and Halifax [west] 70; Crossbill 8728 (ON, Algonquin P.P. W. Meadowlark 189 (BC, Ladner 110), ON, Woodhouse 81 and Dryden 102; 85), Com. Redpoll 14159 (NB, Cape Yellow-headed Blackbird 3 (NS, QC, Quebec 97), Baltimore Oriole 28 Tormentine 92), Hoary Redpoll 340 Kingston 93), Rusty Blackbird 575 (NS, Halifax-Dartmouth 109). (SK, Regina 72), Pine Siskin 10,420 (ON, Blenheim 85), Brewer’s Blackbird Common Chaffinch 1 (NS, Bedford- (BC, Parksville-Qualicum Beach 104), 6217 (BC, Ladner 61), Com. Grackle Sackville 102; NS, Halifax [west] 89), Am. Goldfinch 2696 (NS, Wolfville 4400 (ON, Wallaceburg 102), Great- Brambling 3 (BC, Port Clements 106), 92), Eur. Goldfinch 2 ex (QC, tailed Grackle 1 (BC, Kelowna 102 and Gray-crowned Rosy-Finch 600 (BC, Longueuil 108), Evening Grosbeak 103, Vernon 94; ON, Long Point 89), Penticton 87), Pine Grosbeak 1847 2621 (ON, Ottawa-Gatineau 73), Brown-headed Cowbird 30,000 (ON, (NL St. Anthony’s 75), Purple Finch House Sparrow 23761 (MB, Winnipeg Guelph 76), Hooded Oriole 1 (BC, 1845 (NS, Broad Cove 92), Cassin’s 90).

A Summary of Christmas Bird Counts in Latin America, the Caribbean, and Bermuda continued from page 23

Of potentially more interest are the Literature Cited Link, W. A., J. R. Sauer, D. K. Niven. 2006. A hierarchi- patterns we find among neotropical Butcher, G. S. 1990. Audubon Christmas Bird Count. cal model for regional analysis of population migrant species that do not have resi- In: Sauer, J. A. & S. Droege (eds.): Survey designs change using Christmas Bird Count data, with dent populations south of the U.S. and statistical methods for the estimation of avian application to the American Black Duck. Condor These are the species for which the U.S. population trends. U.S. Fish Wildl. Serv. Biol. Rep. 108: 13-24 and Canada bear most of the conserva- 90(1): 5-13. Martin, T. E., and D. M. Finch. 1995. Ecology and tion responsibility during the breeding Butcher, G. S. and C. E. McCulloch. 1990. Influence of Management of Neotropical Migratory Birds: A season, whereas their survival depends observer effort on the number of individual birds Synthesis and Review of Critical Issues. Oxford upon the conservation of habitat south recorded on Christmas Bird Counts. In: Sauer, J. A. University Press, New York. & S. Droege (eds.): Survey designs and statistical of the U.S. during the nonbreeding sea- NABCI (North American Bird Conservation Initiative). methods for the estimation of avian population trends. son. This will be the subject of a separate 2009. State of the Birds United States of America U.S. Fish Wildl. Serv. Biol. Rep. 90(1): 120-129. paper in progress. We have good abun- 2009. U.S. Department of Interior, Washington D.C., Faaborg, J., R. T. Holmes, A. D. Anders, K. L. Bildstein, K. dance and trend information for many 36 pp. M. Dugger, S. A. Gauthreaux Jr., P. Heglund, K. A. NABCI (North American Bird Conservation Initiative). of these species on their breeding Hobson, A. E. Jahn, D. H. Johnson, S. C. Latta, D. J. 2010. The State of the Birds 2010 Report on Climate grounds as a result of the U.S. Levey, P. P. Marra, C. L. Merkord, E. Nol, S. I. Change, United States of America. U.S. Department of Geological Survey Breeding Bird Survey Rothstein, T. W. Sherry, T. S. Sillett, F. R. Thompson III, the Interior: Washington, DC. Available from: (Sauer et al 2008). And although we and N. Warnock. 2010a. Conserving migratory land http://www.stateofthebirds.org/pdf_files/State have relatively good information about birds in the New World: Do we know enough? %20of%20the%20Birds_FINAL.pdf. the general nonbreeding distribution of Ecological Applications 20 (2) 398-418. 2010. National Audubon Society. 1973. The Seventy-third these species (Rappole et al. 1983, Faaborg, J., R. T. Holmes, A. D. Anders, K. L. Bildstein, K. Christmas Bird Count. American Birds 27(2): 135-138. Rappole et al. 1995), no survey exists M. Dugger, S. A. Gauthreaux Jr., P. Heglund, K. A. that is sufficient to estimate rangewide Hobson, A. E. Jahn, D. H. Johnson, S. C. Latta, D. J. Niven, D. K., G. S. Butcher, and G. T. Bancroft. 2009. population trends on their wintering Levey, P. P. Marra, C. L. Merkord, E. Nol, S. I. Christmas Bird Counts and climate change: north- grounds. The CBC may eventually be Rothstein, T. W. Sherry, T. S. Sillett, F. R. Thompson III, ward shifts in early winter abundance. American able to meet this need, but until that and N. Warnock. 2010b. Recent advances in under- Birds 63: 10-15. time there is still much to be learned by standing migration systems of New World land birds. Rappole, J. H., E. S. Morton, T. E. Lovejoy, III, and J. L. mining the CBC database. Ecological Monographs 80 (1) 3-48. 2010. Ruos. 1983. Nearctic Avian Migrants in the Neotropics. Hagan, J. W., and D. W. Johnston. 1992. Ecology and U. S. Fish and Wildlife Service, Washington, D.C. Rappole, J. H., E. S. Morton, T. H. Lovejoy III, and J. L. Acknowledgments conservation of neotropical migrant landbirds. Ruos. 1995. Nearctic Avian Migrants in the Neotropics, Thanks to all the count participants, Smithsonian Institution Press, Washington, D.C. 2nd. Ed. Smithsonian Institution, Front Royal, VA. count compilers, and regional editors for 609 pp. Keast, A., and E. S. Morton. 1980. Migrant birds in the Sauer, J. R., J. E. Hines, and J. Fallon. 2008. The North their work in submitting these data. Neotropics: Ecology, behavior, distribution, and con- American Breeding Bird Survey, Results and Thanks to U.S. Fish and Wildlife servation. Smithsonian Inst. Press, Washington, D.C. Analysis 1966-2007. Version 5.15.2008. USGS Service for a grant to complete data LeBaron, G. S. 2010. Online bibliography Christmas Patuxent Wildlife Research Center, Laurel, MD. entry for these counts and to Bill Howe, Bird Count Bibliography of Scientific Articles. Available Sauer, J. R., D. K. Niven, and W. A. Link. 2004. Stephanie Jones, and Steve Lewis for from: http://birds.audubon.org/christmas-bird- Statistical analyses make the Christmas Bird Count advocating for this project within the count-bibliography-scientific-articles. relevant for conservation. American Birds 58: 21-25. Fish and Wildlife Service.

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