Sunday, December 31, 2017

2017 Year In Review - The Rarities

I've been spending more time writing for our magazine Nova Scotia Birds, so between that, work and birding, I haven't had the opportunity to publish very many blog posts this year. If you aren't already a member of the Nova Scotia Bird Society, I encourage you to join and have a look at the magazine. There are 4 issues per year and it provides a summary of the season's birds in Nova Scotia.

I was able to add 71 new species to my World life list and 12 of those were additions to my Nova Scotia life list (now at 325). My NS life list was augmented by 36 species in 2014, 22 in 2015 and 13 during 2016, so another 12 this year isn't bad. My NS year list for 2017 ended up at 278, my highest yet - respectable for someone with a full-time job.

Birding highlights of the year were seeing two long-overdue breeding species in NS - Black-backed Woodpecker and Spruce Grouse; finding a large portion of the missing Roseate Terns from North Brother; surveying an island with an estimated ~6000 Leach's Storm-Petrel burrows; participating on a pelagic trip to an area 220 km south of Nova Scotia, east of Georges Bank with 25 Degree Celsius waters; finding a Swallow-tailed Kite, LeConte's Sparrow and Golden-winged Warbler; birding in a 'fallout' in late October; and seeing and audio recording Nova Scotia's first Tropical Kingbird.

When you're a birder, there is always something to look forward to. I'm particularly interested in what the Roseate Terns of Yarmouth County will decide to do. Will they abandon North Brother entirely? Will they make Gull Island their long-term home? I plan on surveying for Leach's Storm-Petrels on Pearl Island and possibly islands near Canso and on Cape Breton Island. I'd like to search for Black-crowned Night-Heron breeding evidence in the Mud Island chain, where I've seen them on multiple occasions. I want to make the trip to Seal Island in my boat (28 km from Dennis Pt Wharf), but I'd only go if there were at least another boat going just in case something goes wrong. The Duffy Rd marsh in Saulnierville looks like a great place for rails, so checking it this spring is a priority.

Below is the list of Nova Scotia life ticks during 2017, self-found birds are annotated with an asterisk (*):

1. Prothonotary Warbler
2. Franklin's Gull
3. Black-backed Woodpecker *
4. Swallow-tailed Kite *
5. Long-tailed Jaeger
6. Audubon's Shearwater
7. LeConte's Sparrow *
8. Tropical Kingbird
9. Yellow-throated Vireo
10. Golden-winged Warbler *
11. Cave Swallow
12. Spruce Grouse *

Here are some photos of the rarities that I was fortunate to see during 2017:

Red-shouldered Hawk at Pleasant Lake, 22 Jan 2017.
Greater White-fronted Goose in Yarmouth, 22 Jan 2017.
Pink-footed Goose in Yarmouth, 22 Jan 2017.
Thayer's Gull in Pubnico, 4 Feb 2017.
Eastern Bluebird in Chegoggin, 21 Feb 2017.
Kamchatka Gull in Meteghan, 1 Apr 2017.
Franklin's Gull in Wolfville, 14 Apr 2017. A fabulous find by Jake Walker.
Field Sparrow on CSI, 17 Apr 2017. Thanks Johnny Nickerson!
Prothonotary Warbler in Pubnico, 18 Apr 2017.
Gray-cheeked Thrush on Cape Sable, 7 May 2017.
Scarlet Tanager in Brighton, 8 May 2017. Thanks Joan Comeau!
Swallow-tailed Kite near Argyle Head, 11 May 2017. Click here for the blog post about this bird.
Blue-gray Gnatcatcher on Bon Portage, 13 May 2017.
Laughing Gull at Chebogue Pt, 17 June 2017.
Long-tailed Jaeger near Georges Bank, 5 Aug 2017.
Audubon's Shearwater near George's Bank, 5 Aug 2017.

Yellow-crowned Night-Heron in Pubnico, 26 Aug 2017.
Lark Sparrow at Chebogue Point, 15 Sep 2017.
LeConte's Sparrow on John's Island (on of the Tuskets), 10 Sep 2017.
Tropical Kingbird at Chebogue Pt, 24 Oct 2017.
Yellow-throated Vireo on Bon Portage, 28 Oct 2017.
Yellow-throated Warbler on Bon Portage, 28 Oct 2017.
Indigo Bunting on Bon Portage, 28 Oct 2017.
Yellow-billed Cuckoo on Bon Portage, 28 Oct 2017.
Hooded Warbler on Bon Portage, 28 Oct 2017.
Golden-winged Warbler at Chebogue Pt, 31 Oct 2017.
Cave Swallow at Chebogue Pt, 11 Nov 2017.

Monday, August 7, 2017

Audubon's Shearwater in Nova Scotia

Field Encounter
The two best birds seen during the recent pelagic trip out of Pubnico were two Long-tailed Jaegers and an Audubon's Shearwater, but the latter was only confidently identified two days later. A small black and white shearwater was seen at 8:09 am on August 4, 2017, in 26-27 degree Celsius, 2 km deep, waters south of Browns Bank (Fig. 2). It flew off as we approached and landed nearby; another approach allowed more photos, and then the bird was off for good. In all, the encouter lasted about 3 minutes and 23 seconds.

Figure 1. Audubon's Shearwater south of Browns Bank, Nova Scotia, 4 August 2017. Photo by Alix d'Entremont.

Some of the birders looked through their binoculars while others (including me) madly snapped away at it with their cameras. We knew full well that Audubon's was a possibility, in fact that species was one of the main reasons for making the trip. There was a short discussion about the bird once it disapeared. Manx and Audubon's Shearwaters are quite similar and some noted the appearance of dark undertail coverts while others mentioned that they had seen more extensive white on the face than on the typical Manx. The images of the bird on the LCD screens on the back of cameras seemed to show that the bird had white undertail coverts. Other birds were to be seen, so the group decided to leave it as a probable Manx.

Figure 2. This sea surface temperature map is modified and rectified from a map from the Rutgers Coastal Observation Lab, shows the location of the Audubon's Shearwater sighting as a yellow "X". The map is from 5 am local time, and is the map whose time stamp is closest to our observation at 8:09 am. I assume that the blue area n.w. of the sighting is an error since the water temperature stayed warm as we made our way through the area.

A more detailed look at the bird and a conclusion as to its identification was done on August 6, 2017, by Mark Dennis upon seeing photos that Richard Stern had posted to Facebook. The word was spread that we had in fact photographed one of the megas that we had hoped to see.

Audubon's is slightly smaller than Manx and has short and broad wings, and a longer tail (Howell 2012). The relative tail length can be seen in Figs. 3 and 4. Figure 4 shows how the tail feathers project farther past the undertail coverts in Audubon's. Howell (2012) states that Manx's upperparts are slaty-blackish relative to the browner upperparts shown by Audubons; this is visible in Figure 3.

Figure 3. Audubon's Shearwater south of Browns Bank (L) and Manx Shearwater on German Bank (R). This comparison shows how the tail tip in Audubon's falls farther past the primary tips than in Manx. Photos by Alix d'Entremont.

The wing shape of the bird in question is difficult to appreciate due to its current stage of wing moult, but the wings do appear less pointed and relatively shorter (Fig. 4). Howell (2012) describes how the undertail coverts of Manx are white while those of Audubon's are "solidly blackish (less common) to extensive white basally (most frequent)". It appears that our recent Audubon's has mostly white undertail coverts except for at least one dusky covert on the right side (Fig. 4). Figure 4 shows how the underwing in Manx often looks whiter overall whereas the underwing of Audubon's had broader dark magins (Howell 2012).

Figure 4. Audubon's Shearwater south of Browns Bank (L) and Manx Shearwater south of Browns Bank (R). Photos by Alix d'Entremont.

Manx is said to be darker-faced with a whitish hook cutting around the auriculars, relative to the whiter faced Audubon's lacking the white hook (Fig 5).  (Howell 2012)

Figure 5. Audubon's Shearwater south of Browns Bank (L) and Manx Shearwater south of Browns Bank (R). Photos by Alix d'Entremont.

Boyd's Shearwater is extremely similar to Audubon's, but has a smaller bill and blueish gray legs (Howell 2012). Our recent bird shows pinish legs and what appears to be too large of a bill for the much rarer Boyd's.

Range and Occurrences in Nova Scotia
The subspecies of Audubon's Shearwater believed to range up to Nova Scotia is lherminieri which breeds in the Bahamas and from Puerto Rico to Tobago. It favours warm waters over the continental shelf slope, often found on weed lines at ocean fronts in the Gulf Stream. It ranges north over the Gulf Stream waters from Florida to North Carolina. It is uncommon to rare north to southern New England (mainly Jul-Aug) and is casual to Nova Scotia. (Howell 2012)

Our first report was of an observation at Western Bank on 7 October 1979 by an experienced birder with few published details. The first fully confirmed and captured by camera was one photographed south of Browns Bank on 17 August 2012 by Tom Johnson. None had been photographed by birders on non-goverment birding trips until our August 4, 2017 record. The list below from eBird, Nova Scotia Birds and McLaren (2012) contains a total of 42 reports, but some of them, especially the early ones, are by a single observer and/or have no photos.

7 Oct 1979 - Western Bank (few published details)
27 Aug 1980 - 30 km s.w. of Yarmouth (few published details)
9 Aug 1992 - 8 km west of Brier Island (details by experienced observer)
4 October 2003 - 175 km s.s.w. of Sable Island (details by experienced observer)
30 Sep 2009 - 240 km s.w. of Halifax (2 ind., details by experienced observer)
17 Aug 2012 - south of Browns Bank (eBird) **FIRST PHOTOGRAPHED**
6 Aug 2013 - 200-156 nm south of CSI (9 ind., Michael Force)
9 Oct 2014 - Seal Island (eBird)
1 Jul 2015 - south of Browns Bank (eBird, no details)
16 June 2015 - 78 nm south of CSI (photographed)
26 Aug 2015 - Bon Portage Island (3 ind., eBird)
30 Sep 2015 - 42.59, -59.00 by ECSAS
1 Oct 2015 - 40.8441, -60.28 by ECSAS (3 ind.)
31 May 2016 - Scotian Slope at 42.75, -61.66 by ECSAS
Summer 2016 - UNKNOWN by ECSAS (3 ind.)
28 Jul 2016 - US cetacean and seabird surveys, 180 nm south of CSI
14-21 Aug 2016 - south of Georges and Browns Banks (11 ind., NOAA surveys)

It is apparent that Audubon's Shearwaters occur May-Oct in warm waters south of Nova Scotia. It is observed infrequently because of the difficulties involved in visiting its extreme offshore habitat.

Howell, S.N.G. 2012. Petrels, albatrosses and storm-petrels of North America. Princeton University Press, New Jersey.

McLaren, I.A. 2012. All the Birds of Nova Scotia: status & critical identification. Gaspereau Press Ltd, Kentville, N.S., Canada

Monday, July 17, 2017

Leach's Storm-Petrels on Little White Island

On July 14, 2017, Keith Lowe and I left by Zodiac from Marie-Joseph, a little village east of Ecum Secum, and made a quick stop at Gull Rock then landed on Little White Island.

Alix d'Entremont (me) holding a Leach's Storm-Petrel on Little White Island, Halifax County. Photo by Keith Lowe.
Again this year I am doing colonial seabird surveys for Environment Canada and wanted to check the islands in the Eastern Shore Island Wilderness Area that were recorded as having the most Leach's Storm-Petrel colonies. Little White Island was last surveyed in 1981 when 616 pairs were recorded.

Location map of Little White Island, Halifax County. Bing Map.
Our anchoring area on the western side of Little White Island. Photo by Alix d'Entremont.

We landed on the western end of Little White Island and found that there were quite a few. Considering the size of the island (350 m by 100 m) and the density of the burrows, we decided to follow the sample method described in Colonial Waterbird Monitoring Program: A Surveyor's Guide previously provided to me by Environment Canada. We sampled 5 areas that were representative of the different vegetation types and slopes on the island. The sample areas were squares with side dimensions of about 4 paces or 3.3 m which equates to an area of 10.9 m². We also noted the general densities to allow for better generalizations of densities by habitat type throughout the island.

Location of Sample 1, short grass, on Little White Island. Photo by Alix d'Entremont.
Below is the field data and key and the data for the 5 samples.

A = Adult
E = Egg
C = Chick
CRE = Can't Reach End
REN = Reached End, Nothing

Sample 1 - Short Grass, slight slope.
44° 53.657' N, 62° 6.093' W
6 burrows (A,E; A; A; CRE; CRE; REN).

Sample 2 - Short Grass, slight slope, near possible fox den.
44° 53.631' N, 62° 6.032' W
0 burrows.

Sample 3 - Tall Vegetation, slight slope.
44° 53.626' N, 62° 5.899' W
0 burrows.

Sample 4 - Short Grass, moderate slope.
44° 53.649' N, 62° 5.871' W
3 burrows (CRE; CRE; CRE).

Sample 5 - Short Vegetation, large slope.
44° 53.660' N, 62° 5.966' W
13 burrows (CRE; A; A; REN; CRE; E; CRE; A; CRE; REN; CRE; CRE; CRE).

Sample 5 had the highest density of all samples and this density of holes appeared to be consistent through the entire north slope. The sample was taken near the middle of the slope both east-west and north-south and was at an entirely random, central location.

The north slope of Little White Island, near the location for sample 5. Photo by Keith Lowe.

I roughly classified the entire island by habitat type in Google Earth and added the sample locations. The burrow calculation for each habitat type was calculated using a burrow density that I chose based on the sample points and the general feeling that I got while walking through the habitat and noting the number of burrows compared to the sample plots.

Sample points and habitat type on Little White Island. Google Earth Export.
Short Grass @ 3,500 m² (3 burrows per 10.9 m² = 0.275 burrows per m²)
3,500 m² * 0.275 burrows per m² = 960 burrows

Short Grass @ 12,500 m² (1 burrow per 10.9 m² = 0.09 burrows per m²)
12,500 m² * 0.09 burrows per m² = 1,145 burrows

Short Vegetation @ 6,600 m² (8 burrows per 10.9 m² = 0.734 burrows per m²)
6,600 m² * 0.734 burrows per m² = 4,844 burrows

Total number of burrows = 6,949 burrows.

Obviously this estimate is simply that - an estimate. Given that there were only two people doing the survey, we weren't able to cover the island in detail, but this at least gives us an idea of the size of the colony. For a more accurate estimate, I would delineate the habitat types and slopes by GPS on the ground and take 4 to 6 samples in each habitat type and slope combination. This should result in a better estimate of numbers.

We did see at least 2 burrows and 1 adult that were predated and a few larger burrows and piles of crushed crustacean shells.

Large burrows and mounds of what appeared to be crustacean shells on Little White Island. Photo by Alix d'Entremont.
Predated adult on Little White Island. Photo by Alix d'Entremont.

The Leach's Storm-Petrel colony on Little White Island was by far the largest that I've ever been to on a grassy island. I have visited Bon Portage that was estimated to have had 50,000 pairs, but it is a wooded island. These storm-petrel colonies are much harder to detect that other colonial birds, so I'm sure there are other large colonies around the province. I hope to get to Indian Island near LaHave in the next few weeks to check for storm-petrels.

Wednesday, July 5, 2017

North Brother Tern Colony Collapse

This isn't all bad news - in fact colony desertion is entirely normal for terns. Read on.

Roseate Terns on the Brother Islands
North Brother Island has consistently been the best location in Nova Scotia to see Roseate Terns for decades. It was home to Canada's largest colony of this rare tern and was one of only a few known breeding locations in Nova Scotia.

Roseate Terns among the Arctic Terns and Common Terns on the Brother Islands off West Pubnico were first identified in 1982 when the Roseates numbered 55 to 60 pairs. The Brothers are two small islands off West Pubnico, Yarmouth County, known locally as "les Îles à Vert". Ted d'Eon of West Pubnico has been monitoring and managing the tern colony since 1983 in cooperation with the Canadian Wildlife Service and the Nova Scotia Department of Natural Resources. Ted's website ( contains years worth of data and photos about his efforts. Due to the Roseate Tern's precarious foothold in Canada, the species depends on management for its survival (Erksine 1992).

The terns used to nest on the two Brother Islands, but since 2003, they only nest on North Brother. The number of Roseate Tern nests fluctuates from year to year with a high of 90 nests in 2002 and a low of 20 in 1991. Fifty Roseate Tern nests were found in 2016.

Roseate Terns are listed as Endangered in Canada under the Species at Risk Act. Its reproductive rate is limited by age of first breeding at age 3, small clutch size (2 for experienced birds, 1 for first-time breeders), and a relatively low survival rate of adults and young birds. One of the main threats to Canadian Roseate Tern populations is predation and displacement of colonies by Herring Gulls and Great Black-backed Gulls. The restricted distribution of this tern makes it vulnerable to localized threats such as human disturbance and weather events. (Environment Canada 2010)

Roseate Tern at North Brother on June 17, 2016. Photo by Alix d'Entremont.

Julie McKnight (Canadian Wildlife Service) holding a Roseate Tern with tiny GPS receiver at North Brother on June 17, 2016. Photo by Alix d'Entremont.

The Brother Islands have been owned by the Province of Nova Scotia since 1990 and have been a Department of Natural Resources (DNR) wildlife management area since 2007. Access to the islands between March 31 and September 1 is not permitted without written authorization of the Director of Wildlife at DNR.

Here is a video that I made in 2011 that shows the boat ride between Abbotts Harbour and North Brother Island, the Roseate Tern management area on North Brother, the eroding island edges and the terns flying above the island. The tern festival mentioned in the video is no longer running.

2017 Breeding Season on North Brother
It all began with low numbers of terns arriving at the start of breeding season. By May 8, 2017, there were only 15 terns above the island in comparison to 100 birds on May 6 of the previous year. It was noted that during the 2016 breeding season, the terns appeared to be more tightly packed than previous years, a product of the yearly erosion to the already tiny island.

A high tide event previous to a visit to the island on May 28, 2017 caused a lot of damage to the "management zone", an area with imported substrate and nesting shelters for the Roseate Terns. By June 4, 2017, it was obvious that the number of terns on the island was drastically lower than in previous years. The nest count of all three species was completed on June 12, 2017, and the results were bad; only 141 nests were found compared to 661 the previous year. This is a loss of more than 500 pairs of terns and the lowest nest count based on data from Ted's website which goes back to 1990.

Roseate Terns nesting in shelters in the "management zone" on North Brother on June 17, 2016. Photo by Alix d'Entremont.

During the June 21, 2017 visit, the number of terns above the island had shrunk to about 30 and most Roseate nests that previously had eggs now did not or were missing an egg and the majority of the remaining eggs were cold. Most of the Common Tern nests were empty and the few Arctic Tern nests that were there, were gone. Four trail cameras were set on North Brother the following day and the photos showed that the predators were a group of 4 American Crows. The colony was now abandoned and for the first time in at least 35 years, there would be no breeding success at all.

Tern Breeding Site Fidelity
Fidelity to natal colony is variable, but usually high. Predation and other causes of breeding failure are known to cause colonies to be abandoned when birds move en masse to other sites, sometimes settling synchronously in contiguous groups. (Nisbet 2002)

The Search for the Missing Terns
On the heels of this year's low nest count, Bertin d'Eon and I searched the Tusket Islands area on June 15, 2017, for the initial missing 500 pairs. A few Common and Arctic were found above Murder Island, Peases Island had 11 nests and Green Island (south of Wedgeport) had 82 nests. The birds found nesting on the Tusket Islands were likely the same that were nesting there in 2016, but a majority simply moved around between islands.

Arctic Tern nest on Peases Island on June 15, 2017. Photo by Alix d'Entremont.
Common Tern nest on Peases Island on June 15, 2017. Photo by Alix d'Entremont.
The newly expanded tern colony on Green Island, June 15, 2017. Photo by Alix d'Entremont.
On June 23, 2017, the Department of Natural Resources flew a helicopter along the coast from Yarmouth to Lockeport in search of the missing birds. Three groups of terns were identified by Pam Mills: 150 individuals in Yarmouth Harbour, 120 in Pubnico Harbour and 30 at Green Island near Cape Sable Island.

Paul Gould, Alec d'Entremont, Florian Schmitt and I searched the islands west of Cape Sable Island on June 25, 2017. A small group of about 32 terns were found on an unnamed island in the Bear Point Thrums group. Our next destination was Green Island west of The Hawk on Cape Sable Island. Four Roseates were seen at Green Island in May 2016, but they were not present during my June 2016 nest survey when I counted 85 nests. Eight Roseates were at Green Island in May 2017, but there were only a few Common Terns left by June 25, 2017. The tern nesting site appeared to have been taken over by Herring Gulls. Later that day, Bertin d'Eon and I counted 27 nests on Île Ferré and none on Île Chespêque, both in Pubnico Harbour. In 2016, there were 30 nests on Île Chespêque, so those birds may have moved 3 km south to Île Ferré.

I am contracted to do tern surveys for Environment and Climate Change Canada with a focus on Roseate Terns, so on June 28, 2017, Bertin d'Eon, Duncan Bayne (DNR Biologist) and I visited Toby Island and Coffin Island in Lunenburg County. There were two Roseates on Toby last year, so it was important to check the island again. We briefly saw one Roseate and similar to the previous year, the bird was never seen again. I assume that the Roseate Terns aren't nesting on Toby since they are not seen returning to the colony once everything calms down from a flush.

Arctic Tern habitat on Coffin Island, Lunenburg County, on June 28, 2017. Photo by Alix d'Entremont.
On July 3, 2017, Calvin d'Entremont and I checked Common Eider nesting shelters on Pumpkin Island near West Pubnico and then followed a Common Tern carrying food from around Bar Island straight to Gull Island. We anchored the boat and then walked onto the island when I heard the distinctive harsh snarl of a Roseate Tern overhead. Once the terns lifted from the colony I was able to count at least 7 Roseates among the hundreds of terns. This was what I had been searching for!

That afternoon, Ted d'Eon, Ingrid d'Eon, Gavin Maclean, Roland d'Eon, Bertin d'Eon and I returned to Gull Island with Ted's boat to do a thorough count of the nests. There were 233 viable nests and an additional 15 or so chicks running around. Most of these terns were new to Gull Island since we only counted 10 nests in 2016. The new terns on Gull Island represent about 40% of the terns that used to be on North Brother. The Gull Island colony is spread along the western and southern edge of the pond. Based on the stage of development of the chicks, it appears that nesting began earlier on the southern edge of the pond. There were many large chicks running around in that area. The northwestern group of nests only had 3 small chicks out of 60 nests. It seems plausible that the birds that never arrived at North Brother in early June nested on the southern side of the pond while another wave of birds arrived and nested on the western side of the pond after the total collapse of North Brother.

Google Maps aerial photo of Gull Island.
Duncan Bayne had told me about how docile the terns were at North Brother this year. That wasn't the case on Gull. They were attacking nearby gull chicks and would hit us in the head, so the tern colony appears healthy. Multiple Common Terns were seen arriving from the north carrying food. This is in contrast to North Brother where the terns were mostly heading south in search of prey.

I was able to get two field-readable leg bands on the Roseates on Gull Island. Both birds were banded as adults at the North Brother colony; one was banded in 2014 and the other in 2016.

Roseate Tern on Gull Island, July 3, 2017. Photo by Alix d'Entremont.

On July 5, 2017, Shawn Craik (Université Sainte-Anne), Manon Holmes (Acadia Univeristy), Nick Knutson (Université Sainte-Anne) and Ben Morton visited Gull Island and were able to get an accurate count of 24 Roseate Terns. They also confirmed two areas where the Roseates appeared to be nesting.

The closest mainland location from Gull Island is the southern tip of Surette's Island which is about 6 km away. It is about 7.5 km away from Abbotts Harbour, where Ted and I typically launch our boats. Gull is the island in Lobster Bay that is the farthest away from all of the others, so should be a good place for the terns. We saw 5 gull chicks on the island and only about 10 gulls around. There were probably more earlier in the season. If we can get a permit to get rid of the gulls early next year, that would be beneficial.

The abandonment of North Brother is the end of an era, but the terns seem to have chosen a great spot to resettle. Gull Island isn't about to become a ledge through soil erosion like North Brother is. It isn't a tall island, but should at least outlast us. We hope to acquire a permit to destroy gull nests next year before the terns arrive. As stated by Erksine (1992), local control of gulls numbers may be unavoidable if we wish to retain breeding eiders, terns or storm-petrels. We provide easy access food to gulls in the form of landfills and fish processing plants which results in unnaturally large populations.

Tern Colony Changes in Southwest Nova Scotia 2016/2017
The nests at most of the terns colonies around Lobster Bay were counted in the last two years, so I thought I'd show the numbers on two maps. The only large colony that was missed is probably the one on Flat Island which are likely mostly Arctic Terns. A majority of the North Brother terns are still not accounted for, but at least the Gull Island colony seems to be doing well. Let's hope that it gets even larger in 2018.

Environment Canada. 2010. Amended Recovery Strategy for the Roseate Tern (Sterna dougallii)
in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada. Ottawa.
vii + 36 pp.

Erskine, A.J. 1992. Atlas of breeding birds of the Maritime Provinces. Nimbus Publ./N.S. Museum. 270 pp.

Nisbet, Ian C. 2002.Common Tern (Sterna hirundo), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America:
DOI: 10.2173/bna.618