ure News 11 - Gibraltar Ornithological & Natural History Society

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GIBRALTAR NATURE NEWS 10 Seabird monitoring was carried out at the Europa Point Marine Observatory during the late afternoon and evening hours in the cool breeze of the early summer months. As expected, June was dominated by immature Audouin’s Gulls heading out of the Mediterranean, with the first juvenile birds observed from the 28th July. Passage was below average for the third year running possibly due to unfavourable wind conditions. Mediterranean and Black-headed Gulls were also observed in small numbers during this period with some Oystercatchers, Common Sandpipers and Whimbrels seen on occasions, but overall there were no unusual observations. Common Waxbill EUROPEAN BAT NIGHT IN GIBRALTAR 2008 This year's "European Bat Night" took place at the Open Air Theatre, within the Alameda Botanic Gardens on Saturday 30 August 2008. Just over twenty people attended the event, where they could sit very much as an audience watching a performance. A breezy evening appeared to restrict the activities of the Soprano pipistrelles Pipistrellus pygmaeus which are resident in the area and would usually have been our most frequent visitors. The Gibraltar Ornithological and Natural History Society (GONHS), which organised and promoted the event, had set up a bat detector connected to a loudspeaker, through which participants would be able to hear 'heterodyne' interpretations of the otherwise ultrasonic bat calls. Well after sunset, the first Schreiber's or Large bent wing bat Miniopterus schreibersii began their forays over the area of the pond and stage, often providing a little more than a glimpse before they Monarch Butterflies Danaus plexippus were a common sight in the Alameda Botanic Gardens and around Gibraltar, where they bred successfully, until they were killed off by the cold spell of January 2005. This included the only day in recorded history when frost lay on the ground for several hours in parts of the garden. Since then, the only observations were sporadic sightings of the butterfly from time to time, but inspection of the foodplant in the gardens revealed no signs of the caterpillar. During the autumn and winter of 2007–08, a concerted effort was made to establish additional foodplants for the butterfly. Over 600 Asclepias curassavica plants were grown from seed in the gardens and planted out in key beds close to moist and shady locations where plenty of other nectar-bearing flowers were also grown. The plan after this was to establish a colony by transferring caterpillars from nearby BIRDING SCENE Some early returning passerine migrants were recorded on the Rock in summer, with Hoopoes and a Woodchat Shrike in mid June, and a flock of forty Flamingos over the harbour provided some colour to the month. Other passerine migrants in July included a Great Spotted Cuckoo, picked up exhausted, and a Spotted Flycatcher and a Melodious Warbler on Windmill Hill. July still had a late couple of Black Kites and Honey Buzzards heading north, with the first southbound raptor, a Black Kite on the 3rd. Raptor passage was poor during most of August due to unfavourable winds but the end of the month saw a change in the weather and over 10,492 Honey Buzzards were counted in a five-hour period as winds changed to westerly, together with good numbers of other raptors and many hundreds of Swallows and Beeeaters. A Waxbill seen flying south over the harbour area on the 16th of the month was relocated at the Botanic Gardens five days later and identified as a Common Waxbill. It remained in the Gardens for most of September feeding on grass seeds close to the office buildings. This species has a feral population in southern Spain and Portugal and has been recorded before on the Rock. disappeared from view. The bat detector proved its worth, by allowing all those present to hear its echolocation calls, even if some of the participants failed to spot the bat itself. MONARCH BUTTERFLIES ARE BACK colonies in Spain to the gardens, but this proved unnecessary as natural colonisation took place. In late May and June many plants showed signs of damage and on closer inspection the first caterpillars of the Monarch were found. During the summer months several broods emerged, once again providing the Botanic Gardens with a wonderful spectacle of nature as many of the Monarchs floated down from bloom to bloom to sip the nectar and provide visitors with marvellous views of these insects. The policy of the Alameda Botanic Gardens not to use either herbicides or pesticides is fundamental to the richness of the biodiversity of the gardens, where one can find an interesting selection of insect life living in harmony in a naturally controlled and balanced way that complements the botanical displays and enhances the conservation value of these gardens. The weather broke with early rains during the middle of September, resulting in some falls of migrants that would have gone through unnoticed otherwise. These produced several Redstarts, Willow Warblers, Tawny Pipits, Ortolan Buntings and early falls of Stonechats with the first Crag Martin and Grey Wagtail in mid month. Interesting sightings included Eleonora’s Falcons early in the month, four Night Herons over Jews’ Gate, two Grasshopper Warblers and a Trumpeter Finch, (9th record) on Windmill Hill. Thundery conditions on the 29th saw falls of Yellow Wagtails, Tawny and Tree Pipits, Willow Warblers, Wheatears, Whinchats, Stonechats and six Quails, with many of the migrants observed in the Gibraltar Botanic Gardens seen chasing scarab beetles as they emerged during the rains. The following days continued to bring migrants with a Wryneck, Redstarts, Pied and Spotted Flycatchers and many Phylloscopus Warblers, seen in the gardens and Short-toed Lark, Subalpine and Spectacled Warblers and Corn Bunting adding to the species list. Full details of all bird observations will be published in the 2008 Gibraltar Bird Report. Albert Yome, GONHS coordinator for European Bat Night, was on hand to answer many questions on bats, having first introduced the evening with a short chat on Gibraltar's bats and the threats they face. Albert Yome talking to those present
1ST INTERNATIONAL CAVE MONITORING FIELD WORKSHOP Jointly organised by Royal Holloway, University of London, University of Innsbruk and the Gibraltar Ornithological and Natural History Society. Monitoring headquarters, St Michael’s Cave In February, GONHS will be hosting the worlds first International Cave Monitoring Field Workshop. This will be a four-day event bringing cave and climate science specialists from all over the world to Gibraltar. Climate change studies have been a hot topic now for quite a few years involving different approaches to understand what the climate was like in the past. Gibraltar is in a uniquely important location to carry out this research not only because of its geographical location at the junction between two continents and two oceans but also because of the abundance of caves containing stalagmite records of past climates and long history of weather recording since the 18th century. Scientists involved in climate studies use a range of different specialised fields to uncover the past. For example, botanists can use tree rings to get a climate record over the last few millennia, scientists in polar regions take very long ice core samples spanning tens of thousands of years which provide a record of the atmosphere when the snow and ice were formed. Exactly the same happens when a stalagmite in a cave grows. The “rings” in a stalagmite corresponds to a layer of growth in the life time of the speleothem and may record the rainfall over periods spanning many seasons to individual storms. Stalagmites, like ice cores, tree rings, mud cores and even human hair, record a detailed record of what the environment was like when they grow undisturbed, sometimes over hundreds of thousands of years. The problem with most ‘proxy’ climate records such as pollen, tree rings etc. is that while they reveal general trends in climate (warmer-cooler, wetter-drier etc) they do not provide hard data (temperatures, rainfall amounts, weather patterns) that the climate modellers (the scientists that provide the all important predictions of the future weather) badly need. Stalagmites are one of the only proxies that have the potential to do this but only if it is known how the cave temperature and groundwater responds to different weather patterns. In 2004 The Royal Holloway University of London in partnership with the GONHS initiated an innovative research program on how a caves really work and how accurately stalagmites record the past climate. The study, supported by the UK Natural Environment Research Council, initially focussed on a small sample of a stalagmite from New St Michaels cave was taken to the hi-tech research laboratories in the Earth Sciences Department at Royal Holloway. Using laser systems and computer controlled micromilling instruments the isotopic record of the sample was investigated at the highest resolution ever made and provided the first ever record of monthly variations in growth of an active speleothem which could be accurately related to the weather above the cave. At the same time data logging systems were deployed in and around the cave, and in the soil horizons above the cave, to record temperatures, humidity, groundwater flow and air compositions. These systems have been managed by the Caves and Cliffs section of GOHNS who also carried out regular monthly sampling of groundwater and air for further analysis. Some of the gadgets needed, such as drip counters, carbon dioxide sensors and loggers were specially designed for this project and have provided data that have never been obtained for a cave system anywhere else in the world. Along with cave monitoring, the project has accrued numerous other firsts, ranging from using the latest techniques for analysing and imaging stalagmites at the European Synchrotron Facility in Grenoble, and resurveying the St Michaels system by precision laser scanning which is producing a highly accurate 3-D computer model of the caves. After four years of hard work we have been able to show that cave monitoring is essential in order to understand the links between weather events and how these are recorded in stalagmites. The results of this research have provided some very interesting and sometimes unexpected results. We have found that cave ventilation is one of the most important controls on stalagmite growth and New St Michaels cave, takes two breaths a Kevin Dixon using a laser scanner to image the Lake Chamber year: it inhales in winter and exhales in summer. This has huge significance to the way stalagmites record climate and was only discovered whilst doing the study. Another important part of the project is understanding the passage of water as rain into the cave. The calcite that forms into a beautiful stalagmite is brought in by rainwater that has picked up carbonic acid as it travels through soil and dissolves rock along bedding planes, and deposits the calcite on the stalagmite has a new layer. Knowing exactly how long it took that rain water to appear in the cave is therefore important. For example, in an area of the cave we have sites just a few meters apart that respond completely differently – one has a response time to rain of only 6 hours others responds far more slowly. At another site water is now known to pass though a siphon type reservoir, indicating that the water is being stored before reaching the cave. All of these different responses measured across 4 years of monitoring have important effects on the way the speleothem grows and records climate. Gibraltar is now at the forefront of this field of research and in February we will be welcoming the cave science community from the US, Australia and all over Europe to discuss monitoring techniques and interpretation of climate records in cave deposits. A highlight of the meeting will be underground visits to see the cave monitoring systems running and gathering data which have now achieved international recognition. References Mattey, D., Latin, J.-P. and Ainsworth, M. Cave monitoring and calibration of a δ18O – climate transfer function in Gibraltar, PAGES Newsletter, 16(3): 15-17, 2008 GIBRALTAR NATURE NEWS 11
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Page 5 and 6: Bufo mauritanicus Phragmites austra
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ure News 11 - Gibraltar Ornithological & Natural History Society

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