Keeping your pool cover clean is a good way to keep smaller animals from running across it or using it as shelter. Small animals may use leaf debris on top of the cover to hide. Cleaning also removes nuts that may fall from a nearby tree that could otherwise be a tempting snack for some animals, like squirrels. 

You can find a variety of humane bird repellent sprays online and at home improvement stores. However, if you want to try a DIY method that will keep birds away without harming them, mix some water, dish soap, and a few drops of peppermint oil and spray the area you want bird-free. Peppermint oil is a notoriously lovely smell for humans, but birds tend to avoid it.

Maintain sealed entry points, use deterrents like spikes or sonic devices, and keep areas clean to discourage nesting.

The best time of year to remove bats is autumn until spring. In fact, many states have restrictions on bat removal, mandating it to start sometime in August and go up until May. For some states, the removal period stops in March. Your pest control pro should know of any restrictions and can help you pick an optimal time for removal.