Hummingbirds' progress is slowed

Ruby-throated Hummingbirds haven't moved much this week along the eastern United States, although they have covered the whole of the Deep South. A surge of colder air from a dip in the jet stream may account for their apparent lack of movement.

As a general rule, the hummingbirds reach the Lehigh Valley around April 15. But weather affects their movement. Cold temperatures, rain and absence of insects and nectar-laden flowers can slow their progress.

It's surprising, though, how quickly they can made up for lost ground if they encounter favorable conditions.

Last year, for example, ruby-throats were seen in southern Virginia, nearly 100 miles north than they are now. However, in 2012, they made their appearance in the Lehigh Valley at about this time. For those keeping track, here is a general year-by-year tally of where the hummingbirds were at this time in March:

2011: Northern Virginia
2010: Along the Potomac between Virginia and Maryland
2009: Southern Virginia
2008: Maryland's Chesapeake Bay region and Cape May, New Jersey
2007: Southern Pennsylvania
2006: North Carolina

Keep in mind that to reach our area, they travel from Central America across the Gulf of Mexico and up much of the eastern United States. Phew! Can you blame them if they need a break to refuel along the way!