Cape Spear, Cryptic Thrushes, and the Spirit of Science


DSC03855On 18 Jun, Rinchen and I bid farewell to Jeremy, leaving him at St. John’s where he would catch his flight home to New York the following day. Before we parted, we made a brief visit to Cape Spear, which holds the unique distinction of being the easternmost point in North America. From its rocky coast, we could see the hidden entrance to the St. John’s harbor in the distance, and a number of shipping vessels were coming to and from its sheltered waters. Occasionally, we caught a glimpse of a small whale surfacing several hundred meters from shore, which, from its size and dark color, we surmised was a Pilot Whale (genus Globicephala, presumably G. melas based on range maps). There were a variety of shorebirds visible from the cape, and also several Savannah Sparrows (Passerculus sandwichensis) flitting about the low-lying vegetation, and their delightful tinkling song was heard frequently as we strolled up and around the lighthouse and a nearby WWII-era bunker. I can now say with confidence that the easternmost landbird in North America on June 18, 2015, was this species!

The view from Cape Spear, with St. John's harbor and Signal Hill in the distance.

The view from Cape Spear, with St. John’s harbor and Signal Hill in the distance.

The following day, Rinchen and I drove west to Notre Dame Provincial Park, in the north central part of the island, where we were reunited with our crew-mates Alyssa and Lucy. They had already completed several point count surveys along Route 360, the only paved road that penetrates the vast wilderness of central Newfoundland. We were to continue surveying that route the following day, with the hope (albeit slim) of finding more Gray-cheeks. DSC03971It has been some years since Gray-cheeks were reported from this area, and indeed from most lowland areas of the island, and Alyssa did not detect them during last year’s surveys; but we also need ‘absence’ sites in our dataset for comparison, so it is important to survey them nonetheless. The road is long and wild, lined with a variety of habitats including immense bogs, subarctic tundra, and dense thickets of Alder and Spruce. At our camp, I played my recording of the strange thrush call (see previous post) from Terra Nova for Alyssa, who was intrigued and subsequently searched through a library of field recordings on her playback device (which we did not have access to while the crews were separated). She soon revealed to us that the calls were actually given by a Hermit Thrush – not a Gray-cheek! DSC03918This was troubling to me, because it meant that I had most likely misidentified the bird on Ochre Hill, which to me had looked rather gray and did not bob its tail like a Hermit – but after hearing the call on her device, it seemed infinitely more likely that I was in error than the alternative, that Gray-cheeks were present but not responding to playback, and that they were giving this particular call, that (we now learned) is in the breeding-ground repertoire of its relative the Hermit. Alyssa also played for us a downward tonal call that sounded strikingly like those that we had heard in the field at Terra Nova, and with which I was unfamiliar owing to the fact that my field experience with that species has been more or less restricted to its wintering grounds and migratory stopover sites. Indeed, this call is quite similar to those of the Veery and Gray-cheek, and the birds even seemed to modulate them in a similar manner (i.e., with a varying degree of buzziness and amplitude), causing me even more confusion.

Vegetation surveys with protective gear. The black flies can be vicious!

Vegetation surveys with protective gear. The black flies can be vicious!

Nevertheless, the data that Alyssa presented was enough to convince me that my identification at Terra Nova had been wrong, so we amended our survey data accordingly – the self-corrective mechanism of science at work! Although slightly embarrassing, my blunder was an excellent learning opportunity for me, and I think also for the rest of the crew. One aspect of science that is particularly awesome is that it requires one to be flexible and accommodate new data that emerge. This can be challenging when the data are in conflict with one’s own observations, but the prudent course of action must be to accept the most likely scenario, regardless of one’s pride, because subjective experience is just that – subjective. This is not to say that personal observations are never to be trusted, just that we must be willing to acknowledge that we were misguided when presented with more reliable information. Sometimes our perception is skewed simply because we lack the necessary knowledge to correctly interpret what we are seeing; in this case, the call repertoire of the Hermit Thrush has turned out to be more complex than what I had come to expect from that species having observed it only during the winter and migratory periods. Without data to the contrary, all I had to go on was my experience, until Alyssa played me the very same call on her machine and we could compare them side-by-side.

Lady's Slipper orchid (Cypripedium acaule)

Lady’s Slipper orchid (Cypripedium acaule)

My lack of familiarity with the Hermit Thrush repertoire unknowingly shaped my experience, leading me to misidentify the species in the field; but thankfully, because we work in a group with a collective knowledge that exceeds that of each individual, the relevant data was eventually at hand (thanks Alyssa!) and my small blunder was able to be rectified. Through the process, we all learned a bit more about each other and the birds that we are studying. At its best, science is an exercise in humility; it begs us to abandon rigid conceptions about nature and our place in it, and insodoing, enables us to derive greater meaning from its bounty. DSC03979

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Categories: Evolution, Exploration, Natural History, Ornithology

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