Long‐term trends in wind speed, insect abundance and ecology of an insectivorous bird

Abstract

Citation: Møller, A. P. 2013. Long-term trends in wind speed, insect abundance and ecology of an insectivorous bird.Ecosphere 4(1):6. http://dx.doi.org/10.1890/ES12-00310.1Abstract. Recent climate change has affected spatial and temporal patterns of temperature and precipitation, but also wind speed. Wind affects the abundance and the distribution of flying insects and can therefore influence the abundance of food for insectivores including insectivorous birds. I tested for temporal trends in wind speed, assessed the effect of wind speed on the abundance of flying insects, and tested for effects of wind speed on reproduction and adult survival rate, using long-term data on the barn swallow Hirundo rustica from 1971-2011. Wind speed varied largely independently among the months April-August, with a decreasing trend during 1971-2011 for July only. The abundance of flying insects decreased strongly with increasing wind speed during summer. Decreasing wind speed during July coincided with the pre-laying period of the second brood of the barn swallow, and years with stronger wind in July had lower abundance of food before laying during 1997-2011 and lower breeding success. Adult barn swallows had lower body mass in years with windy summers, and adult annual survival rate to the next year decreased both when wind speed increased and when body mass was reduced. These findings suggest that wind plays an important role in the ecology of insectivorous birds as shown by relationships with reproductive success and survival.

A comparative study of insect abundance and reproductive success of barn swallows Hirundo rustica in two urban habitats

“…The observed increasing insect densities with progression of the season are consistent with earlier studies on barn swallows (Bryant and Turner ), showing that the size of boluses supplied to barn swallow nestlings increased significantly during the breeding season. The significant decline in insect density with the increasing wind speed during the breeding season was in accordance with increasing wind speeds which affect insect abundance negatively (Møller ).…”

“…Similarly, Leffelaar and Robertson () reported a strong correlation between the brood mass and the feeding rates in tree swallows. Møller () demonstrated that increasing wind speeds negatively affected insect abundance, which may explain the lower feeding rates per capita in the first broods at higher wind speeds. Likewise, the feeding rates of the first broods decreased with the number of nestlings, as in Saino et al (), who demonstrated that barn swallow nestlings in enlarged broods received less food per capita than nestlings in reduced broods.…”

Patterns of Fluctuating Selection on Morphological and Reproductive Traits in Female Tree Swallow (Tachycineta bicolor)

“…Survival from hatchling to fledgling (more so than hatchling success), for instance, should be directly affected by morphological characters involved in parental capacity to feed nestlings. For example, insectivorous birds with shorter wings often have higher success at capturing preys, resulting in higher fledgling success (Møller et al 2006;Møller 2013;Tarka et al 2014). Therefore, to have a more complete understanding of variation in selection patterns, one should attempt to disentangle the relative effects of several morphological and reproductive traits on different fitness components during successive episodes of selection.…”

Quantifying rapidly declining abundance of insects in Europe using a paired experimental design

“…I used the following procedures for quantifying the abundance of insects. I counted the number of dead insects on the windscreen of a car driven at a fixed speed of 80 km, while recording the area of the windscreen, weather, and the brand of car (Møller, ). This was done at the same road for 41 25 km transects in 1997 and again for 41 transects in May–August 2017 at Pandrup, Denmark.…”

“…These 18 study plots were combined with seven published data sets (reported in Conrad et al, 2006;Conrad et al, 2002;Hallmann et al, 2017;Hofmann, Fleischmann, & Renner, 2018;Møller, 2019;Schuch, Bock, Krause, Wesche, & Schaefer, 2012;Shortall et al, 2009) that were similarly investigated twice by the same scientists during an early study in 1970-1975 and again in 2015-2018. I used the following procedures for quantifying the abundance of insects. I counted the number of dead insects on the windscreen of a car driven at a fixed speed of 80 km, while recording the area of the windscreen, weather, and the brand of car (Møller, 2013).…”