The conservation group believes that plans for 7,850 new homes in North Somerset place bat colonies at risk.
The Trust believes that the scale of development, which includes the creation of four new communities, could result in the loss of feeding habitats and travel corridors for Greater Horseshoe bats and that links between breeding and hibernation sites could be cut.
The North Somerset Levels provides an important habitat for these bats. It provides access to the insects they eat along with winter hibernation sites.
The Joint Spatial Plan documents promise to help protect these bats and enhance their habitats, though the Trust says it is yet to show the development prevents significant damage to the bats.
"We support the strategic approach to identifying sustainable locations for housing," says the Trust, "but we are calling on the local councils behind the plan to look more closely at the potential impacts on bats in North Somerset and review whether it is possible to go ahead with planned levels of development in the proposed locations without unacceptable impacts on the natural world."