How long do seagulls sit on the nest?

Seagull eggs are laid and nested two to three at a time, and it takes about 26 days from laying to hatching. It really depends on the gull species. But for herring gulls, the above guideline is fairly accurate. A very informative website about seagulls can be found at http://www.celestin.com/seagulls/faq.html