The exposure and toxicity of pesticides to amphibians

Amphibians and pesticides
were not tracked during migratory phase). Some were found to forage in arable fields at night up to
20m from the scrub they took refuge in during daylight. This suggests that total distance moved across
the fields could be 40m or more.
Using night counts of migrating toads over two years (Hartel and Demeter 2005), breeding migration
was found to last 19 to 36 days from mid March. In the study area the pasture land formed a corridor
between the forest and the pond such that very few migrating toads were found on arable land. The
furthest recorded toad was 450m from the pond near the forest area. No active toads were found when
temperature was below 5°C. In periods of intense activity toad density within 10m from the pond was
0.16 toads/m 2 while at 150m distance this was 0.055 toads/m 2 .
In a study of migration distances in March to April, maximum recorded movements in agricultural
areas ranged from 450 to 518m. Maximal distances moved in other habitats ranged from 170-1835m
(Kovar et al 2009).
In a study of movements towards the breeding pond (Sinsch et al. 1988a), toads were observed at 70-
240m from the breeding pond and did not move directly towards the spawning site but entered the
pond from any shore. Some paths deviated and allowed the pond to be approached via a ditch which
terminated at the pond. Post spawning migration was also monitored with individuals recorded up to
1.6km from the pond. In May and June migratory behaviour decreased with animals staying in their
‘home range’ until autumn migration or hibernation. Of 29 toads observed, 23 hibernated at distances
of 70-420m from the breeding pond while six hibernated in their summer home range 1060-1230m
from the pond.
Berger et al (2011b) monitored movements of common toads on arable land using radio-telemetry
during post breeding movements in August and September. Two types of behaviour were found
depending on the amount of cover present on the field. Where fields were freshly ploughed, animals
moved across these quickly, one animal moving 580m in one night. In stubble fields with volunteer
cereals or rape only or set-aside, small daily movements were observed, often less than 10m. In one
case an animal using such a field survived the field being ploughed and moved to adjacent set-aside
land. Where animals remained on arable land, cover was found under plant material, in small mammal
burrows or cracks under clods of earth. These resting places were often within 35m of non-arable
areas. Toads tracked using the fluorescent dye method behaved in a similar fashion quickly traversing
freshly ploughed fields and winter rape to reach areas with dense vegetation.
1.3.1.2. Movement information for Bombina bombina
In a study of migration distances in March to April, maximum recorded movement in an agricultural
area was 167m. Maximal distances moved in other habitats ranged from 160-230m (Kovar et al 2009).
1.3.1.3. Movement information for Bufo calamita/Epidalea calamita
Radio-tagged individuals were tracked in barley fields on the way to (end of January to mid- April)
and from (early April to September) breeding ponds (Miaud et al 2000). Maximum daily distances
moved ranged from 22m to 577m in spring, and 125m to 353m after breeding. Maximum distances
moved by a toad in each period were 934m and 4411m respectively. Marginal habitats such as ditches
with vegetation and stone embankments were used as shelter sites.
Home range in an area of cereal agriculture was determined in a study by Miaud and Sanuy (2005).
Median home range area was 0.5 ha (range 0.1-11 ha) during the breeding season (January-April).
Home range size increased during the post-breeding season (April-September) with a median
minimum concave polygon of 4.1 ha. Home ranges included crop fields but these were less preferred
compared to other habitats. Order of habitat preference was stone embankments/ditches with reeds >
Supporting publications 2012:EN-343 19
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