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High traffic-related mortality and few nests indicate limited value of public road verges for bumblebee populations

Blomqvist, Sofia LU ; Smith, Henrik G. LU orcid ; Olsson, Peter LU orcid ; Klatt, Björn K. LU orcid and Herbertsson, Lina LU orcid (2026) In Biological Conservation 319.
Abstract

Road verges resemble natural bumblebee habitats in terms of flowers and nesting substrates. Hence, they may benefit bumblebee populations, especially in landscape where other floral and nesting resources are scarce. Such benefits may, however, be offset by the adjacency to traffic. As bumblebees move between habitat patches, effects on populations may manifest across landscapes rather than in the local road verge. Using a split-plot design, we studied how wild bumblebees respond to traffic intensity at local and landscape (within 1000 m) scales. We did this along a gradient of open, uncultivated land, including traditionally managed grasslands, which is an important habitat for bumblebees. In 20 study landscapes, we monitored bumblebees... (More)

Road verges resemble natural bumblebee habitats in terms of flowers and nesting substrates. Hence, they may benefit bumblebee populations, especially in landscape where other floral and nesting resources are scarce. Such benefits may, however, be offset by the adjacency to traffic. As bumblebees move between habitat patches, effects on populations may manifest across landscapes rather than in the local road verge. Using a split-plot design, we studied how wild bumblebees respond to traffic intensity at local and landscape (within 1000 m) scales. We did this along a gradient of open, uncultivated land, including traditionally managed grasslands, which is an important habitat for bumblebees. In 20 study landscapes, we monitored bumblebees along each of three roads, one private road with negligible traffic and two public roads with contrasting traffic intensity (high and low). We assessed mortality, within-season variation in abundance (early queens, early and late workers, and new reproductives), and nest density (supported by scent-trained dogs). Densities of living early queens and workers increased with flower cover in the road verge but decreased with local traffic intensity, which was paralleled by increasing numbers of dead queens and workers. Nests were rare in road verges along the public roads compared to along the private road verges, where traffic was negligible. Despite that traffic clearly increased mortality and restricted the benefit of flowers in road verges, we observed no negative effect of traffic at the landscape-scale. This suggests that other factors are regulating bumblebee populations. We conclude that traffic limits the benefit for bumblebees of flower-enhancement strategies in road verges, but if implemented along roads with low traffic, such actions may be beneficial by promoting forage availability.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bee conservation, Bee mortality, Bombus, Bumble bee, Pollinator, Roadside habitat, Traffic intensity
in
Biological Conservation
volume
319
article number
111872
publisher
Elsevier
external identifiers
  • scopus:105037480051
ISSN
0006-3207
DOI
10.1016/j.biocon.2026.111872
language
English
LU publication?
yes
id
6eee69d6-92cd-4afd-83a7-94efe78a7676
date added to LUP
2026-08-13 16:04:43
date last changed
2026-08-13 16:05:32
@article{6eee69d6-92cd-4afd-83a7-94efe78a7676,
  abstract     = {{<p>Road verges resemble natural bumblebee habitats in terms of flowers and nesting substrates. Hence, they may benefit bumblebee populations, especially in landscape where other floral and nesting resources are scarce. Such benefits may, however, be offset by the adjacency to traffic. As bumblebees move between habitat patches, effects on populations may manifest across landscapes rather than in the local road verge. Using a split-plot design, we studied how wild bumblebees respond to traffic intensity at local and landscape (within 1000 m) scales. We did this along a gradient of open, uncultivated land, including traditionally managed grasslands, which is an important habitat for bumblebees. In 20 study landscapes, we monitored bumblebees along each of three roads, one private road with negligible traffic and two public roads with contrasting traffic intensity (high and low). We assessed mortality, within-season variation in abundance (early queens, early and late workers, and new reproductives), and nest density (supported by scent-trained dogs). Densities of living early queens and workers increased with flower cover in the road verge but decreased with local traffic intensity, which was paralleled by increasing numbers of dead queens and workers. Nests were rare in road verges along the public roads compared to along the private road verges, where traffic was negligible. Despite that traffic clearly increased mortality and restricted the benefit of flowers in road verges, we observed no negative effect of traffic at the landscape-scale. This suggests that other factors are regulating bumblebee populations. We conclude that traffic limits the benefit for bumblebees of flower-enhancement strategies in road verges, but if implemented along roads with low traffic, such actions may be beneficial by promoting forage availability.</p>}},
  author       = {{Blomqvist, Sofia and Smith, Henrik G. and Olsson, Peter and Klatt, Björn K. and Herbertsson, Lina}},
  issn         = {{0006-3207}},
  keywords     = {{Bee conservation; Bee mortality; Bombus; Bumble bee; Pollinator; Roadside habitat; Traffic intensity}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Biological Conservation}},
  title        = {{High traffic-related mortality and few nests indicate limited value of public road verges for bumblebee populations}},
  url          = {{http://dx.doi.org/10.1016/j.biocon.2026.111872}},
  doi          = {{10.1016/j.biocon.2026.111872}},
  volume       = {{319}},
  year         = {{2026}},
}