A Rocha Portugal Observatory Report 2009-2010

More documents

Recommendations

Info

36 A Rocha Portugal Observatory Report 2009-2010 Brown) was ending its flight period at the beginning of the survey period, thus one would expect the numbers of this species to be low, however it might also have been more common in previous years. Some of the Pieridae had also just ended their expected flight period (Euchloe belemia, Euchloe crameri) as well as Medanargia ines (Spanish Marbled White) and Euphydryas aurinia (Marsh Fritillary). The low number of Pieris brassicae (Large White) recorded was assumed to be caused by the scarcity of available food plants. This species clearly takes advantage of Cruciferae growing abundantly in cultivated fields on Quinta da Rocha, a rare situation in Abicada due to the current lack of agricultural activity. In addition, the conditions in 1991 might have been unusually favourable for Pieris brassicae. Regarding the absence of Lasiommata megera (Wall Brown) in 2009, it should be noted that it never appeared in very high numbers and it used to be most numerous on the limestone scrubland and coastal scrubland (transect 3, 5 in 1991), these habitat associations were not represented in the current survey and are no longer accessible on Quinta da Rocha. During the period of this survey the lowlands of Abicada were rather poor both in flowering plants and host plants. The most common butterfly species along Transect A1 was Pararge aegeria (Speckled Wood) which appeared to be taking advantage of the shade provided by the high reeds. Pyronia cecilia (Southern Gatekeeper) was present, but in low numbers. The rest of the butterflies recorded along this transect (Pieris rapae, Pieris brassicae and Papilio machaon), were mainly fast flying, attempting to reach a more sheltered area in the usually windy conditions. The observation of Celastrina argiolus (Holly Blue) was interesting because although widespread and common, this species is most commonly seen in woodland margins rather than in open marshland habitats. However, the individuals observed were seen crossing the open areas and seeking shelter around the reedbed, perhaps indicating that this species is more mobile than many other Lycaenidae. Although the butterfly species diversity in transects A2, A3 and M1 were dominated by grassland species, they clearly differed from each other in terms of composition. Transect A2 was the most sheltered site and included the greatest number of wood/scrubland specialists 4 . In comparison the vegetation around transects A3 and M1 was more open and, as might be expected, a higher number of grassland specialists 5 was recorded at these locations. Muschampia proto (Sage Skipper) and Carcharodus tripolina (False Mallow Skipper), species observed mostly at the Mexilhoeira Grande site, M1, are known to show a strong correlation with their food plants. Conclusions and recommendations The diversity of butterfly species in the wider Alvor Estuary area was similar to that observed in previous studies in Quinta da Rocha. One notable difference in 2009 was the great abundance of Pyronia cecilia (Southern Gatekeeper), representing 48.5% of the total number of recorded individuals. A potential explanation for this difference includes the fact that the Abicada peninsula had less habitat diversity than Quinta da Rocha and the predominant habitat type (grassland) is very favourable for this species. While recognising the fact that populations fluctuate every year, the infrequent occurrence of Pieris brassicae (Large White) and Pontia daplidice (Bath White) was notable. Again the difference in habitat type, in this case the lack of cultivated fields on the Abicada peninsula, may have been a major contributing factor. These two species are not currently endangered but it would be interesting to continue to monitor their population dynamics. 4 Iphiclides podalirius, Satyrium spini, Celastrina argiolus, Pararge aegeria 5 Lycaena phlaeas, Aricia cramera, Polyommatus icarus, Maniola jurtina, Pyronia cecilia, Coenonympha pamphilus, Muschampia proto, Carcharodus tripolina, Thymelicus acteon
A Rocha Portugal Observatory Report 2009-2010 37 The status of Lasiommata megera (Wall Brown) and Thymelicus lineola (Essex Skipper) in this region are unable to be determined by this survey, but potentially indicated a downward trend reflecting the trend on a European level (Van Swaay et. al., 2010). Hayden & Carpenter (2005) stated that this decline could be caused by a change of land use; this would warrant further investigation. Several butterflies present in the Alvor estuary area would benefit from a conservation programme since they have a limited distribution in Portugal or Europe, or because the known populations in Europe are in serious decline. Species of conservation concern in this region include those listed in Table 5. Table 5 Species of conservation concern in the region. Scientific name English name Red list status Notes Gonepteryx cleopatra Cleopatra Uncommon (PT 6 ) Thymelicus lineola Essex Skipper Uncommon (PT) Thymelicus acteon Lulworth Skipper Uncommon (PT) Near threatened (EU 7 ) Decline (EBI) 8 Euphydryas aurinia Marsh Fritillary Habitat directive – Annex II Uncertain (EBI) Lasiommata megera Wall Brown Decline (EBI) Lycaena phlaeas Small Copper Decline (EBI) Coenonympha pamphilus Small Heath Decline (EBI) Spialia sertorius Red-underwing Skipper Uncertain (EBI) EU: Declining rapidly in parts of its range and in urgent need for conservation action Annex II: Species that require the designation of special areas of conservation (LIFE) It would be useful to direct future butterfly monitoring programmes towards identifying existing populations of the above species in the Alvor estuary area and developing practical conservation action plans. Two suggested projects: The Lulworth skipper should become the main priority for a future butterfly study. At present it is still common and widespread in the area, without showing signs of a decline. The implementation of a comprehensive conservation strategy may prevent this population from following the current decline in the great majority of Europe. The Marsh fritillary is known to be very vulnerable to habitat loss and is therefore listed on Annex II of the Habitat directive. It occurs commonly (although localised) in the Alvor estuary and it is strongly correlated to its food plants Lonicera implexa and Scabiosa atropurpurea. The imagos, caterpillars and food plants are all easy to recognise, making it an ideal species for a monitoring scheme carried out by volunteers. For both species, possible threats and suggestions for conservation measures are described in the Red data book of European butterflies (Van Swaay & Warren, 1999).Recommended future studies could include further investigations into invertebrate associations (particularly lepidoptera) with habitat types occurring in the Alvor estuary area. There is benefit in sharing butterfly records with national (Tagis) and European species recording schemes in order to assist monitoring efforts. A locally developed database for the recording of butterfly observations would aid this suggestion. 6 PT: Red list status of Portugal based on As Borboletas de Portugal (Marvalhas, 2003) 7 EU: Red list status of Europe based on European Red list of butterflies (Van Swaay, Cuttelod, et.al., 2010) 8 EBI: The European Butterfly Indicator for Grassland species 1990-2009 (Van Swaay et.al., 2010)
Page 1 and 2: A ROCHA PORTUGAL OBSERVATORY REPORT
Page 3: Contents Preface The Great Spotted
Page 8 and 9: 6 A Rocha Portugal Observatory Repo
Page 10 and 11: 8 A Rocha Portugal Observatory Repo
Page 12 and 13: 10 A Rocha Portugal Observatory Rep
Page 42 and 43: Appendix 2. Weekly transect data fr
Page 44 and 45: 12-08-2009 19-08-2009 25-08-2009 22
Page 88 and 89:
86 A Rocha Portugal Observatory Rep
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
show all

A Rocha Portugal Observatory Report 2009-2010

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?