For the third time ever, we saw a black-tailed godwit in Switzerland today. Reporting it, I was surprised to see that a black-tailed godwit in Switzerland ranks as a “rare” migrant, but seen regularly, while a bar-tailed godwit would be “very rare”. For 2019, ornitho.ch lists 489 sightings for black-tailed godwit, versus 186 sightings of bar-tailed godwit. (tbh, I find that difference not terribly significant, but I clearly won’t argue with ornitho rarity grades).
The black-tailed godwits spend the winter all over the place, from Australia to the Indian subcontinent and on to western Africa and even some areas in Europe. The Tagus estuary in Portugal is an important site for black-tailed godwit, currently threatened by plans to expand the nearby airport. It should be noted that subspecies tend to favor specific wintering grounds, islandica black-tailed godwits generally stay in Europe, anywhere between Scotland and Spain.
The “blackwits” feed in grassland and muddy estuaries. Their breeding habitat is fens, flood areas at the edge of large lakes, bogs and moorland. While they absolutely do visit coastal areas, they’re also comfortable on inland wetlands.
The black-tailed godwit is the one with the white wing-bars, and long legs protruding beyond the tail.
There are five subspecies of bar-tailed godwits, and their wintering grounds differ. In Europe, we get the lapponica subspecies, which spends the winter along the west coast of Europe and Africa, all the way to South Africa.
The “barwits” are rather specific with their diet, and feed mainly on bristle-worms, with a side-dish of bivalves and crustaceans. Bristle-worms are generally marine, and thus bar-tailed godwits are very much bound to coastal areas due to their diet.
The bar-tailed godwit is the one without wing-bars, but with a longer, more prominent supercilium; the overall impression is similar to that of a curlew.
It’s the food, stupid
Sometimes it’s the migration route (scoters), sometimes the a species tends to migrate in one go rather than taking a break on neutral ground (black storks). In the case of the godwits, the bar-tailed godwit’s diet makes it a much more coastal bird, and thus much rarer in Switzerland than the more farmland-oriented black-tailed godwit.