Animals are basically classified into species that permanently occurred in Switzerland, and species that underwent status changes during the monitoring period. A status change is defined as a species disappearing, a species newly arriving, or a species changing its status several times.

Taxonomic Groups	Species numbers in 1900	Numbers of species permanently occurring from 1900 to 2000	New arrivals	Disappearances	Species undergoing several status changes	Net species numbers in 2000
Mammals*	51	49	8	2	0	57
Breeding birds	160	152	19	5	8	173*
Reptiles	14	14	1	0	0	15
Amphibians	18	16	1	0	2	18*
Fishes**	53	49	3	3	1	53
Cyclostomes	2	1	0	1	0	1
Butterflies	191	188	1	3	0	189
Grasshoppers	105	102	1	3	0	103
Dragonflies	65***	62***	3	3	0	65
Total	659	634	37	20	11	674*

Interpretation example
Between 1900 and 2000, 49 mammal species (excl. bats) permanently occurred in Switzerland. Eight new species arrived, two old ones disappeared.

* The total number of species registered in 2000 differs from the number listed for that year in the table below comparing annual data as of 1997 due to the fact that there was not enough conclusive evidence to classify four breeding bird species in the period of 1900-2000. As opposed to the table below, the European Green Toad (Bufo viridis) is not included in the total number of amphibian species in 2000, since according to BDM criteria, it only occurred in Switzerland in 1999 and 2000 rather than during the whole decade of 1991 to 2000. (see complete Z3 datasheet (5.2 MB)).

** Even though the European Eel (Anguilla anguilla) spends a considerable part of its life cycle in this country, it is excluded from this table because it is a migratory species that does not breed here. As a rule. such migratory species are not covered by the Z3 indicator.

*** It is very likely that the Sedgling (Nehalennia speciosa) permanently occurred during the monitoring period . Nevertheless, this dragonfly has not been included in the count for the time being.

Comments
From 1900 to 2000, the overall number of species in the species groups monitored by BDM increased. This development has been particularly marked as regards breeding birds (+13 or rather +17 species; see above) and mammals (+6 species). The number of reptile species increased by one, while the number of grasshopper species declined by two, just as did the number of butterfly species. Cyclostomes lost one species. While some status changes took place among amphibians and fishes, they were mutually offsetting. Species losses were compensated for by gains among dragonflies as well.

All eight new mammal species owe the expansion of their ranges to man. These species were either reintroduced, like the Alpine Ibex (Capra ibex), the Eurasian Lynx (Lynx lynx) and the European Beaver (Castor fiber), or they were released or escaped into the wild, such as the Muskrat (Ondatra zibethicus), the European Mouflon (Ovis musimon), the Raccoon (Procyon lotor), the Siberian Chipmunk (Tamias sibiricus) and the Sika Deer (Cervus nippon). On the down side, the European River Otter (Lutra lutra) died out, and the Brown Bear (Ursus arctos) was hunted to extinction.

Since 1900, 19 new breeding bird species have been recorded in this country, many among them dependent on water bodies.

Switzerland’s 14 regular reptile species were joined by only one new arrival, the Italian Wall Lizard (Podarcis sicula) during that time.
In the monitoring period, one amphibian species was gained, and one was lost. The Marsh Frog (Pelophylax ridibundus) has been released in Switzerland, but the European Green Toad (Bufo viridis) went extinct in the early 20th century. A small population had been reintroduced in the 1990s in the Tessin, but it disappeared again after only a few years. No longer recorded in Switzerland at the onset of the 20th century, the Italian Agile Frog (Rana latastei) was rediscovered in the Tessin in 1982. Hence, it has been fulfilling BDM criteria since 1990. However, it is highly unlikely that the species reimmigrated into Switzerland.

Between 1900 and 2000, three fish species and the European River Lamprey (Lampetra fluviatilis) disappeared from Switzerland’s waters. All these species need to ascend rivers to spawn, which they were no longer able to do once obstacles such as dams had been built.

Among butterflies, only one is considered a new arrival in Switzerland: the Large Copper Butterfly (Lycaena dispar). However, three species have disappeared since 1900.

Restricted to buildings within zoos, nurseries and the like in Switzerland, the Greenhouse Camel Cricket (Tachycines asynamorus) is the one grasshopper species to newly arrive in this country since 1900, while three species have disappeared.

Since 1900, three dragonfly species have immigrated into Switzerland: the Blue Eye (Erythromma lindenii), which established itself as early as 1910, and two later arrivals, the Scarlet Dragonfly(Crocothemis erythraea) and the White-Tailed Skimmer (Orthetrum albistylum). On the other hand, three species disappeared in the last century, namely the Ornate Bluet (Coenagrion ornatum), the Large Pincertail (Onychogomphus uncatus) and the Irish Damselfly (Coenagrion lunulatum).

Dynamics
Among all species groups surveyed, a total of 659 species fulfilled BDM criteria for permanent occurrence in Switzerland in 1900. In 2000, this figure had increased by 15 species, not counting the four bird species mentioned above, the European Green Toad and the Sedgling. In other words, the number of species in the species groups monitored by BDM increased by roughly 2% between 1900 and 2000. This relatively minor increase may be explained by new species gained compensating for old species lost

Development in Switzerland from 1997 to 2008

Overall, species numbers of vertebrates, butterflies, dragonflies and grasshoppers living wild in Switzerland have hardly changed since 1997. Some new species arrived, some established species disappeared. For example, certain bird species were impossible to spot on an annual basis. The Tawny Pipit (Anthus campestris) has been lacking since 1998 (except in 2001), the Little Crake (Porzana parva) could not be found in 1999 and 2002. There has been no breeding evidence of the Curlew (Numenius arquata) between 2002 and 2004 and again as of 2006. The Mew Gull (Larus canus) has not been observed to be breeding between 2003 and 2006. New to occur in Switzerland are one bird species, three fish species and two mammal species: the Bee-Eater (Merops apiaster), the Weatherfish (Misgurnus fossilis), the Topmouth Gudgeon (Pseudorasbora parva) and the Asp (Aspius aspius), as well as the Nutria (Myocastor coypus, also called Coypu) and the Wolf (Canis lupus).

Switzerland	?	1997	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007	2008	Changes from 1997 to 2008
Mammals*	0	57	57	57	57	57	57	58	59	59	59	59	59	2 newcomers
Breeding birds	0	178	176	177	177	177	176	175	174	175	175	177	175	4 disappearances, 3 newcomers, 1 unstable species
Reptiles	0	15	15	15	15	15	15	15	15	15	15	15	15	no change (n.c.)
Amphibians	0	18	18	19	19	18	18	18	18	18	18	18	18	1 unstable additional species
Fishes	0	52	52	53	53	53	53	53	53	53	54	54	55	3 newcomers
Cyclostomes	0	1	1	1	1	1	1	1	1	1	1	1	1	n.c.
Butterflies	0	189	189	189	189	189	189	189	189	189	189	189	189	n.c.
Grasshoppers	0	103	103	103	103	103	103	103	103	103	103	103	103	n.c.
Dragonflies	0	65	65	65	65	65	65	65	65	65	65	65	65	n.c.
Total	0	678	676	679	679	678	677	677	677	678	679	681	682
?species that cannot be classified yet, *excluding bats

Interpretation example
In 1997, 178 free-living breeding bird species were recorded in Switzerland, as opposed to 177 in 2007. The number of free-living mammal species has increased by at least two since 1997.

Comments
As initially mentioned, species numbers have changed only little in monitored animal groups since 1997. However, these figures give no indication as to increases or decreases in population sizes.
Species lists are available for downloading below on this site.

Disappearances
1998: For 15 years, breeding pairs of the Tawny Pipit (Anthus campestris) have regularly been observed in Switzerland. However, it has been impossible to find breeding evidence since 1998.
2002: Very small for decades, the population of the Little Crake (Porzana parva) has decreased even further. This very hard-to-detect species probably no longer breeds in Switzerland on a regular basis.
2003: In the past decades, the breeding population of the Curlew (Numenius arquata)  has gradually declined from more than 60 pairs to zero. While isolated pairs can still be observed in suitable habitats at the beginning of each breeding period, they do not make regular breeding attempts anymore.
From 1966 until 1996, a small island in Lake Neuchâtel harbored a few breeding pairs of the Mew Gull (Larus canus) each year. Widespread in Northern Europe, the species has probably been crowded out by the Yellow-Legged Gull (Larus michahellis) since then. As of 2003, Mew Gulls no longer bred regularly in Switzerland.

Newcomers
1999: The Bee-Eater (Merops apiaster), a southern species, has regularly been breeding in Switzerland since 1991.
1999: The Weatherfish (Misgurnus fossilis) presumably became extinct in Switzerland in the 1950s, the last representatives of the species having lived near Basel. In the early 1990s, the Weatherfish was reintroduced in the Rhone valley, where it has been reproducing naturally ever since.
2003: Also called Coypu, the Nutria (Myocastor coypus) has been occurring in Switzerland since 2003.
2004: Exterminated in Switzerland in the 19th century, the Wolf (Canis lupus) has reimmigrated from Italy in the 1990s. Its occurrence in this country according to BDM criteria was established in 2004.
2006: BDM criteria for permanent occurrence are newly fulfilled by the Topmouth Gudgeon (Pseudorasbora parva), an accidentally introduced fish species.
2007: The Mediterranean Gull (Larus melanocephalus) and the White-backed Woodpecker (Dendrocopos leucotos)fulfill BDM criteria for permanent occurrence.
2008: For the first time fulfilling BDM criteria for permanent occurrence, the Asp (Aspius aspius) has always been very rare in Switzerland. Originally from Central Europe, this fish species may be found throughout the catchment area of the River Rhine.

Unstable species
For a species to be considered unstable, it needs to change its status (occurrence/nonoccurrence) more than once during the monitoring period.
1998 to 2008: After its population size had been dwindling for a long time, the Common Snipe (Gallinago gallinago) no longer fulfilled BDM criteria from 1998 until 2004. Since 2005, however, it is again considered to be a breeding bird species.
1999 to 2000: The European Green Toad (Bufo viridis) was reintroduced in the Tessin, where it had been reproducing since 1991. However, this remained its only occurrence in Switzerland, and it has gone extinct in the meantime.

Sources
Swiss Ornithological Institute, Sempach
Coordination Office for the Protection of Amphibians and Reptiles in Switzerland (KARCH)
Swiss Center for the Cartography of the Fauna (CSCF)
Surveys conducted by Faune Concept and Aquarius on behalf of BDM
BDM surveys

In the past years, both vertebrate species numbers and monitored insect species numbers have remained comparatively stable in Switzerland. Species numbers may change, for example, whenever isolated patch habitats change, affecting or benefiting rare species. But they are also impacted by large-scale developments such as area dislocations (natural changes in range) and accidental introductions. It is generally beneficial for any region to accommodate a large number of species, as long as rare endemic species are not crowded out by new arrivals that are very common to begin with. However, this is not a threat posed by newcomers such as the Nutria, the Bee-Eater or the Weatherfish. Things are not quite as clear, though, as regards the Topmouth Gudgeon. Originating from Asia, this small fish may — in case of mass propagation — become a food competitor for other fish species, especially for fry.

Several regions are being recolonized by species that had either been actively exterminated in those regions or simply lost their habitats. Examples for this development include the Eurasian Lynx, the Common Heron, the Corncrake, the Edible Frog, the Hoopoe, the Wild Boar, and the Wolf. It strikes the eye that the return of large predators in particular will upset existing predator-prey relationships.

Other species, such as the Eurasian Ruffe, the Scarlet Grosbeak, the Black-Necked Grebe, the Black Kite, and the Tufted Duck, have extended their natural ranges into new regions.

Unfortunately, it is still not possible to completely prevent the extinction of endangered species in Switzerland. Losing typical bogland species that used to be rather widespread is a painful failure of Swiss nature conservation. For several species, such as the Curlew, bogland protection measures were initiated too late.

At a regional level, species numbers have been tending to increase in many European areas in the past decades. There are several reasons for this: Firstly, residual populations of endangered species were often saved on the brink of extinction by well-targeted nature conservation efforts; secondly, new species were accidentally or intentionally released into many regions; and thirdly, various reintroduction projects haven proven successful.

Responsible for Z3
Meinrad Küttel, meinrad.kuettel@bafu.admin.ch, +41 (0)31 322 93 24

Additional sources of information
> Federal Office for the Environment FOEN
> Swiss Ornithological Institute Sempach (information mostly in German and French)
> The website of the Swiss Center for the Cartography of Fauna provides access to a wide range of data on animals occurring in Switzerland.
> Detailed information on Switzerland's amphibians and reptiles (in German, French and Italian)

> Complete data sheet Z3 (5 MB)

> List of the species of Switzerland: Mammals (excluding bats): 1997 – 2008
> List of the species of Switzerland: Breeding birds 1997 – 2008
> List of the species of Switzerland: Reptiles 1997 – 2008
> List of the species of Switzerland: Amphibians 1997 – 2008
> List of the species of Switzerland: Fishes and Cyclostomes 1997 – 2008
> List of the species of Switzerland: Butterflies, 1997 – 2008
> List of the species of Switzerland: Grasshoppers and Crickets, 1997 – 2008
> List of the species of Switzerland: Dragonflies, 1997 – 2008