Our hummingbirds’ migration route

We wish we knew for sure!

We’ve been hearing for a long time that migrating hummingbirds have to cross the Gulf of Mexico – a journey of nearly 1000 km – without stopping to eat or rest.  Apparently, theybuild up fat reserves, doubling their weight from 3 g to 6 g, and those fat reserves are supposed to enable them to make the crossing overnight without needing to eat on their trip.  So, if all weather conditions are favourable, the hummingbirds would arrive on the northern coast of the Gulf of Mexico about 14 to 16 hours later.

Well, it’s a theory!

Some individuals must do this, but the overall hypothesis is not supported by hummingbirds’ non-random travel habits, moving from food source to food source.  So then we must attempt to prove that most of them go around the vast expanse of water, flying through Texas into Mexico and on to Central America.

The only way to prove that is by having a certain number of banded birds that make the journey and are recaptured at the ends of the route.  Part of the Projet colibris is intended to provide migration data, but it’s not a simple task. 

Since banding first began early in the last century, some 103,000 Ruby-throated hummingbirds across the species’ territory have been banded.  Of that number, very few (less than 100) have been recaptured at locations other than the site of their first capture. 

In spring 2007, a banded female was captured in Saint-Denis-de-Brompton, in Estrie;  she had come from Houston, Texas – a distance of 2750 km. In spring 2009, a banded male was captured in Berthier-sur-Mer; he had come from Nacogdoches, Texas – a distance of 2660 km.  There’s a first piece of data in support of our hypothesis, and it encourages us to continue. 

I had the idea of mapping the few established instances of individual birds travelling a sizeable distance from their point of departure.  The data comes from the Bird Banding Office of the Canadian Wildlife Service’s Migratory Bird Populations Division, and from hummingbird banders’ forums across Canada and the US.

And here’s what came out!  There’s a definite trend!

You’ve got to admit, it does look strangely like the migration route of the Monarch butterfly.