Table 1: Z6 selection of species (by species group)

Species group	English name	Scientific name	Data series	Population development
Plants	Lake Constance Forget-me-not	Myosotis rehsteineri	1990-2006	positive
	Tall Violet	Viola elatior	1995-2005	positive
	Dwarf Bulrush	Typha minima	1996-2005	positive
	Lake Constance Hairgrass	Deschampsia littoralis	1989-2006	fluctuating
Insects		Dorcadion fuliginator	1986-2007	negative
Amphibians	Italian Agile Frog	Rana latastei	1990-2008	fluctuating
Mammals	Brown Hare	Lepus europaeus	1993-2009	negative
	Greater Mouse-eared Bat	Myotis myotis	1996-2008	positive
	Greater Horseshoe Bat	Rhinolophus ferrumequinum	1995-2008	fluctuating
	Lesser Horseshoe Bat	Rhinolophus hipposideros	2001-2007	positive
Birds	Common Snipe	Gallinago gallinago	1987-2008	negative
	Whinchat	Saxicola rubetra	1989-2008	negative
	Jackdaw	Corvus monedula	1992-2008	fluctuating
	Kingfisher	Alcedo atthis	1990-2008	fluctuating
	Willow Warbler	Phylloscopus trochilus	1980-2008	negative
	Common Tern	Sterna hirundo	1980-2008	positive
	Eurasian Curlew	Numenius arquata	1980-2008	negative
	Lapwing	Vanellus vanellus	1990-2008	negative
	Red-crested Pochard	Netta rufina	1980-2008	positive
	Black-headed Gull	Larus ridibundus	1984-2008	negative
	Nightingale	Luscinia megarhynchos	1990-2008	positive
	Savi’s Warbler	Locustella luscinioides	1980-2008	positive
	Woodchat Shrike	Lanius senator	1990-2008	negative
	Rook	Corvus frugilegus	1980-2008	positive
	Common Stonechat	Saxicola torquatus	1990-2008	positive
	Sand Martin	Riparia riparia	1980-2008	fluctuating
	Corncrake	Crex crex	1995-2008	fluctuating
	Little Bittern	Ixobrychus minutus	1980-2008	positive
	Scops Owl	Otus scops	1990-2008	positive

Plants

Lake Constance Forget-me-not, Myosotis rehsteineri

Interpretation example
Since the early 21st century, the number of inflorescences of the Lake Constance Forget-me-not has increased by more than tenfold within 4 years. The maximum number of 264,893 inflorescences (corresponding to 100% in the chart) was recorded in 2006, while the minimum number amounted to roughly 500 in 1989. Dashed lines connect non-annual surveys.

Comments
• Until 1990, the population size of the endemic Lake Constance Forget-me-not was declining on a massive scale. From the mid 1990s on, the situation improved, and its population strongly increased again.
• Around 1990, a gardener planted out some individual plants. This reestablishment population has increased tenfold since, making up a third of the overall population by 1998.
• The increase in 1998 can also be explained by new sites being added. Because of late flooding, the plants were able to seed extensively rather than being limited to vegetative propagation. Low water levels all year long, particularly in 2003 and the following years, resulted in a very marked increase.
• It is possible to stop the loss of occurrence areas by plant care measures such as controlling competitors and detailed information of the seashore users.

Sources
Land Use Planning Agency of the Canton of Thurgau, Frauenfeld/Switzerland (Mr. Rolf Niederer) and Bureau for Applied Ecology and Landscape Planning, Konstanz/Germany (Mr. Michael Dienst, Ms. Irene Strang)

Birds

Kingfisher, Alcedo atthis



Comments
• The biggest population size was recorded in 2007.
• While frequently subject to considerable fluctuations, Switzerland’s Kingfisher population has long been considered to be stable overall.
• Kingfishers are very strongly affected by extreme winter weather. The low numbers registered in the 1980s must be put down to a series of winters characterized by above-average cold spells. The population collapses recorded in 1991, 1997, and 1999 are the result of harsh winters as well.

Source
Swiss Ornithological Institute, Sempach

Lapwing, Vanellus vanellus

Comments
• In the period under survey, the largest population size was registered at the beginning of the time series in 1990, the smallest in 2005.
• Between 1993 and 1996, Switzerland’s overall breeding population was estimated to consist of roughly 450 pairs.
• Once a very widespread breeding bird in the Central Plateau, the Lapwing has generally been decreasing in numbers for some time.
• While the species is known for its widely fluctuating population, breeding success has been too low to make up for natural losses since at least the 1980s.
• Many clutches are destroyed by farming activities and nest robbers. Dogs or recreational athletes may also cause birds to abandon their eggs.
• Population gaps used to be filled by new arrivals from farther North. But with population declines affecting these regions as well, the number of broods in Switzerland has been decreasing rapidly. Still, it seems to remain stable at a very low level for the time being.

Source
Swiss Ornithological Institute, Sempach

By internationally applied criteria, animal or plant species are considered to be threatened with extinction if, based on the best available data, they are facing an extremely high risk of extinction in the wild in the immediate future (IUCN 2004). Once the last population is gone from a region, that region’s species diversity is reduced. For this reason, the group of endangered species is particularly important for species diversity in Switzerland (cf. also Z3: Species Diversity at National and Regional Level).

The examples presented here show different possibilities for endangered species to develop. Not every threatened species is bound to be further reduced in numbers. Some populations remain stable for years, and others even increase.

It is of crucial importance to understand the factors influencing the population sizes of individual species, since the causes for the population of a single species and biodiversity as a whole to increase or decrease are often one and the same. Even though overall species diversity is more resistant to environmental impacts than individual species, rapid changes in species diversity are possible nevertheless—at least when observed in areas the size of a hectare or a square kilometer. Just like the population sizes of individual species, biodiversity is subject to long-term trends on the one hand, and short-term fluctuations, collapses, or rapid growth on the other.

The examples presented here introduce us to a wide range of possible causes for these phenomena. A large number of species are easily affected by habitat alteration such as changes in land use, climate changes, interactions with other species, but also supportive measures by special species protection programs. It is often a complex combination of several causes that modifies a habitat. This is what makes it so difficult to explain the biodiversity of a certain area or, worse still, predict its development.

Responsible for Z6
Meinrad Küttel, meinrad.kuettel@bafu.admin.ch, +41 (0)31 322 93 24


Further sources of information

Plants
> species protection sheets

Insects
> SEG

Amphibians
> karch

Mammals
> publications on Horseshoe Bats
> search for the Lesser Horseshoe Bat
> Swiss Ornithological Institute, Brown Hare data

Birds
> Swiss Ornithological Institute
> SVS / BirdLife Switzerland

General information
> Federal Office for the Environment FOEN
> background information and internet databases for (inter)national plant and animal Red Lists of the IUCN