Mismatches between breeding success and habitat preferences in Hen Harriers Circus cyaneus breeding in forested landscapes

Abstract

During the past century, the upland breeding areas of Hen Harriers in Ireland have been extensively afforested. There is no evidence that this species avoids breeding in heavily forested landscapes and, indeed, young commercial forests in their second rotation are often selected as nest‐sites. However, Hen Harriers have coexisted with these forested areas for only a few decades and it is possible that such landscapes are suboptimal. We examined the relationship between breeding success and habitat using a dataset spanning three years and four study areas in the south and west of Ireland. We assessed whether nest success and fledged brood size were related to habitat type, both at the nest‐site and in the surrounding landscape. Neither measure of breeding productivity was related to total forest cover or to percentage cover of closed canopy forest in the landscape. However, in a subset of areas, high cover of second‐rotation pre‐thicket (young forests planted on land from which a first rotation has already been harvested) in the surrounding landscape was associated with low levels of breeding success. This may be due to factors related to predation, disturbance or prey availability. The fact that second‐rotation pre‐thicket is a preferred habitat for nesting in Ireland suggests that Hen Harriers may be making suboptimal decisions in the landscapes available to them.

The status of the Hen Harrier,Circus cyaneus, in the UK and Isle of Man in 2010

“…Further research into the differences in forest composition and patterns of restructuring between Northern Ireland and Scotland would help to shed light on these opposing trends. The dynamic nature of forestry means that assessing the future potential of forests across the UK for nesting Hen Harriers is complex and will need continued monitoring (Fielding et al 2011, Wilson et al 2012.…”

A Resource-Based Modelling Framework to Assess Habitat Suitability for Steppe Birds in Semiarid Mediterranean Agricultural Systems

“…April – September); and (2) different windows of time around bird surveys: (2a) the month when the survey was undertaken (May); (2b) including the month before sampling (Apr-May); (2c) including one month after sampling (May-Jun); and (2d) including one month either side of sampling (Apr-Jun). This was done to evaluate the strength of the relationship between May occurrence data and suitability over different time periods because, although it is known that habitat suitability throughout the complete breeding season is important for species’ fitness, habitat selection patterns may respond to more discrete periods [31] , [32] . For temporal integration of , only months within nesting period were taken into account.…”

The influence of habitat edge on a ground nesting bird species: hen harrier Circus cyaneus

“…The possibility of a mismatch between hen harrier nest site selection and their relationship with some habitats was discussed in previous studies (Wilson et al 2009, Wilson et al 2012a. Wilson et al (2009) discuss hen harrier preference for nesting in second rotation forestry despite higher predation pressure.…”