Raptor breeding sites as a surrogate for conserving high avian taxonomic richness and functional diversity in urban ecosystems

Raptor research during the COVID-19 pandemic provides invaluable opportunities for conservation biology

“…Although there is a clear pattern of raptors being associated with areas of high biodiversity, this relationship may not generalize across all ecosystems ( Estrada and Rodríguez-Estrella, 2016 ), and more research is needed. For example, in urbanized Kanagawa, Japan, breeding northern goshawks serve well as indicators of bird species richness and functional diversity ( Natsukawa, 2020 ), but this does not hold true for non-urban areas elsewhere in Japan ( Ozaki et al, 2006 ). It is therefore possible that the utility of the goshawk as an indicator species is mediated by anthropogenic factors that are only present within cities ( Natsukawa, 2020 ).…”

“…For example, in urbanized Kanagawa, Japan, breeding northern goshawks serve well as indicators of bird species richness and functional diversity ( Natsukawa, 2020 ), but this does not hold true for non-urban areas elsewhere in Japan ( Ozaki et al, 2006 ). It is therefore possible that the utility of the goshawk as an indicator species is mediated by anthropogenic factors that are only present within cities ( Natsukawa, 2020 ). The COVID-19 anthropause presents an opportunity to study correlations between raptors and biodiversity during a period of significantly reduced human activity, although it is possible that lockdowns were too short in duration to cause measurable perturbation.…”

Raptor breeding sites indicate high plant biodiversity in urban ecosystems

“…To date, only two studies have evaluated the usefulness of raptors as conservation surrogates for biodiversity in urban ecosystems. In one study, biodiversity was estimated by the richness of breeding birds 18 , employed as “background taxa” (the taxonomic group expected to benefit from the conservation of the surrogate species, following 10 ), whereas the other study focused on wintering birds as background taxa 19 . In these assessments, there was a direct predator–prey relationship between the biodiversity surrogate (a bird-eating predator) and the background taxa (breeding or wintering birds).…”

Top predators as biodiversity indicators: A meta‐analysis

“…For example, the northern goshawk (Accipiter gentilis; hereafter goshawk) is a raptor typical of mature forest that often preys preferentially on birds and can be associated with high avian and tree diversity (e.g. Burgas et al, 2014;Natsukawa, 2020Natsukawa, , 2021Natsukawa et al, 2021;Sergio et al, 2005). Whilst there is supporting evidence on the capacity of this species to impose causative changes in avian diversity (Burgas et al, 2021), it is difficult to hypothesise a causative link with tree diversity, more likely ascribed to habitat selection strategies.…”

“…For many predators, their bio-indicator role is likely to be generated by a mix of causative and non-causative factors. In this example, the northern goshawk (Accipiter gentilis; goshawk) has been repeatedly shown to signpost high biodiversity value of its supporting forest ecosystem (Burgas et al, 2014;Natsukawa, 2020Natsukawa, , 2021Natsukawa et al, 2021;Sergio et al, 2005), as here portrayed by interspersion of closed forest and glades, mix of coniferous and deciduous tree species, co-occurrence of multiple understory and regeneration layers, presence of dead wood covered by moss on the forest floor, all of which provide diversified niches for multiple taxa (e.g. large anthill in the background).…”