Take-home:
🌲 As pine martens expand, spatial refuges for owls shrink.
🦉 Food availability remains the strongest driver of breeding success.
⚖️ Still early in the colonisation so as pine martens increase, we may see evidence of the alternative prey hypothesis to come but not just yet.
➡️ #BOUatEOU

Findings:
🟢 Owl nest failure was strongly controlled by vole abundance.
🟠 Pine marten occupancy also increased failure, but effects were additive, not interactive.
❌ No support for the Alternative Prey Hypothesis — marten effects didn’t increase when voles were low.

Key questions:
❓Does pine marten recolonisation increase owl nest failure?
❓Do voles buffer this risk (via APH)?
❓Is there evidence of spatial or temporal refugia from predation?
We combined long-term nest records with pine marten occupancy data + artificial nest experiments.

My study system:
📍Kielder Forest, UK
⏳ 40 years of tawny owl breeding data
🦊 Return of predators: buzzards, goshawks, foxes, badgers & most recently pine martens
🌱 Voles = critical food resource for tawny owls, but also eaten by pine martens

Ecosystems are often unstable, but they can be stabilised by refugia — safe spaces in time or space where species can avoid predation.
I also test the Alternative Prey Hypothesis (APH): when a preferred prey declines, predators switch to alternative prey.
👉 Could this explain owl breeding failure?