6. Living with Bats

Theme:	ECOLOGY NETWORKS
Current Topic:	Knapp and Knowle
Thread Title:	Living with Bats
Thread Number:	6 of 7
Learning Focus:	The Knowle in Sidmouth hosts one of Devon's largest Lesser Horseshoe Bat colonies. Learn about the "Bat House" and 2026 conservation efforts.

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How a Devon Redevelopment Became a Hub for the UK’s Rarest Bats

To the casual observer, the former East Devon District Council headquarters—known as the Knowle—is a relic of beige bureaucracy. It is a sprawling complex where the mundane aesthetics of 20th-century office extensions collide with a grand 19th-century villa. Yet, as an urban ecologist, I see a different map entirely. Beneath the drab administrative corridors and behind the weather-beaten fascia boards lies a vibrant nocturnal sanctuary. This site is not merely "empty" office space; it is a "regionally important" biodiversity hub and a critical stronghold for some of the UK’s most threatened Priority Species.

The "Headline" Act: Devon’s Largest Maternity Colony

The crown jewel of the Knowle’s ecological portfolio is the Lesser Horseshoe Bat (Rhinolophus hipposideros). While these bats are rare across much of the UK, the population at the Knowle is staggering in its proportions.

"The Knowle House is famous in the ecological community for hosting what has been described as potentially the largest maternity colony of Lesser Horseshoe Bats in Devon."

The site’s importance stems from its function as a "sustenance zone." During the 2024/25 development planning reviews, ecologists identified a perfect ecological synergy here. The 19th-century villa provides the thermal mass necessary for survival; its thick stone walls act as a heat battery, maintaining the stable, warm temperatures required by hundreds of females to pup and raise their young. Just outside these "nursery" walls, the site’s arboretum and the lush greenery of Knowle Park provide an explosion of insect biomass, offering an immediate and rich foraging ground for lactating mothers.

Architecture as Habitat: From Stone Voids to Wall Cavities

One of the most fascinating aspects of the Knowle is the "niche partitioning" occurring within its walls. Different species have claimed specific architectural features, effectively sharing the building by exploiting its varied construction styles.

While the Horseshoes require large internal voids where they can fly and hang freely, the "urban-adaptable" species utilise the external skin of the more modern office extensions. This creates a hidden layer of life within the very fabric of the buildings.

Where the residents hide:

• Internal Voids and Cellars: Deep, undisturbed spaces within the 19th-century sections, favored by Lesser Horseshoes.
• Wall Cavities: Hidden pockets within modern office extensions that host Soprano Pipistrelle maternity colonies, numbering over 200 individuals.
• Roof Tiles and Fascia Boards: Narrow crevices used by Common Pipistrelles for daytime roosting.

The Soprano Pipistrelles, in particular, rely on the site's proximity to the River Sid. The damp parkland and river corridor provide the high-density forage required to support such a large colony, proving that the building’s value is inextricably linked to the local hydrology and landscape.

The "Whispering Bat" and the Need for Absolute Dark

Within the attic ridge beams of the Knowle House resides the Brown Long-eared Bat (Plecotus auritus). Often called the "whispering bat" because its echolocation is so quiet it is nearly undetectable to standard equipment, this species represents the most sensitive tier of the site's inhabitants.

For the Brown Long-eared Bat, darkness is not just an absence of light; it is a strictly managed resource. The 2026 management plan treats "Darkness" with the same level of priority as structural integrity. This includes a "Dark Corridor" policy and "Dark Sky" lighting restrictions. Because this species is so vulnerable to light pollution, these measures ensure that the bats can emerge and forage without the "light barriers" that so often fragment urban habitats.

A Strategic Stepping Stone: The Serotine’s Coastal Connection

The Knowle also hosts the Serotine Bat, one of our larger species, which tucks itself into the high, warm eaves of the older stone buildings. From a biogeographical perspective, the Knowle acts as a "gatekeeper" for this species.

Sidmouth sits on the very edge of the Serotine’s primary range. Consequently, the Knowle serves as a strategic "stepping stone," allowing the species to navigate between the coastal cliffs and the inland valleys. If this site were lost, the regional connectivity for the Serotine could effectively collapse, severing a vital link in the ecological network of the West Country.

The Future of Coexistence: The Purpose-Built "Bat House"

As of 2026, the Knowle is in the midst of a high-stakes transition. The redevelopment of the site into a retirement community by McCarthy Stone is a complex feat of ecological engineering. To prevent a regional population collapse, the transition is governed by a strict European Protected Species Mitigation Licence (EPSML).

The centrepiece of this survival strategy is the construction of a dedicated, purpose-built "Bat House." This is not a mere bird-box equivalent; it is a sophisticated structure designed to replicate the thermal conditions of the old council buildings. By carefully managing "emergence points"—the specific gaps where bats exit at dusk—and keeping them in total darkness, the project aims to move the "regionally important" colony from the old offices into their new, permanent home without disrupting their biological cycles.

Conclusion: A New Model for Urban Development

The evolution of the Knowle proves that human progress and wildlife preservation are not a zero-sum game. The transformation from a drab seat of local government to a modern retirement community demonstrates that with rigorous, science-led management, we can preserve the "silent scaffolding" of our natural world.

As we look at the "empty" buildings in our own towns—the redundant offices, the old warehouses, the dusty attics—we must look closer. The Knowle reminds us that these spaces are rarely truly vacant. They are the hidden sanctuaries of the night, and our challenge is to ensure that as we build for our future, we don't leave our most ancient neighbours in the dark. The Knowle proves that our redundant spaces are rarely truly empty; they are the silent scaffolding of the natural world.

Now watch the video: