The Dunlin, the bird that shouldn’t be on Bonaire!
With only one prior confirmed sighting in all of Bonaire’s eBird-watching history, the Dunlin which recently visited Bonaire was a very rare vagrant.
Posted August 18, 2024
The Dunlin is not known to migrate through or make rest stops in the Caribbean.
Birdwatching offers an unparalleled connection to nature, requiring both patience and keen attention to detail. Recently, I began a birding session with a drive along one of Bonaire’s shorelines. I stopped to use my binoculars when I encountered some small birds, and I never made it any further!
Two hours later (remember patience is required), I left my special bird, a Dunlin. Had I not known what field marks to look for when I picked up my binoculars, there is a very high probability I would have gone merrily on my way, without even realizing I was seeing a very rare vagrant to Bonaire!
The Dunlin stands out among the myriad of avian species, as it is not known to visit the Caribbean on its migration journeys. Instead, it will travel as far south as Mexico or the southern shorelines of the United States, but it has hardly been encountered as far south as Bonaire. This blog post delves into the meticulous identification of a Dunlin based on specific field marks, behaviors, and comparative analysis with similar species.
Anatomy of a shorebird identification: The Dunlin
Size and structure are key indicators.
The primary factors in identifying a Dunlin are the bird’s overall size, the color and shape of the bill, and the length of the wingtips. The Dunlin observed was significantly larger than the nearby Least Sandpiper, which provided a useful size comparison. Dunlins are generally plump with a characteristic hunched stance, distinguishing them from other shorebirds.
Detailed field marks.
The observed Dunlin exhibited several distinctive field marks:
Legs and bill.
The legs were black and the bill was entirely black, slightly decurved with a thick base, and it had a noticeable droop at the tip. The bill’s length is a crucial feature differentiating it from other similar shorebirds.
Wingtips and tail.
The wingtips extended nearly to the end of the tail but did not exceed it in length. This very specific detail helps rule out other species where the wingtips extend beyond the tail.
Underwing coloration.
The underwings were predominantly white, with some dark mottling along the leading edge and a narrow dark band along the trailing edge.
Foraging behavior.
Behavioral observation is a critical aspect of bird identification. The Dunlin was seen foraging using a probing motion reminiscent of a sewing machine. This up-and-down motion is typical of Dunlins as they search for food just below the surface in the mudflats and shorelines.
Vocalization.
The Dunlin vocalized once during the observation, emitting a raspy “kree” call. Vocalizations can be incredibly helpful in bird identification, providing additional confirmation of the species present.
Exclusions of similar species.
Several similar species were considered but ultimately excluded based on key differences:
- Western Sandpiper: Although similar in appearance, the Western Sandpiper was excluded due to the Dunlin’s larger size.
- White-rumped Sandpiper: This species was also considered but ruled out because the wingtips of the observed bird did not extend beyond the tail. Additionally, the bill of the White-rumped Sandpiper is typically shorter, and a reddish area at the base of the bill was not observed in the Dunlin.
Substantiating data and historical context.
The sighting of a Dunlin on Bonaire at any time of year is remarkable because they simply do not normally fly this far south. However, seeing a Dunlin in early August is even more unusual, given that they are usually late fall migrants and habitually do not leave their northern breeding grounds until September.
However, historical records provide some substantiating context for this observation:
• According to “Birds of Aruba, Bonaire, Curacao” (Wells, Childs Wells), J. Ligon reported (not confirmed) a Dunlin in basic plumage on August 31, 2003.
• Two other sightings (also not confirmed and reported in basic plumage as well) were recorded on June 4, 1985.
• The eBird database confirms one prior sighting on Bonaire on September 25, 2016, observed by the BirdsCaribbean team.
Confirming the Dunlin Identification.
Patience and attention to detail are key in accurately identifying bird species. When submitting a rare bird sighting to eBird, your report will be flagged for human review. To aid in this review process, providing as much detail as possible—such as a detailed description, images, and/or sound recordings—will help confirm your observation.
In the case of this vagrant Dunlin, confirmation was made possible through careful observation and documentation of characteristics such as size, bill shape and color, wingtip length, plumage, behavior, and vocalization. The exclusion of similar species was achieved through specific morphological comparisons. Additionally, historical records supported the occurrence of Dunlins in Bonaire, despite it being outside their typical southern range and usual migration period.
This example highlights the importance of meticulous documentation and careful comparison with similar species for accurate avian identification. Whether you’re an experienced birder or just starting out, understanding these nuances can greatly enhance your birdwatching experience and contribute to citizen science initiatives. Happy birding!
(Images courtesy of the author.)
Dunlin
(Calidris alpina)
Diet: Aquatic invertebrates
Breeding: Typically four eggs are laid and are incubated by both parents
Status: Least Concern, but the population is diminishing
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About the author:
Susan has been living on Bonaire for over 30 years. She is a certified bird guide, as well as a topside and underwater photographer. She is a 2016 graduate of the Caribbean Birding Trail Interpretive Guide Course conducted by BirdsCaribbean.
Get in touch with Susan
Contact Susan via email, Facebook Messenger, call Susan or use the online form below.
If you have any questions about your Bonaire birding tour, feel free to contact Susan for answers. She is always willing to go into more detail about routes or the best times for a tour based on your personal preferences. Tours can be tailored to your interests, whether that be birds, photography, or both!
It is also a good idea to do some homework on the birds of Bonaire before you come. Knowing a little about the birds you might encounter on your tour will make your experience even more enjoyable!
Be sure to check out these resources for birding on Bonaire. Also, reading the Bird Blog will introduce you to the birds that might be observed on Bonaire.
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