He's referring to a tall pinkish shorebird with a crooked snout.  He points to the grasses near the shore, "there is a hawk out there," he says.  "We think he is a Harrier Hawk.  He dive bombs you when you try to go back to the shore."

The woman says, "the avocets dive bomb you as well, during this season.  They are protecting their nest.  But they let out a sound that mimics the...what is it, honey?"

"The doppler effect," he says,  " As they attack you, the pitch of their chirps changes.  It makes it sound like they are coming at you faster than they are."

They tell me that while an avocet lays her eggs, they are in a trance-like state, and you can get very close to them.  They tell me to walk a mile down the shore to see them in their giant nests. I part ways with the couple, walking on the dry mud until the light gives out, and then I turn back. 

The inn is out of my price range, but the manager had cooked me up some chicken, and offers me a reduced rate and a bottle of wine.  I am relieved, because it could be a few more hours to the next hotel.  I open the bottle of wine and sit on the patio. 

The couple, still strolling, ask me about if I was dive bombed.  I said no, thinking, do they expect me to be thrilled by such a possibility? 

I offered for them to join me on the patio, so I opened my free bottle of wine and poured them some.  The whole time, I'm thinking: what makes people become so obsessive?  They opened their bird book and showed me what they had seen this time, last time, that other place.  He showed me his binoculars.  I wondered whose passion this really was.

"We got into it together," she said.

"But we're not like those crazy birders who compete for the most birds seen."  In a year, in a month, in a state, in a country, or in a region, such as North America, birders 'count' their bird sightings competitively.  Some birders will spend millions to fly around a continent, competing with similarly aggressive birders for an unofficial title.

"This is what I don't get," I say.  "How can you judge how many birds somebody saw?  Couldn't they just lie?"  I am wondering about this more because of my interest in travel writing.

"Ah yes," the man says.  "But there is a system of credibility in place.  These birders take laborious notes.  They strive to make their sightings known. They are often at a birding site at the same time as others. There is some proof."