Occurrence Maps

American Pipit

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American Pipit is a breeding bird of high tundra habitats, including not only Arctic latitudes, but also in alpine tundra of the Rocky Mountains and Sierra Nevada. Most of the population breeds in Canada and Alaska, and these birds arrive en masse in the United States in October and November. It is a fairly common wintering bird in open country of the western United States.

Perhaps the most valuable aspect of these occurrence maps is that they tend to highlight the regions of the country that are important for a given species at a given season. Most field guide range maps show American Pipits as occurring throughout the southern United States in winter, but few give any indication as to where they are rare, and where they are expected. The winter season maps here highlight the important areas for American Pipit very well. The Central Valley of California, east and south Texas and Louisiana are all clearly important areas for pipits. The Carolinas sustain some during winter on the Coastal Plains, but clearly the likelihood of encountering the species there is much lower. With all the STEM maps that follow, think about these areas of concentration and how they relate to the species’ biology, as well as the potential conservation implications.

Watching the migration is especially fascinating. Note how much earlier the pipits arrive in the western United States than at comparable latitudes in the East. The spring migration of pipits is almost invisible here. Some of this is due to scaling issues, since areas and seasons with high frequency may swamp out those with low frequency. However, it is surprising that there is no obvious signal from spring migration. Are too many birders in the woods in April, with not enough attention to fields? Do pipits move north much quicker in spring than fall? Or is this model somehow missing a significant pulse up the countries midcontinent? If you have ideas, please let us know at the blog!