Condition surveys: Timing is everything 

Plan ahead to survey species within designated timeframes, to avoid BNG plan rejection 

Gaining local planning authority (LPA) approval of your biodiversity net gain (BNG) plan is a huge step toward getting your development project underway.

This approval requires you to consider the conditions of your broad habitat in your site. Habitat condition surveys may depend on the time of year. That means your LPA may not accept a survey as valid if you conduct it outside of the best practice timeframes, as there may be risk of habitats being undervalued or inaccurate.

The danger here is that your development project could suffer costly, potentially months-long delays, if you need to redo the survey.

General timeframes

The optimal general survey season spans from mid to late April through the end of August. This covers the main flowering season, which makes flora and fauna species identification more accurate. For example, it is particularly difficult to survey grassland habitats outside of flowering season.

Habitat surveys

Developers do have leeway on some habitat surveys — assessing an individual tree or urban vegetated and non-vegetated gardens — which can be done at any time. However, sites with hedgerows, forests, or grasslands are best surveyed within the mid-April through late August window. For heathland or wetland related sites, it’s best to wait to assess from June through September.

Protected species surveys

BNG legislation is not a substitute for existing protected wildlife species surveys, and existing requirements remain part of the planning process. It’s common practice to undertake a preliminary appraisal to screen for evidence of a protected wildlife species, which triggers the need for further dedicated surveys.

An initial protected species survey should also include local biological records searches, managed by a local biological record centre, for evidence of protected species in and near to the site. A habitat condition assessment may include the initial appraisal for protected wildlife species to consolidate ecological studies. Should the initial assessment identify evidence of protected species or suitable habitats, an ecologist may recommend additional dedicated species surveys be undertaken, such as bat surveys or badger surveys.

Dedicated protected species surveys are also seasonal, and getting the timing right can be challenging (see species chart). For example, if a grasslands condition survey in August identifies evidence of breeding birds, an additional species study may then be required. However, the developer is in a bit of a difficult spot, as August and the rest of the year is out of the timeframe for surveying breeding birds. In that case, the developer would need to wait until the following April to undertake the breeding birds survey on the site.

Risks and impacts

When surveying outside of recommended timeframes, not only are you risking rejection by your LPA and potentially expensive project delays, but you’re also risking underrepresentation of habitat and/or species. If you categorize a habitat as lower quality, there is a chance that the biodiversity reporting will not be accurate and that you’ll have a negative impact on biodiversity.

Consolidate reporting and start early

Your condition survey can supplement other species data to combine the traditional Preliminary Ecological Appraisal (PEA) with the baseline BNG assessment. This can be the most efficient use of your ecologist’s time — screening for both condition and protected species simultaneously.

Condition assessment is vital as you prepare a BNG planning application for your development site. Ensure you are scheduling the survey in the optimal season and timeframe for the condition assessment and be aware of the potential impact on planning should additional protected surveys be needed.