2012 NORTHEASTERN NATURALIST 19(4):647–652 Aerial Surveys of the Labrador Coast, 2006: Observations of Marine Bird Distribution and Abundance During the Breeding Season Keith G. Chaulk* Abstract - Very few large-scale studies of breeding marine birds have been conducted in Labrador. To address this information deficit, we conducted near-shore aerial surveys of the Labrador coastline between 6–11 and 21–26 June 2006. Our primary species of interest was Somateria mollissima (Common Eider), for which we counted only adult males. In total, we identified 8 species and 5 species categories (alcid colony, mixed tern and gull colony, etc). In total, we counted 40,700 birds, of which Common Eiders were the most widely distributed species, accounting for 88% of all flock/colony observations. Melanitta perspicillata (Surf Scoter) was the second most abundant species, but had a limited distribution, while Cepphus grylle (Black Guillemot) was the third most abundant species observed, but showed the second widest regional distribution. This information is valuable to resource managers and ecosystem researchers. Introduction Marine birds act as natural samplers of the environment (Charrassin et al. 2002, Parsons et al. 2008), including prey species (Buren et al. 2012) and contmination (Monteiro and Furness 1995), and they provide valuable information to resource managers with respect to ecosystem change. The Labrador coast is an important sub-arctic region for many species of breeding marine bird (i.e., coastal waterfowl and seabirds). However, in the last several decades, only a few large-scale aerial marine bird surveys have been conducted during the breeding season (Chaulk 2009; Lock 1986; S. Gilliland, Canadian Wildlife Service, St. John’s, NL, Canada, unpubl. data). Consequently, there is little current information about the biodiversity, spatial distribution, and relative abundance of breeding marine bird species in Labrador during this important phase of their life history. Furthermore, the coastal region of Labrador is experiencing increased industrial activity, including shipping, tourism, and oil and gas exploration. Any information on the current state of the marine environment could prove extremely useful for ecosystem-monitoring purposes should these industries continue to expand their operations in the region. Our survey was designed to address deficits in our understanding of regional breeding marine bird distribution and abundance, and provide information that will be valuable for environmental assessment, resource management, and ecosystem and climate-change monitoring. Methods We flew aerial surveys on the Labrador coast from 6–11 June and 21–26 June 2006, which aligns with the start of the regional breeding season for many *Labrador Institute, Department of Biology, Memorial University of Newfoundland, Box 490, Station “B”, A0P 1E0, Goose Bay, Labrador, NL; keith.chaulk@mun.ca. 648 Northeastern Naturalist Vol. 19, No. 4 breeding marine birds. The southernmost point of the study area was Fish Cove Point (54.17°N, 57.34°W), and the northernmost point was Cape Kakkiviak (60.05°N, 64.20°W); the latter is about 30 km south of Cape Chidley, Labrador (Fig. 1). Our primary species of interest was Somateria mollissima L. (Common Eider), for which we counted only adult males. We targeted adult males due to their white plumage, which made identification and detection much easier. However, we also recorded other species, especially when they were present in large flocks or colonies. For these other species, we estimated the numbers of total birds observed. Surveys ceased on 11 June 2006 because the only aircraft available in the region required maintenance. This break in coverage occurred at the Solomon Islands (55.85°N, 59.94°W; Fig. 1). Sea ice was absent from all survey areas, except north of Port Manvers (56.97°N, 61.45°W), where the ice cover after 21 June was less than 10%, and the ice did not impinge upon the islands or coastline surveyed. During the surveys, wave heights were generally less than 1 m. From Fish Cove Point to Port Manvers, detection probabilities were high due to light winds and good visibility. North of Port Manvers, both weather (winds regularly exceeding 15–20 knots with stronger gusts) and terrain (high prominences and deep valleys) prevented survey of the mainland shoreline, especially in the many long fjords. Consequently, this section of the study area was limited to the outer islands, possibly leading to fewer detections/observations of marine birds. The study team consisted of three observers, including an observer/recorder in the co-pilot seat, the pilot/observer and a rear observer/photographer. We used a Britten-Norman Islander, a high-wing, twin-engine, piston-driven aircraft. The plane had extra fuel tanks in its wing tips allowing approximately 4:45 hrs in Figure 1. A map of the general route flown during the aerial seabird survey (dashed black line) conducted in Labrador, Canada during June 2006. Note that the actual survey route followed the mainland and archipelago shoreline which, owing to its complexity, was estimated to be approximately 11,513 km in length. 2012 K.G. Chaulk 649 the air before refuelling. Our flight altitude was approximately 150 m above sea level, while flight speeds were approximately 185 km/hr, although down-wind speeds occasionally reached 220 km/hr. The flight track followed the coastline, both mainland and island, which were surveyed with equal intensity. This method was employed to increase comparability with previous aerial surveys by Lock (1986) and S. Gilliland (unpubl. data). The mainland and island shorelines were complex and convoluted, containing many small bays, bights, inlets, and islets. Upon survey completion, the GPS odometer registered a total survey track of 11,513 km. Marine bird observations, including colony locations, were recorded to an accuracy of approximately 500 m either side of the aircraft track. Coordinates were recorded in decimal degrees NAD 83. To record our observations, we used the USFWS GPS voice-recording software, which links audio data to GPS location (Chaulk and Turner 2007). We used a DELL laptop running WINDOWS 1995, and our GPS device was a Garmin III plus. For navigation, we used a separate Garmin GPSMAP 276C (color) which contained the 1:50,000 digital topographic map series for Labrador. The latter was most useful for confirming areas over-flown on the first pass, particularly in areas with complex coastlines where navigation was difficult. Results In total we recorded 40,700 marine birds represented by 13 species categories (Table 1, Fig. 2). Male Common Eider accounted for approximately 46% of all individuals and 88% of all flocks/colonies observed. Eiders were absent from most of Lake Melville except east of approx. 58.95°W. Melanitta perspicillata L. (Surf Scoter) and Cepphus grille L. (Black Guillemot) represented 12.5% and 11.7% of all observations, respectively. Scoters were mainly observed in very large flocks near Big Bay (55.71°N, 60.58°W) and near Zoar (56.13°N, 61.38°W). Black Guillemots were typically associated with colonies, but interestingly, were not observed in Lake Melville (Fig. 1). Occasionally, Anas rubripes (Brewster) (American Black Duck) and Branta canadensis L. (Canada Geese) were observed and counted, but not in large numbers (Table 1). Another 1239 unidentified ducks were observed; these species were thought to be primarily a mix of Bucephala clangula L. (Common Goldeneye) and Mergus serrator L. (Red-breasted Merganser) (Table 1). Larus argentatus (Pontoppidan) (Herring Gull) were observed as far north as Nain (56.52°N, 61.68°W). Larus hyperboreus (Gunnerus) (Glaucous Gull) were first observed in the Makkovik area (55.12°N, 59. 05°W) and were consistently observed northwards. Larus marinus L. (Great Black-backed Gull) occurred in all survey regions. Many gull observations, especially of Great Black-backed Gull, were of single individuals (Table 1), and such gull observations were not regularly recorded except during lulls in counts of other species, or when observed in large flocks/colonies. We also counted 745 unidentified terns in 22 colonies; these were thought to be Sterna paradisaea (Pontoppidan) (Arctic Tern) and Sterna hirundo L. (Common Tern), but unfortunately, we could not determine the ratio between the two species (Table 1). We also observed 7 mixed tern and gull colonies with an 650 Northeastern Naturalist Vol. 19, No. 4 Table 1. Total number of individuals and flocks detected during aerial surveys on the Labrador coast during June 2006. SD = standard deviation. Number of flocks Flock and/or colony size and/or Species category Total count colonies observed Mean SD Waterfowl Common Eider 18,681 1914 9.8 25.3 Surf Scoter 5086 49 103.8 102.7 Unidentified duck 1239 16 77.4 113.1 American Black Duck 236 17 13.9 16.3 Canada Goose 50 7 7.1 5.7 Alcids Mixed alcid colony 7705 24 321.0 483.1 Black Guillemot 4750 74 64.2 96.8 Gull and Terns Mixed tern and gull colony 910 8 113.8 118.6 Mixed tern colony 745 22 33.9 57.0 Unidentified gull 699 13 53.8 44.6 Glaucous Gull 366 7 52.3 85.9 Herring Gull 155 8 19.4 22.3 Great Black-backed Gull 78 9 8.7 12.1 Total 40,700 2168 Figure 2. Distribution and abundance of selected species of seabird/waterfowl, summarized by half-degree latitude for an aerial survey conducted in Labrador, Canada during June 2006. The peak count for each species can be found adjacent to the tallest bar. Also note that the scale of the y axis (“Count”) varies by species category. estimated 910 birds in total. The primary gull species in these mixed colonies, based on local knowledge, was thought to be Larus delawarensis (Ord) (Ringbilled Gull). These mixed tern and gull colonies were mainly recorded in Lake 2012 K.G. Chaulk 651 Melville and Groswater Bay, but the ratio between terns and gulls remained undetermined. The northernmost tern colony was observed in the bottom of Voisey’s Bay (56.28°N, 61.88°W). We also identified 23 mixed alcid colonies with an estimated total of 7705 birds. The largest alcid colony (54.32°N 57.08°W), had ≈2000 individuals and the second largest (56.05°N, 60.46°W) had ≈1500 individuals. Unfortunately, we could not determine species composition for any alcid colony, which we assumed contained varying combinations of Alca torda L. (Razorbill), Fratercula arctica L. (Atlantic Puffin), Uria lomvia L. (Thick-billed Murre), and Uria aalge (Pontoppidan) (Thin-billed Murre). Discussion Chaulk (2009) used a subset of the data reported here to assess long-term population trends in Common Eider and reported a significant increase since the 1980s, mostly driven by higher counts in the southern portion of the 2006 study area. We note that in order to compare the current study with Lock (1986), one must truncate the Lock (1986) data set to a southern boundary of approximately 53.50°N and a northern boundary of approximately 60.00°N. For the same coverage area as 2006, Lock (1986) reported nearly 15,000 more Surf Scoter. However, the lower number of scoters in 2006 could be a function of survey timing relative to the timing of breeding and moult migration, since female Surf Scoters moult later than males (Savard et al. 2007). If this was the case, then most females and some males might still have been on the breeding grounds and would not be represented in our counts along the coast. In all areas, local residents reported that the spring of 2006 was then one of the earliest springs in living memory, with ice cover disappearing very early from most regions of the Labrador coast. Ice cover has been shown to influence nesting ecology in eiders (Chaulk and Mahoney 2012). Additionally, there are interspecific differences in breeding phenology, with some species exhibiting substantial annual variation based on environmental factors (Birkhead and N ettleship 1995, Chaulk et al. 2004). It is not clear what effect the earlier spring had on the species we observed, but it is assumed that many individuals were able to nest earlier in 2006 than in a typical year. Based on anecdotal information provided by local hunters, Great Blackbacked Gull are thought to be among the earliest nesters, with some individuals at Lake Melville (Fig. 1) typically commencing nest initiation in early June, or possibly late May. Also at Lake Melville, terns are typically thought to begin nesting in mid-June, though this can vary slightly by year (K.G. Chaulk, unpubl. data). Meanwhile, Common Eider in northern Labrador have been shown to commence laying from mid–late June, with actual dates varying by latitude and ice cover (Chaulk et al. 2004, Chaulk and Mahoney 2012). Birkhead and Nettleship (1995) report median hatching dates for undisturbed alcids on the Gannett Islands (53.93°N, 56.50°W) ranging from 16 July to 10 August 10, with Common Murres hatching earliest and Atlantic Puffins hatching latest. Depending on the species, this could indicate nest initiation commencing between mid-June and mid-July. The largest mixed alcid colonies we observed 652 Northeastern Naturalist Vol. 19, No. 4 were detected on 7 June and 21 June, suggesting that our surveys overlapped with the start of nesting. The unusually early spring in 2006, combined with variation in survey methodologies and the extended cessation in survey coverage during the middle of June, made it difficult to assess how well the 2006 data represented the distribution and abundance of marine birds in the overall region when compared to earlier surveys. For any species other than Common Eider (see Chaulk 2009), the information reported here should be viewed as an index of relative abundance and distribution rather than as a comprehensive census. Even with these limitations, however, our surveys represent valuable baseline information on marine bird distribution and abundance that should be useful to resource managers and to ecosystem and climate-change researchers. These surveys also are relevant for environmental assessment purposes, especially given the expected increases in shipping, offshore oil and gas exploration, and other industrial activities in coastal Labrador. Acknowledgments I would like to thank pilot/observer Rene Geoffroy and observer/photographer Pierre Ryan. Thanks to Morgon Mills for his helpful review of the manuscript and to two anonymous reviewers for their earlier comments. Funding for this survey was provided by the Canadian Wildlife Service. Literature Cited Birkhead, T.R., and D.N. Nettleship. 1995. 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