The reproductive benefits of livestock farming in barn swallowsHirundo rustica: quality of nest site or foraging habitat?

Abstract

Summary1. In many parts of the world, changes in agricultural land-use have led to significant declines of bird species, including aerial insectivores such as barn swallows. In particular, barn swallow populations have been declining across Europe where mixed and livestock farming have been replaced by arable farming. 2. A positive association between livestock farming and barn swallow reproductive success is well documented but the specific roles of micro-and macroenvironment, which are not mutually exclusive, remain unclear. A positive effect of livestock on swallow breeding performance might be due to improved feeding conditions associated with dung around cattle farms (macrohabitat). Barn swallows also might profit from raised and more constant temperatures at the nest site in stables housing farm animals (microhabitat). 3. We analysed data on barn swallows breeding across Switzerland to quantify the effects of livestock farming at the micro-and macrohabitat on the reproductive success of single-and doublebrood pairs. We focus on the effects of nest temperature (expressed as presence of livestock) and food availability around the nest (quantified by the number of manure heaps providing large number of flies). 4. The presence of livestock in the building with the nest and large numbers of manure heaps around nest sites increased nestling survival in double-brood but not in single-brood pairs. Furthermore, the presence of livestock tended to increase the probability of pairs rearing double broods and increased the annual output of double-brood pairs by 0AE8 chicks. Both factors of livestock farming combined increased the annual output by 1AE6 chicks. 5. Synthesis and applications. The productivity of barn swallows depends on the characteristics of the micro-and the macrohabitat. Since changes in farming systems, grazing patterns, landscape heterogeneity and climate may have different effects on micro-and macrohabitats, respectively, they affect productivity of declining bird species in a complex way. Measures designed to enhance habitat quality in aerial insectivores should improve microclimatic conditions at the nest and increase the number of food patches providing airborne insects. In general, habitat improvements should include both spatial scales, namely suitable sites for nesting and accessible food resources on the foraging grounds.

Large-scale spatial distribution of breeding Barn SwallowsHirundo rusticain relation to cattle farming

“…The distribution of breeding Barn Swallows seems to be related to presence of cattle at a farm, but not to the number of heads reared (Møller 2001, Ambrosini, Bolzern, Canova, Arieni et al 2002, Grüebler et al 2010. A reduction in the number of farms with cattle should, therefore, determine a reduction both in the number of colonies and in the mean colony size, even if the number of heads reared at farms that maintain farming remains constant or increases.…”

“…In addition, cowsheds are the favoured nesting sites for the Barn Swallow, and presence of cattle in nesting rooms may mitigate abrupt temperature changes during incubation and nestling rearing (Ambrosini et al 2006, Ambrosini & Saino 2010. Hence, presence of cattle can determine favourable conditions for Barn Swallow reproduction (Grüebler et al 2010).…”

Foraging habitat use of breeding barn swallow (<i>Hirundo rustica</i>) in farmland, estuary, and island

“…Changes in agricultural land-use have been linked to significant declines of barn swallows in many parts of the world [8][9][10][11][12][13][14]. Over the last 70 years, agricultural intensification has divided historically multipurpose agriculture into specialization of livestock or row crop production [15].…”

Wetland, Forest, and Open Paddy Land Are the Key Foraging Habitats for Germain’s Swiftlet (Aerodramus inexpectatus germani) in Southern Thailand

“…These relatively low occupancy rates are probably due to a combination of factors: the failure of the microclimate of buildings to simulate a cave-like environment (Ibrahim, Teo, & Baharun, 2009) and limited suitable foraging habitat due to the deforestation associated with agricultural expansion and urbanization in southern Thailand (Chuangchang & Tongkumchum, 2014;Prabnarong & Thongkao, 2006) and Malaysia (Lim, 2011). Populations of aerial feeders such as swiftlets are likely to be limited by the availability of insects as reported in barn swallow (Møller, 2013) and that land use changes can have significant impacts on insect availability and therefore impact aerial insectivorous birds (Gr8ebler, Korner-Nievergelt, & Hirschheydt, 2010).…”

“…The foraging site usage of glossy and pygmy swiftlets in Philippine are varies by time and microhabitat (Collin, 2000). Nevertheless, foraging patterns of aerial insectivorous birds such as swifts (Chantler & Driessens, 2000), swallows (Brown & Brown, 2001;Gr8ebler et al, 2010;Møller, 2013), and sand martins (Bryant & Westerterp, 1980) are known in Europe and North America. These could be applied to understanding the foraging of Germain's swiftlet.…”