Weather plays a dominant role in bird migration, and to a great degree dictates when birds will move en masse to the south or north, depending upon the season. Since the last few days here at the refuge have been dominated by south winds and fog, we have not seen much migratory activity, given that birds moving south will tend to avoid these exhausting conditions. The promise of a fast approaching cold-front, however, gives us reason to be optimistic. Check out the radar signature for the northeast taken from the National Oceanic and Atmospheric Administration’s website this afternoon:
No doubt you can make out the turbulent area in this image, but what isn’t visible in this frame and what follows the frontal boundary are northern winds – perfect if you are a bird in need of a ‘push’ to the south! Hopefully this will translate in to some new arrivals over the next few days, as the front passes over us.
It is also worth noting that large-scale movements of birds show up on weather radar, so the next time you are checking your local weather have a look at the radar signature for your area. Where rain and cloud regularly appear as haphazard or curvilinear signatures, bird movement shows up as pixelated circles:
See http://virtual.clemson.edu/groups/birdrad/COMMENT.HTM for a more thorough treatment of radar ornithology. Very interesting stuff!
In our previous post we discussed the amazing distances some birds cover during migration, which begs the question, just how do they do it? In large part (aside from favorable weather conditions) it comes down to burning fat. Birds moving great distances will become ‘hyperphagic’, which means they will eat like a superbowl fan on Sunday! But instead of sleeping off the largesse of calories on the couch, they utilize that energy to power their epic flights south. Here is a photo of a Red-breasted Nuthatch with a deposit of fat in the furcular hollow (basically the space between the collar bones on you and I). Hopefully you can see the contrast between the red flight muscles surrounding the yellow fat deposit.
Finding abundant resources are a migrating bird’s stock-in-trade, and here at the refuge we are fortunate to have a large crop of blueberries at their peak, which a number of staging Whimbrels have been fattening-up on. Whimbrels are a large shorebird whose winter range includes both coasts from the southern U.S down through South America. Incredibly, this species has recently been found to successfully navigate their way through tropical storms and even hurricanes during their southbound flights over the Atlantic. Though we do not band these birds, we still maintain records of their presence as a corollary to the banding effort.
We never take for granted our beautiful surroundings. Petit Manan Point is part of the Maine Coastal Islands National Wildlife Refuge complex that includes more than 8,000 acres of coastline and offshore islands. Here Jeff samples a portion of this incredible area while scouting for Northern Gannets.