Seagulls making a mess
We have for condo buildings and the seagulls are rusting on the roof. We are wondering how to detour them from landing.
Arenac County Michigan
If you are near Lake Huron, it is difficult to avoid seagulls, especially during the Hexagenia mayfly hatch that occurs every year. Right now, we are rounding out the end of the Hexagenia mayfly hatch in Lake Huron. During that time, it is very common for seagulls to sit on roofs in large numbers near the shoreline because they are stuffed full of mayflies, and they are waiting close to shoreline to have their next feast on mayflies. Once that mayfly hatch subsides, you will likely no longer see them sitting there as much or in that high of numbers. When they no longer have the close abundant food source, they begin to disperse in search of other food. But during the hatch, they stay close and roost in large numbers.
If you do not think it is mayflies, think about another possible source of regular food that is nearby, such as garbage, public parks, etc. If you have no ability to control that problem, then deterring them is your only option. But if this problem has been limited to end of June - early August, it is most likely related to mayflies and should be temporary.
As far as deterring, there are mechanical ways to deter birds, such as making loud noises to regularly scare them off, but those are typically needed repeatedly, especially if mayflies are still abundant, until their food source changes. Some try decoys on the roofs, such as mounted plastic owls, which can sometimes be effective. Commercial buildings sometimes install strips with metal or plastic pokers to deter birds from landing on balconies. I have seen those be effective on London apartment buildings for pigeons. Here are a couple of examples: