A Rocha Portugal Observatory Report 2009-2010

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28 A Rocha Portugal Observatory Report 2009-2010 explains why the number of apparently held territories does not vary greatly. Additional surveys will show whether 2010 was a particularly unusual year, or whether the decline in AHTs continues beyond 2010. The results may suggest that in 2005 adults were overall more successful at breeding and producing juveniles. If this is the case, in years with many adults a large proportion do not contribute to the number of juveniles. Potentially these adults breed in less suitable habitat or locations prone to disturbance or predation and therefore have very little effect on the number of successfully fledged juveniles. Again, further surveys will help show any patterns, and particular experiments designed to look at geographical variation in breeding success and density will show if these suggestions are accurate. References Burfield I, van Bommel F & Gallo-Orsi, U (2004) Birds in Europe: population estimates, trends and conservation status. BirdLife International, Cambridge. Cramp, S. & Simmons, K. E. L. 1983. (Eds.) The Birds of the Western Palearctic. Vol. III. Oxford University Press. Oxford. Hayden, J. & Heleno, R. (2004) An Informal Guide to the Kentish Plover Annual Survey on the Ria de Alvor Natura 2000 site. A Rocha Portugal Internal Report. Associação A Rocha, Portimão, Portugal. Hayden, J. & Heleno, R. (2005) Monitoring breeding numbers and success of Kentish Plovers Charadrius alexandrinus on the Alvor Estuary. In Simonson, W (ed.) A Rocha Observatory Report for 2004. Associação A Rocha, Portimão, Portugal. Lorenzo, J.A. & Emmerson, K.W. (1995) Recent information on the distribution and status of the breeding population of Kentish Plover Charadrius alexandrinus in the Canary Islands. Wader Study Group Bulletin, 76, 43-46. Mendes, L., Dias, M. & Rufino, R. 2008. Assessment of the importance of non-estuarine coastal habitats for wintering waders in Portugal –January/February 2000. pp. 59–63. In: N.H.K. Burton, M.M. Rehfisch,D.A. Stroud & C.J. Spray (eds). The European Non-Estuarine Coastal Waterbird Survey. International Wader Studies 18. International Wader Study Group, Thetford, UK. Norte, A. & Ramos, J. (2004) Nest-site selection and breeding biology of Kentish Plover Charadrius alexandrinus in sandy beaches of the Portuguese west coast. Ardeola, 51, 255-268. Rufino, R., Araujo, A., Pina, J.P. & Miranda, P.S. (1984) The use of Salinas by Waders in the Algarve, South Portugal. Wader Study Group Bulletin, 42, 41-42.
Introduction A Rocha Portugal Observatory Report 2009-2010 29 BUTTERFLY MONITORING AROUND THE ALVOR ESTUARY, JUNE – OCTOBER 2009 Bert Van der Auwermeulen This project is a follow-up to the 2004 butterfly monitoring project on Quinta da Rocha by the Alvor estuary (Hayden & Carpenter, 2005), which compared results with a study undertaken in 1991 (Gardiner, 1992). Due to a change of landownership, none of the transects used in the previous studies were still accessible, therefore it was necessary to create a series of new transects. Three transects were created near the Roman ruins in Abicada and one on the north side of the N125 in Mexilhoeira Grande. Casual observations in Quinta da Rocha during the weekly bird surveys in 2009, and an additional survey conducted in the Cruzinha garden (Van der Auwermeulen, unpublished), provided more information regarding the presence or absence of species in the locality throughout the year. Aims and objectives The aim of this study was to acquire an understanding of butterfly abundance and species diversity across a variety of habitats around the Alvor Estuary during the summer of 2009, and to make a comparison with previous surveys undertaken in Quinta da Rocha. Methods The methods followed in this study were based on those described in the Butterfly Monitoring Scheme (Pollard & Yates, 1993) that was used for the studies in 1991 and 2004. Using transect lines passing through different habitat types in a given area, provides a representative index of butterfly species diversity and abundance. Whilst walking a set transect, records were made of each butterfly seen in the defined area: three metres either side of the transect line, and five metres in front of the recorder. This did not lead to an estimate of population size, but allowed a comparison to be made with previous studies. The transects were chosen in order to sample a variety of habitats found in Abicada and Mexilhoeira Grande around the Alvor estuary. An obvious location-marker was used (and photographed) as the starting point for each transect to help future relocation. The surveys took place between 09:00 and 13.30 hrs in sunny conditions or, if cloudy, when the temperature exceeded 20 °C. Four transects, each 300m in length, were walked once a week from the beginning of June until the end of August, and once in both September and October. On 2 nd June records were limited to transects 1, 2 and 3. The time taken to walk each transect was longer than in the previous studies and the vegetation was disturbed in order to flush resting individuals. The time to complete one transect was often 30 minutes, especially at the beginning when there were more identification difficulties. Some transects were necessarily crossed again on the way back. In such cases counts were also made of any species which were not recorded the first time. A location map is presented in Appendix 1 and brief habitat descriptions of each transect follows.
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