Pairing up

Popped into barking bay on my way home from work this evening at about 4.15. The tide was in so i just had a quick scan round the birds roosting on the jetty, l noticed that apart from the gulls and lapwings the rest were in pairs. There were a mixture of gulls including 1 GBB, about 20 lapwing,  2 Curlew 2 Canada geese  2 Oystercatchers (first of the year) and 2 small waders i couldn't I.D as the light was fading and i only had a small pair of bins with me.