Falling short: inconsistent statutory compliance and widespread best-practice neglect in commercial reptile survey reports across Great Britain

Abstract Commercial reptile surveys produced by ecological consultants inform mitigation decisions in regard to development across Great Britain, yet the quality and rigour of these surveys have rarely been assessed. This study evaluated 38 commercial reptile survey reports (2009 to 2024) on three protected native reptile species: common lizard ( Zootoca vivipara ), slow worm ( Anguis fragilis ), and grass snake (N atrix Helvetica ), using a novel nine-category scoring rubric, created from both statutory guidance and wider best practice literature. Reports scored significantly higher on categories adopted from statutory guidance in comparison to non-statutory categories (Wilcoxon signed-rank, p < 0.001), with population estimates and recommended monitoring most consistently neglected. The total rubric score significantly improved from 2009 to 2024 (Spearman's ρ = 0.378, p = 0.019) and was positively associated with reported development impact ( ρ = 0.459, p = 0.004), though unrelated to recommended mitigation strategies ( ρ = -0.041, p = 0.807). Reports concluding reptile absence scored significantly lower than presence reports on survey month and the number of presence/absence surveys undertaken ( p = 0.002 and p = 0.022 respectively); the categories guidance ties most closely to reliably ruling out presence, suggesting some absence conclusions may rest on insufficient survey effort. These findings indicate that current statutory guidance alone is insufficient to guarantee robust and reliable reptile survey outcomes. Revising guidance to incorporate non-statutory best practice, and considering alternative, centrally delivered compensation models already demonstrating success for other protected species, may be necessary to improve outcomes for reptile conservation in Great Britain.