A Rocha Portugal Observatory Report 2009-2010

30 A Rocha Portugal Observatory Report 2009-2010
Transects 1 – 4 (Abicada and Mexilhoeira Grande)
Abicada 1 (Starting point coordinates: 37°09’03.89’’N 8°35’53.58’’W) followed a SSE direction from the
starting point and lay between the central fresh water channel and a small (ruinous) aqueduct through the
lowland of Abicada.
During the survey the grassy vegetation at the beginning of the track was 1 - 2m tall, with an abundance of
herbs (mainly Apiaceae), this then reduced in height to approximately 1m and became more dominated by
grasses from the middle of the transect until its end. Some low bushes (2-5m) were growing in the first half
of the transect. The fresh water channel east of the transect always contained water and was overgrown
with tall reeds for the first 200m; the remainder was clear of reeds. The majority of the vegetation in the
surrounding area was very short and under the influence of freshwater, with channels and temporary
ponds. The habitats here became established after the construction of dykes in the 1950s and 1960s, and
expanded when the former rice cultivation was abandoned. Simonson (1993 and 2005) provides more
information about the history and vegetation of the Abicada area.
Abicada 2 (37°09’07.10’’N 8°35’47.79’’W) followed the unpaved road from the farm ruins northwards until
the first crossroads. Trees (mainly conifers) and shrubs grew along one side of the road – first on the east
side, later on the west side. The other side of the road was grassy with a varying abundance of herbs. The
surrounding area was abandoned farmland and comprised dry grassland with scattered bushes and trees.
The irrigation channel along the left hand side of the road rarely contained water, but supported flowering
plants when water was present, including Mentha sp.
Abicada 3 (37°09’16.72’’N 8°35’50.26’’W) followed the track that leads through abandoned farmland to the
dam on the Alvor estuary. The habitat was open grassland with scattered trees and shrubs. This was the
most “open” transect of the four. There was a nearby irrigation channel that contained water on an
irregular basis, allowing some nectar plants to flower during the dry season.
Mexilhoeira Grande 4 (37°09’33.88’’N 8°35’38.01’’W) was situated on the north side of the N125, on a
south facing hillside. The transect passed through an abandoned orchard with a row of bushes and trees
bordering an allotment. It followed the track leading around this allotment, no more than 10m from the
field boundary. The vegetation was grassy with an abundance of summer-flowering herbs (including
Mentha sp.) particularly at the start.
Results
A total of 604 butterflies representing 22 different species were recorded in this study and summarised
below in Table 1 and Figure 1a. Appendix 2 provides a full record of the species numbers noted in the
weekly transects. Nearly fifty percent of individuals recorded were Pyronia cecilia (Southern Gatekeeper).
Other numerous species included Thymelicus acteon (Lulworth Skipper), Pararge aegeria (Speckled Wood)
and Aricia cramera (Southern Brown Argus). Figure 1b provides an overview of the number of individuals
recorded for each species, excluding records of P. cecilia.