How to Get Rooftop Nesting Under Control

Mar 5, 2021

Gull nesting season is fast approaching – with only a couple of months left before the first eggs are laid.

Why is this a problem? With Great Lakes colonies numbering in the tens of thousands, gull nesting grounds need a lot of real estate. As natural nesting areas are replaced by human habitation, buildings, and parks, gulls have to get creative to find the right spot. This can lead to a rooftop nesting disaster.

Gulls Nesting on Rooftop

Gulls are generally ground nesters but also look for areas that let them avoid predators, including islands and cliffs.  In that line, humans have invented the absolute best of both: large flat rooftops. To a gull, these roofs, especially if they are green or gravel roofs, look like islands surrounded by cliffs, a haven where their eggs and chicks will be safe from predators.

Gulls on Rooftop

While a seemingly ideal adaptation for gulls, rooftop nesting creates significant issues for a buildings’ human residents. Large colonies create a lot of messy and acidic droppings. These can spread diseases to humans through rough HVAC systems and can also damage the roof structure as they accumulate and corrode roofing materials.

Gulls bring grass, mud, bones, sticks, and other material onto the roof to eat and build their nests. Along with the vast quantity of feathers they shed, this leads to a huge mess that is more than unsightly. To top it off, gulls are extremely aggressive towards intruders in their nesting territory, especially maintenance workers who need regular access to the roof.

Once the eggs hatch, gulls that worked together to protect the nesting ground may start attacking and even killing each other’s chicks to make sure there is more food and space for their own. Young gulls that can’t yet fly will jump off the roof to escape, often getting injured or dying on the property. Those that survive are still at risk. They often get hit by vehicles or starve. The scavengers that arrive to take advantage of the carnage increase the risk of zoonotic disease transmission to people using the building.

Gull Swarm

The good news is that there are plenty of good options for convincing a colony to move. An integrated management plan uses biological, behavioral, and structural deterrents to help keep your property clean and healthy.

Biological

Ring-billed and herring gull colonies are growing exponentially in the Great Lakes region. Their adaptability to utilizing human structures, readily available sources of human waste food for birds that will eat nearly anything, and the fact that humans don’t tolerate large predators in urban areas leads to very successful nesting and high survival rates. These exploding populations are out of balance with the habitat. Controlling population growth by managing nesting through licensed and permitted Egg Depredation will not only create an overall more harmonious relationship between wild gulls and people, but also has the added benefit of creating an “unsuccessful season.” When an entire colony is unsuccessful in a location, they will sometimes decide to move the whole colony elsewhere, hopefully to a more natural environment.

Behavioral

Since the absence of predators is a big part of a rooftop’s appeal, introducing “predators” into the situation can quickly change the gulls’ intentions. Autonomic laser systems give the appearance of a scary thing constantly moving around the rooftop. Border collies trained in rooftop bird management introduce a “real” predator that will stalk and chase the birds away from the site, making them feel hunted and demonstrating that the rooftop is not a safe place to nest.

Dog Chasing Gulls

Bird Control Laser

Structural

Preventing the birds from accessing or being comfortable on the rooftop is a key component for management and often a required step before permits for nest removal are allowed. Structural deterrents and exclusions such as grid systems, shocktrack, bird spikes that make perching impossible or Eagle Eyes that make landing areas hard to see can all provide excellent long-term results as part of a successful management plan.

Structural Bird Deterrents

An integrated program incorporating all three types of deterrents is the best practice, but has to be started at the right time for best results. Once eggs are laid, behavioral and structural deterrents will be significantly less effective and once eggs hatch there is little that can be done until the young can fly. Permits take time to get approved and work needs to be planned. Contact us today to get started protecting your rooftop from a gull invasion!

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