New Historical Record: Nova Scotia's 2nd Rock Wren

Field Encounter
On May 12, 2012, I had snapped a few photos of a wren (Fig. 1) in our Pubnico, Yarmouth County, backyard. It was an extremely rare Rock Wren, but at the time I thought it was a House Wren. I had just recently caught the birding bug and the excitement of the April 2012 fallout was still in the air. Blue Grosbeaks, Rose-breasted Grosbeaks, Indigo Buntings and even a Yellow-throated Warbler took residence in my yard following the passing of a deep, slow moving low overnight on April 22 that had produced strong winds from the Caribean and the Gulf of Mexico up to New England and Nova Scotia. The event's weather was summarized by Ian McLaren in an NS-RBA post and also treated more completely in Nova Scotia Birds Vol. 54 No. 3 pp. 42-44. Was the appearance of this wren related to this weather pattern?

Figure 1. Rock Wren in Middle West Pubnico, Yarmouth County, on May 12, 2012. Photo by Alix d'Entremont.

Identification
On May 26, 2016, David Bell was reviewing historical eBird records for Nova Scotia when he came across my photos of the wren. I had just started birding back in 2012 and had found what I thought was the closest match to this bird in the bird books. I called it a House Wren, which was also somewhat rare in Nova Scotia. He explained to me that this was a far rarer species, a Rock Wren and only the second ever for the province of Nova Scotia as per McLaren (2012). Once I took a second look, now with more experience, It was fairly obvious that this was a Rock Wren.

The features that distinguish this bird (Figs 1, 3 & 4) from House Wren (Fig. 2) are its longer bill, bold and extensive supercillium, dark legs, overall dull and more grayish plumage, buffy and un-barred flanks and shorter tail in relation to overall body size.

Figure 2. House Wren at Cape Forchu, Yarmouth County, Oct 9, 2014. Photo by Ervin Olsen.

The following are a few more photos of the Rock Wren.

Figure 3. Rock Wren in Pubnico, Yarmouth County, May 12, 2012. This angle shows the long and lightly decurved bill, the grayish brown upperparts, the unstreaked breast and the buffy flanks. Photo by Alix d'Entremont. 

Figure 4. Rock Wren in Pubnico, Yarmouth County, May 12, 2012. Notice the buffy tips of the outer tail feathers, the long bill and strong supercillium. Photo by Alix d'Entremont

Range & Migration
This wren breeds in the west from Middle America to southern British Columbia, Alberta and Saskatchewan. At present time, very little information regarding Rock Wren migration is available. Overall, it appears as though this species is a short-distance partial migrant. Most individuals from the northern part of the range as well as from higher elevations move southward during autumn. Spring migration takes place between mid-March and early May. (Lowther, Kroodsma & Farley 2000)

Vagrancy
Due to this species' limited migration, extralimital records are few, however occurances in the north east of North America have occured in Minnesota, Ontario, Massachussetts and Nova Scotia. It has also been observed in Louisiana, Alabama, Florida, Viginia and New Jersey. (Lowther, Kroodsma & Farley 2000).

The only previous record for Nova Scotia was of a bird found by John Kearney and Nancy Blair on Seal Island on Oct 4, 1980 that is recorded in Nova Scotia Birds Vol. 23 No. 1.

How did this bird get to Nova Scotia and when did it arrive? These are difficult questions to answer considering the lack of knowledge about Rock Wren migration. There are no other mentions of Rock Wren in the east in the spring 2012 issue of North American Birds, so the arrival of a bird in Pubnico was not part of a larger phenomenon. Was this a case of an initial orientation mistake made by the wren combined with the deep low pushing birds from the Gulf of Mexico up the Eastern Seaboard directly to Nova Scotia?

Ian McLaren in Nova Scotia Birds Vol. 54 No. 3 suggested that the majority of the Indigo Buntings that made it to Nova Scotia likely crossed the Gulf of Mexico during the evening of April 22 to be found from Brier Island to Halifax County on April 24. Did the Rock Wren come with the buntings or did it arrive later? Does the species use leap-frog migration where the most northerly breeders migrate the furthest south?

There are many questions but I've found few answers.

Acknowledgements
I would like to thank David Bell for his sharp eyes and identification skills which have provided me with another life bird for Nova Scotia.

References
Lowther, Peter E., Donald E. Kroodsma and Greg H. Farley. 2000. Rock Wren (Salpinctes obsoletus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/486
doi:10.2173/bna.486

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