Abstract
Lepidoptera are one of the most threatened invertebrate taxa undergoing global declines in diversity and abundance. Fragmentation and deterioration of habitats through changes in land management practices and climate change threaten the persistence of populations within landscapes. Specialist species restricted to specific habitat and climatic conditions are more at risk as changes are also evidenced at the micro scale.This study focuses on micro-habitat and micro-climate selection in the specialist, Endangered and declining High Brown Fritillary (Fabriciana adippe), and the more generalist Dark Green Fritillary (Speyeria aglaja). It is the first to compare the requirements of these two closely related species in their overlapping range across the whole lifecycle. It builds on previous research undertaken in the 1990s and reassesses requirements under current environmental conditions. Micro-habitat and micro-climate selection are assessed through field observations of oviposition behaviour. Both species display specificity in micro-habitat and micro-climate, but this is greater in the High Brown Fritillary and present at several life stages. It occupies a narrower micro-habitat niche and has a lower tolerance to micro-climatic cooling than the Dark Green Fritillary. This work confirms that the High Brown Fritillary females select sites that accommodate the thermal requirements of the larvae.
This study is also the first to provide a controlled study on the impact of widely used management techniques for the restoration of neglected Bracken stands for these species. A single application of the treatments had no long-term effect on the habitats, and thus management should be applied annually until the target habitat is achieved before changing to a maintenance regime. Habitat management for the High Brown Fritillary and similarly specialised butterflies should be carried out at the patch scale to create optimum breeding conditions, but also in the context of the wider landscape, creating a network of connected sites.
Date of Award | 18 Mar 2024 |
---|---|
Original language | English |
Awarding Institution |
|
Supervisor | PAUL ASHTON (Director of Studies), ANNE OXBROUGH (Supervisor) & Rosa Menendez-Martinez (Supervisor) |
Keywords
- Lepidoptera
- Fabriciana adippe
- Speyeria aglaja
- oviposition preference
- Micro-habitat
- Micro-climate
- niche separation
- overwinter
- Bracken
- habitat management
- Pteriduim aquilinum