The first area news story to break as West Seattle Community Garage Sale Day was winding down on Saturday afternoon happened to be a power outage on Harbor Island (original WSB story here). It left us with two followup questions, both of which have just been answered by Seattle City Light: First, a WSB’er asked, how could a Harbor Island outage involve 552 “customers” (since that means individual entities, not people)? SCL’s Mike Eagan explains the outage stretched along East Marginal Way a ways, too. Second, we wondered how just one seagull could cause that kind of trouble by landing on a “transmission line,” and before we could even make a call this morning to ask that, SCL’s Scott Thomsen read our comment and e-mailed:

A bird crashing into a power line would be unlikely to damage the line by the force of the impact. Birds cause outages by creating a new circuit when they touch two different lines. When such a short circuit occurs, it’s the electricity that does the damage by overloading the system. The bird is the connection that allows it to happen. When a bird lands on a single line and doesn’t touch anything else, they’re fine. You see this every day. The reason is that the bird is not creating a new, shorter circuit for the energy. The bird has a higher level of resistance to the electricity than the wire does, so the electricity takes the path of least resistance through the wire.

By the way, City Light’s outage page – including what to do if one happens, who to call, etc. – is here.