Last year in this period, while walking on a rocky pasture near Ustrine, a small village of the Cres island that faces the western side of the island, in search for the Mediterranean black widow spider (Latrodectus tredecimguttatus), the entomologist Nediljko Landeka and the botanist Slavko Brana spotted here for the first time the endemic species Iris adriatica (Fig.1).
Described for the first time in 1980 by Trinjastic & al. but, it has been validly published only in 2002, with the scientific name Trinajstić ex Mitić. Since then, this endemic species has been found only in the Dalmatian region around the cities of Zadar, Sibenik, Split, Drnis and Unesic and on the islands of Ciovo, Brac, Kornati and Vir.
Iris adriatica´s flowers can be found in early spring (March-April) in mediterranean and sub-mediterranean meadows, within the “Stipo-Salvietum officinals” (a mixture of Stipa grasses and Salvia officinalis) and the “Festuco-Koelerietum splendentis” (a mixture of Festucaand Koeleria splendens grasses) associations as well as in rocky pastures.
Description: Dwarf, rhizomatous plant, perennial but usually leafless in winter. The stem is short (3-5 cm) and the leaves narrow, straight, sometimes sickle shaped, up to 10 cm long, and 0.5-1 cm wide. The flowers, solitary and large at the top of the stem, can be yellow, purple or violet.
Conservation status: Listed as near threatened in the Flora Croatica Red Book. The wild population is decreasing due to succession of the vegetation – the overgrowth of more dominant species (shrubs) due to the reduced utilisation.
The island of Cres (Fig. 1) lies in the Kvarner Gulf, at the Croatian side of the Adriatic sea. Along with Krk, it is the largest Croatian island – both have an area of about 406 km2 . Rich in biodiversity, it hosts about 1300 plant species, many bird and reptilian species, among them various endangered and protected, of which many endemisms.
Tramuntana is the name given to the northern half of Cres; it is also known as the “head of the island” (or, in Latin, “Caput Insulae”). Situated just slightly above the 45th parallel, Tramuntana is widely covered by a dense forest of deciduous trees such as oaks (Quercus pubescens, Qurcus cerris), ashes, hornbeams, elks and chestnuts. Such abundance of trees is favoured by the peculiar climatic conditions, a mixture of continental and Mediterranean – known also as the submediterranean climate.
This area was once mainly used as a pasture and this activity had an important impact in the architecture of the landscape and in the creation of new components of the ecosystem with peculiar microclimates that enriched the primary biodiversity. The inhabitants of Tramuntana practiced agriculture, raised olive trees and forest harvesting in a sustainable way, which ensured an adequate balance between plant and animal species. Sheep (Fig. 2) were important members of the ecosystem because they ensured the maintenance of the grassland in a natural way, and their carcasses were an important food source for the griffon vulture (Gyps fulvus), which inhabits the nearby cliffs. In the last few decades, the amount of sheep drastically decreased, and this led to the decrease of the number of griffon vultures in the island, since sheep are a crucial component of their food chain.
In the same time, the abandonment of the practice of sheep breeding has caused many changes in the vegetation landscape, since the absence of the grazers has allowed the regrowth of the underbrush, made prevalently of Juniperus oxycedrus, Paliurus spina-christi and Crataegus monogyna.
The interior of Tramuntana is mainly covered by forests, however it is possible to see many scattered open patches with small ponds that are an important source of water for the wildlife; there are also many small areas delimited by dry walls where olive trees and old fruit trees still grow; these are excellent pastures for sheep (Fig. 3 and 4).
What caugt my attention is the strong scent that in the whole island begins to spread starting from March, that is released by a big euphorbian species which starts to flower in this period, the Euphorbia characias subsp. Wulfenii (Fig. 5). Typical of the Mediterranean vegetation, this plant can grow up to 180 cm in height. Even though their flowers attract various insect species (Fig. 6 and 7), like all the members of the Euphorbia species, they produce a toxic white sticky sap, which has been used for treating skin excrescences since ancient times.
The following pictures (Fig. 8, 9, and 11) are just an example of the rich biodiversity of Tramuntana. Starting from early spring, a rich bird concert makes a journey in the area particulary pleasent. The forest is espeically rich in song bird species, owls, the hoopoe, the european nightjar, swifts etc. According to curren estimates, of the 136 bird species present in the island of Cres, 65 of them nest in this area. In the whole island there are 32 autochtonous amphibian and reptilian species, among them the common toad (Bufo bufo), the blue-throated keeled lizard (Algyroides nigropunctatus), the common newt (Triturus vulgaris meridionalis), the yellow-bellied toad (Bombina variegata), the agile frog (Rana dalmatina) and the slow worm (Anguis fragilis). One curios thing is that, in the island of Cres and Losinj there are no venomous snakes and still nobody knows the exact reason.
When I was living in Ližnjan, a small village on the south-eastern side of the Istrian peninsula facing the Kvarner Gulf , I used to go every day for a walk along the sea and the surrounding inland, hosting the typical garrigue and macchia plant communities. That was a quite relaxing way of spending my afternoons – walking my dog and photographing everything that caught my senses. One might think that visiting the same place every day would be quite boring, and indeed it can be so – if one does not pay attention to the little details. After a decade spent photographing nature, I could notice even the slightest changes in the light intensity and direction, and their impact on the way I experience the landscape in from of me.
I especially loved visiting Marlera, a plain area with intact garrigue and macchia vegetation and a paradise for insects and birds.
One beautiful and sunny day in May, I went there for the usual walk along the sea. I was lucky that the sky was so limpid that I could see the Cres and Losinj islands of the Kvarner Sea quite well and even the outlines of the mount Ucka, 80 km distant, were clearly visible. While crossing the garrigue along the way, my attention was caught by the shimmer of a wide whitish carpet spread a couple of square meters in front of me. I was quite astonished, because I´ve never seen something like this before. As I approached it in order to investigate it better, I realised that it was Anthemis tomentosa, or the Woolly Chamomile, in full blossom; that’s a daisy-like species that is very rare in this region. I´ve heard about the presence of this species in this area by two well-known local botanists (Claudio Pericin and Slavko Brana), however I have not been able to find its the exact location, even though I tried many times. In fact, this is a very local species that can be found only in this spot on Marlera and in another one at the tip of the Kamenjak peninsula, but only in Marlera it creates such vast veils of beauty at the border of the jagged and rocky coast. I decided to stay here for a while, take some pictures and enjoy the flowers along with the picturesque view of the navy blue sea and the islands of Cres and Losinj in the background. It was so soothing and pleasant just to be here, walk and mindfully feel my surroundings with all my senses and notice every detail around me. The ripples of the sea, the thousands of blue shades, that sometimes are soft but other times are interrupted by a dark, almost black blue that gives the impression of an abyss, but actually is just Posidonia oceanica, a marine plant which creates dense meadows that appear very dark from the surface. Nature is so rich of opportunities in every moment, so it is important is to be alert, and notice the patterns of colours and shapes, feel the wind, smell the air and sense the temperature.
I decided to come close to the plants and to observe in more detail the flower peps to feel the scent and watch the insects coming – bees, spiders, butterflies, ants etc. Their camomile-like look creates a beautiful contrast with the blue of the sea in the background. Once at home I decided to learn more about this species so I discovered something really interesting in a scientific publication: the essential oils produced by this plant have been tested against Gram-positive bacterial species, and an antibacterial activity has been detected, therefore it has a big potential as antibiotics in medicine and in the cosmetic industry http://www.ncbi.nlm.nih.gov/pubmed/23157016.
While continuing my tour of exploration, I encountered a day-flying moth Zygaena filipendula (Six Spot Burnet) on a Knautia head flower.
The vivid red spots on a dark green metallic background on the fore wings are actually a warning sign for potential predators, indicating that they are poisonous. In fact, their entire body contains cyanogenic glycosides, amino acid-derived toxic substances produced by various plants as a defence mechanism against grazers.
The sequestration of the toxic compounds takes place during the larval stage from their food plants, however they are able to synthesize those products in small amount by themselves.
Another surprise was the quite uncommon orchid species, Anacamptis coriophora (Bug Orchid), known also as Orchis fragranas Pollini (Foto 5), a name still in use by some authors, due to the vanilla-scented flowers. It is a nectar-producing species which attracts honeybees, several bumblebee species and some moths of the genus Zygaena.
Foto 5. Two specimens of Anacamptis coriophora
Photo 5. Two specimens of Anacamptis coriophora
Butterflies of the family Lycaenidae are rather frequent in this period of the year, so I saw various species flying around. Among them I was lucky to be able to catch with my camera the beautiful Silver-studded Blue (Plebejus argus, Photo 6, 7 and 8), the Common Blue (Pollyommatus Icarus, Foto 9 and 10) and the Adonis Blue (Lysandra bellargus, Photo 11).
Plebejus argus is widespread and locally common across Europe, Asia and as far as Japan, however threatened due to habitat reduction in the UK. He has a wide variety of food plants (Calluna, Erica, Lotus, Tymus etc).
Interacts with ants in the larval stages: pupation often taking place in the ant´s nest where they are protected from enemies; in exchange they secrete the honeydew-like liquid which is delicious for ants (mutualism).
It is always associated with Lasius ants and emerging adults are attractive to Lasius workers, a very unusual behaviour because they are normally attacked or ignored by them.
Polyiommatus icarus curiosities:
The larva feeds on plants of the Leguminosae family. These plants are rich in flavonoids which they sequester on their wings in order to increase its reproductive fitness. One study made by Burghardt et al. (2000, 2001) shows that females sequestered flavonoids in their wings 59% more efficiently than males.
According to him, the flavonoids accumulated in the wings by the females is used in visual communication, since flavonoid rich females are more attractive to males than flavonoid-free females.
The chrysalis is olive green/brown and formed on the ground, where it is attended by ants, which will often take it into their nests. The larva creates a substance called honeydew, which the ants eat while the butterfly lives in the ant hill.
The preferred habitat of the Lysandra bellargus (Adonis blue) is calcareous grasslands with hot and dry conditions.
In the 1980s, 70% of their colonies had gone extinct in UK, however recently a dramatic recovery has been observed thanks to increased grazing and warmer temperatures.
One research showed that the sexes prefer flowers with different nectar compositions: males of both generations preferred flowers with high proportions of sucrose and high amounts of total sugar, whereas females preferred flowers with high portions of glucose in their nectar, and, in the spring generation, flowers rich in amino acids.
Flowers visited exclusively by males or females in spring differed significantly in their amino acid composition.
Larvae feed exclusively in nature on the leaves of two host plants, Coronilla varia and Hippocrepis comosa (both Fabaceae).