Most bird population maps and reference books robins aren't found north of the treeline. The American Robin, whose species is called Turdus migratorius, usually breeds north to Alaska and across Canada south of the treeline. Yet that could be changing, as warmer temperatures in the Arctic open up new ranges for robins. Scientists have noted birds and butterflies moving North in response to warmer weather in Europe and Great Britain. Dhont said that many robins don't migrate at all, but those that do often end up in new environments where they are able to thrive.
Some birds lose their way.
The robins spotted in Iqaluit could have headed North for this reason. Robins were also reportedly seen in Kangirsuk in northern Quebec earlier this year. You might say it's an adaptive mistake. Those birds are more likely to respond to rapid change in the environment. They are more likely to have offspring.