British Birds June 2020

Published on 01 June 2020 in Latest issues

Highlights from a long-term study of Tengmalm’s Owls: cyclic fluctuations in vole abundance govern mating systems, population dynamics and demography  Results from a 47-year study of Tengmalm’s Owls in western Finland show that abundance of their main prey (Microtus and Myodes voles), and the three-year, high-amplitude fluctuations in vole populations, is fundamentally important in regulating the owl populations.

Plumage development and identification of the Spanish Imperial Eagle  The field separation of the Spanish Imperial Eagle from the formerly conspecific Eastern Imperial Eagle is reviewed. The recent population increase and range expansion of the former has enabled a much-improved understanding of its plumages and moult. Both species may potentially be encountered as vagrants in western Europe.

A significant decline of breeding Peregrine Falcons in coastal north and west Cornwall, 2015–19  The breeding population of Peregrine Falcons on the Atlantic coasts of north and west Cornwall appears to be declining dramatically. It is suggested that the primary cause of the population decline is an increase in adult mortality or emigration. Early indications from 2020 are that the observed decline is continuing.

BB eye  Agricultural policy – what does it mean for our farmland birds?

Rarities Committee news  New species – New guidance for Subalpine Warblers – Guidance for sound recording – Call for new members

Letters  Do taxonomic changes affect conservation? The species status of the Red Grouse

My patch  Morden Hall Park 

News & comment and Recent reports complete the June issue.

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