Rarity finders: Cape May Warbler in Co Mayo


Achill Island, situated along Ireland's rugged western coast, has been described by the great Irish naturalist, Robert Lloyd Praeger, as 'windswept and bare'. It certainly is frequently exposed to the powerful forces of the Atlantic but the visiting birder, searching for rare American vagrants, will quickly find out that there is no shortage of trees, shrubs and other vegetation in which migrants can hide. 

Despite increased birder presence in recent autumns, particularly by Josh Jones, Dan Owen and myself, this large island still has received limited coverage. As I'm often the only observer there I focus my efforts at the western end, particularly the area around Corrymore House, which is the first significant patch of cover that birds are likely to encounter if arriving from the west. This has been rewarded by my discovery there of Red-eyed Vireo in 2014 and Baltimore Oriole in 2019.

Baltimore Oriole at Corrymore, Achill Island, 6 October 2019 (Josh Jones).

However, autumn 2023 was not showing great promise. Despite the unprecedented arrival of American landbirds in both Britain and Ireland on the back of Storm Agnes, including the discovery by Josh and Oliver Metcalf of two Red-eyed Vireos on nearby Clare Island, the most unusual migrant I had seen at Corrymore was a Goldcrest. I really felt my luck had run dry but I decided to persist in my daily search for migrants.

The weather on the morning of 29 September was good for seeing birds, with little rain and nice spells of sunshine. There was a moderate south-west wind from which the garden at Corrymore is relatively sheltered by nearby hills. Arriving at 9 am I quickly detected from a distance a small bright yellow-and-greenish passerine high up in the Fuchsia bushes in the front garden. It reminded me of a European Serin but it was clearly a warbler. With its wings drooped I could see its yellowish rump and the dark streaking along its flanks. I immediately knew I was on to an American wood warbler but the big question was which species?

I carefully approached the bird hoping to capture some record shots. As I neared the location where I had first seen the warbler it popped out from a nearby gorse bush and provided brief but excellent views. I was struck by its small compact size, the pale wing panel but no prominent wing-bars and the fine, dark and slightly decurved bill. When it took flight, it revealed very conspicuous white patches on its outer tail feathers. The bird also gave a distinct high-pitched Song Thrush-like tsip call both in flight and when perched. 

Cape May Warbler, Achill Island, September 2023 (Micheál O'Briain).

I quickly checked available identification material on my phone, including The Warbler Guide by Stephenson and Whittle, and came to the conclusion that I was looking at a Cape May Warbler. But this species had never been recorded in Ireland so before making the information public I sent some photos to local expert, Dave Suddaby, as well as to Josh and Dan, all of whom confirmed that my identification was correct. The orange tinge to the yellow on the face suggested that it was an immature male.

Cape May Warbler, Achill Island, September 2023 (Micheál O'Briain).

I was absolutely thrilled. I expect that it's every birder's dream to discover a new species for their country and adding Cape May Warbler to the Irish list was a very special experience for me. I wanted other birders to have a chance to see this beautiful bird as soon as possible. I spread the word online also asking visitors to respect the fact that the bird was on private property. Despite Achill's remote location, about 30 birders from across Ireland got to see it that afternoon.

Cape May Warbler twitch at Corrymore, Achill Island, on 30 September 2023 (Micheál O'Briain).

When it initially arrived the warbler was chased by local European Robins but it quickly established a foraging area which it frequently defended against both robins and tits. It actively fed on insects, at times engaging in short sallies up into the air, reminiscent of a flycatcher. It could also be seen at times probing flowers of both Fuchsia and Escallonia for nectar, behaviour that is apparently facilitated by Cape May having a curled and semi-tubular tongue. The available food supply at Corrymore may also explain why it decided to stay in this location for some time.

During the course of its stay about 150 birders saw this wonderful little bird, including many visitors from Britain. I had notified the landowner's family when I first saw the warbler and I am grateful to him and locals for tolerating this influx of happy birders, who all behaved responsibly. Although it would disappear for periods the bird was not unduly shy and provided spectacular views on many occasions that greatly enhanced the observer experience. It is very likely to have been the most photographed rare bird seen so far in Ireland this year, and went on to linger for 10 days, last being seen on 8 October.

Written by: Micheál O'Briain