Do Corncrakes Crex crex benefit from unmown refuge strips?

Abstract

SummaryCorncrakes Crex crex mainly breed in grassland, where they are threatened by mowing. Conservation requires delayed mowing or modified mowing methods. In large fields, it has been suggested that leaving strips of uncut grass may reduce mortality, especially of unfledged chicks. We attended mowing operations (2012–2015) in the Lower Oder Valley National Park in north-eastern Germany, where 10-m refuge strips were introduced. We documented the escape behaviour of adults and chicks and their use of refuge strips by observations and radio-telemetry. Flightless chicks crossed significantly shorter distances of mown area (< 20 m) than adults. When mowing from the outside inwards, chicks were not able to successfully escape to the field edge at > 31 m, adults at > 60 m distance to the edge and returned to the unmown block. Twenty-three percent of adults, 30% of families and 49% of independent chicks survived in 10 m-wide strips until such strips were either mown or left as refuges. Whereas adults departed the strips the next day, independent chicks stayed for up to 22 days after mowing in 15–30 m wide refuges. We recommend refuge strips for breeding sites where more effective measures cannot be applied. Farmers face less additional effort and lower financial losses compared with delayed mowing. A width of 10 m should be considered as the absolute minimum, because most birds left the cover already > 10 m for the first time and only wider refuges served as temporary habitat for young.

The effects of farming intensification on an iconic grassland bird species, or why mountain refuges no longer work for farmland biodiversity

“…This measure included delayed mowing (no mowing between 25 May and 15 July within the elevational belt considered by our study), with positive outcomes for corncrakes and likely other grassland species. This is fully coherent with the positive effects found elsewhere for management (whether based on AESs or not) promoting postponed or alternated mowing, or the preservation of unmanaged strips of adequate width (Arbeiter et al, 2018(Arbeiter et al, , 2017bBerg and Gustafson, 2007;O'Brien et al, 2006), as well as with the positive effect on the short-term of grassland abandonment, which result in suitable (but transitory) unmanaged grassland (Keiss, 2003). Such measures could also promote the availability of invertebrate preys for corncrakes (Arbeiter et al, 2020) and of suitable conditions for other bird species (Broyer et al, 2020).…”

Preserving an obscure bird: achievements and future challenges of Corncrake (Crex crex Linnaeus, 1758) conservation in Hungary

“…A recent study in Germany added further details to this measure by the radio tracking of adult and juvenile Corncrakes (Arbeiter et al 2015). The results of this study suggested that refuge stripes should be at least 10 m wide, since the majority of Corncrakes (25-66%) stayed in the unmown area until its width went below this threshold.…”

“…Among the currently applied measures, inside-outward mowing, refuge stripes and delayed mowing until 1-15 August are well established by previous studies (see Koffijberg & Schäffer 2006, BirdLife International Corncrake Conservation Team 2016. Thanks to a recent study, we also learned that refuge stripes should be at least 10-30 metres wide to provide suitable cover and habitat for young Corncrakes until fledging (Arbeiter et al 2015). It would be also important to involve more farmers in agri-environment programmes at least in the most important breeding areas, and thereby increase the proportion of breeding pairs affected by conservation measures.…”

The Impact of Unmown Refuge-Strips on the Breeding Site Fidelity of Common Quail (Coturnix Coturnix) – A Case Study

“…The five birds detected only during the second survey after mowing might have arrived from completely harvested or mown neighbouring areas. Several studies emphasized the positive effects of unmown refuge areas on the survival of farmland birds (VICKERY et al 2001;BROYER 2003;ARBEITER et al 2017). In the MOSON Project, apart from the Common Quails, bird species that benefit from the uncut grass strips include the vulnerable Great Bustard (Otis tarda), the Grey Partridge (Perdix perdix), the Pheasant (Phasianus colchicus) as well as passerines like the Skylark (Alauda arvensis), the Yellow Wagtail (Motacilla flava), the Whinchat (Saxicola rubetra) and the Corn Bunting (Emberiza calandra).…”