©1998 Jürgen Chlebowy & Martin Hallmen

What makes the San Francisco Garter Snake so desirable?

"Endangered species have their own type of mystique, and the more unavailable a species is, the more it is wanted by hobbyists. When protected status and rarity are combined with beauty, you have a case of instant desire for the unobtainable. Today perhaps the most beautiful, yet unobtainable, North American snake is the San Francisco garter snake." (WALLS, 1995).

This assessment of Jerry G. WALLS from the homeland of one of the most beautiful snakes of the USA (Figure 1) is also true for all snake keepers in Europe. Even if this colorful snake is a little bit more available here than it is in the States.

About this unique snake

The San Francisco Garter Snake Thamnophis sirtalis tetrataenia occurs in different color patterns. But mostly it has a greenish yellow back stripe, red and black stripes along its sides and a green-blue belly (MACK & MOSELEY, 1997). The top of the head is light red (SWEENEY, 1992). This vivid coloring makes these snakes "disappearing" in the bushes, because their outline is disrupted. This Garter Snake is a relatively large one which can grow up to 1.30 m.

The San Francisco Garter Snake requires both a thick and dense vegetation for cover and open areas for basking. According to its diet, which consists mainly of frogs, this subspecies needs to stay close to water.

Actual situation in the USA

The San Francisco Garter Snakes have been sited in 4 areas on the San Francisco Peninsula. All of them are within San Mateo County. The areas are: Pescadero Marsh Natural Preserve, Ano Nuevo State Reserve, Laguna Salada (near Mori Point) and the San Francisco State Fish and Game Refuge. It was never seen in San Francisco (MACK & MOSELEY, 1997).

The San Francisco Peninsula is one of the most developed areas of the California coast. No wonder that Thamnophis sirtalis tetrataenia suffers mostly from loss of habitat. It is threatened by urban and agricultural development and freeway and road construction. But trampling and illegal collection also happen. At the moment there are only 5 populations of the snakes left. The largest known of the recent populations is near the San Francisco International Airport (MACK & MOSELEY, 1997). The introduction of the bull frog (Rana catesbeiana) is the last major problem for the San Francisco Garter Snake. This frog eats the food of the snakes (other frogs) and it is sad to eat young snakes themselves (MACK & MOSELEY, 1997).

The total population of this subspecies is believed to number only 1.500 adult snakes (KAPLAN, 1997). The history of protection of this highly endangered snake is very short and also ineffective. For more information about this read KAPLAN (1997). But as a result most authors do confirm with the prediction of WALLS (1995), that Thamnophis sirtalis tetrataenia will be extincted in nature by the turn of the century.

The beginning in Europa

The first and only San Francisco Garter Snakes (Thamnophis sirtalis tetrataenia) were imported to Europe in 1990/91. Jersey (England) was the place where it got footing in our continent. Because of a successful breeding in 1992 some San Francisco Garters reached the Diergaarde Rotterdam (Netherlands) (VAN HET MEER, pers. information). The snakes also breed there with big success and in 1993 the first offsprings of Rotterdam came into private hands as a loan. Some of the young snakes from Rotterdam were also transferred to the Zoo of Lodz (Poland).

The little number of private breeders of Thamnophis sirtalis tetrataenia, that was lucky to receive snakes from the Diergaarde Rotterdam as a loan, was allowed to sell their offspring legally to other snake keepers with interest. So it only took 7 years to build up an European population of the San Francisco Garter Snake that is pretty large (see below).

The actual European population

The actual number of specimens of Thamnophis sirtalis tetrataenia in Europe is not so easy to find out. Some people seem to transfer the difficult situation resulting from the overprotection in the USA to Europe. In fact a few number of keepers of the San Francisco Garter Snake do not cooperate. They maintain a strict silence about all themes concerning these special snakes. When asked about details of keeping conditions, breeding success or other points of interest they refuse to give any information about the animals kept. So what we only can give is the number of animals which we know for sure. The real number of San Francisco Garter Snakes in Europe can only be estimated.

But on the other hand we do have a lot of personal contacts to breeders of the San Francisco Garter Snake and we think that we can estimate the actual situation sufficiently. Table 1 shows the number of specimens of Thamnophis sirtalis tetrataenia we know in Europe. The total amount is about 90 animals. Poland (40), Germany (23), the Netherlands (15), Austria (4-5) and Switzerland (3) are the countries with the most exact data. It is known that there exist some San Francisco Garter Snakes in England but we don't have any actual information about these specimens. The total number of snakes of this subspecies of Thamnophis sirtalis in Europe we estimate to about 130-140 specimens in maximum.

14 of the specimens mentioned above are kept by members of the EUROPEAN GARTER SNAKE ASSOCIATION (ZERNECKE, 1997). At the moment there are 3 zoos in Europe, that keep Thamnophis sirtalis tetrataenia: The Diergaarde Rotterdam (Netherlands), the Zoo in Lodz (Poland) and the Zoo in Munster (Germany). The breeding group of the Zoo in Jersey (England) was recently sold to an English breeder about whom we unfortunately know nothing.

Breeding problems

As we have explained the total number of specimens of Thamnophis sirtalis tetrataenia in Europe are offsprings of the animals introduced to Jersey. This parietal generation of all San Francisco Garter Snakes in Europe was surely inbred, because it is possible that they all came from the Zoo in Memphis (USA) where only one pair of San Francisco Garter Snakes was kept for a long time (WEISS-GEISSLER & GEISSLER, 1995). So no exchange of snakes took place for a certain period. That means that already our P-generation was probably genetically degenerated.

In the mean time most of the snakes of this subspecies in Europe are minimum F₁₀-F₁₁. No wonder that we start to see increasing problems of inbreeding. The Diergaarde Rotterdam (Netherlands) and the Zoo of Lodz (Poland) produce mainly males. Reports of males dying young are accumulating. Breeding problems become more and more obvious.

The future

Chances to save the San Francisco Garter Snake from dying out in the USA are not even good. Some American snake specialists (WALLS, 1995) see one of the last chances for this subspecies in the little number of snakes kept in Europe. But if we don't get any other blood line in the next years, inbreeding problems will increase more and more and some day the European population of Thamnophis sirtalis tetrataenia will break down. We will not have much time to avoid this fatal development.

For the rescue of this unique snake it is high time for the following measures:

1. All keepers and breeders of the San Francisco Garter Snake in Europe should work together! We need all available data of each single snake in one central data file. It could be hold by a zoo, the EUROPEAN GARTER SNAKE ASSOCIATION or another confident private person. From this data file the inbreeding problems should be organized. So genetic degeneration could perhaps be slowed down and Thamnophis sirtalis tetrataenia could be kept alive in Europe for a certain time under the given circumstances.
2. But the real problem only could be solved with some specimens directly from the USA. Depending on the degree of inbreeding in the zoos these snakes probably must be a wild caught. These snakes could be crossed with our snakes and most of the bad effects of inbreeding would be wiped out soon. If this should not be against the law it is necessary that the authorities in charge in the States will allow a strictly limited export of a few specimens of Thamnophis sirtalis sirtalis. The partner for the authorities in Europe should be the institution or person with all central data of the European population. Incrossing of the new blood line could be organized from here. Maybe some years later the first European babies of the San Francisco Garter Snake could be reimported to their homeland.
3. Irrespective of the import of some specimens to Europe from the US authorities should install and organize a special breeding program with well known breeders that have experiences in this wonderful snake. From our view in Europe it looks like the San Francisco Garter Snake is in a special way overprotected which could have fatal consequences.

The last idle talk in circulation

One of the very few zoos in the USA that has the permission of keeping the San Francisco Garter Snake is very successful in breeding. But while every kind of trade or exchange of this endangered subspecies is strictly forbidden, it is said, that the overproduction of Thamnophis sirtalis tetrataenia is used as food for cobras! No comment about this practice.

Acknowledgements

We thank Karin BERGMANN (Germany) for her help with the translation of this article. Jan VAN HET MEER (Netherlands) gave us some helpful information.

Literature

KAPLAN, M. (1997): Not-So-Common Garters. - The Garter Snake, 1/97: 2-8.

MACK, H. & MOSELEY, E. (1997): San Francisco Garter Snake. - http://www.orecity.k12.or.us/ochs/

species/sanfranciscogartersnake.html.

STANISLAWSKY, W. (1991): The San Francisco Gartersnake - the first experiences in Maintaining. - Zool. Garten, 61(4): 267-270.

SWEENEY, R. (1992): Garter Snakes - Their Natural History and Care in Captivity. - Blandford: 128 pp. London.

WALLS, J.G. (1995): The Problematical San Francisco Garter Snake. - Reptile Hobbyist, 1.4: 88-91.

WEISS-GEISSLER, E. & GEISSLER, P. (1995): Haltung und Vermehrung der San-Francisco-Strumpfbandnatter Thamnophis sirtalis tetrataenia. - Elaphe, 3(4): 13-17.

ZERNECKE, J. (1997): EGSA - Breeding Book News. - The Garter Snake, 4/97: 7.

Zusammenfassung

In den USA wird die derzeitige Population der San Franzisco Strumpfbandnatter Thamnophis sirtalis tetrataenia im Feiland auf ca. 1.500 Tiere geschätzt. Erst 1990/91 kamen einige dieser Tiere nach Europa. Von Jersey (England) wurden 1992 Tiere an den Zoo von Rotterdam (Niederlande) und von dort an den Zoo von Lodz (Polen) abgegeben. Von hier aus kamen 1993 die ersten Tiere in Privathand. Die Autoren verfügen für 1997 über die folgenden gesicherten Bestandszahlen: Deutschland 25, Niederlande 15, Österreich 4-5 und Schweiz 3. Die Europäische Gesamtbestand dieser seltenen Schlangenrasse wird auf maximal 90 Exemplare geschätzt. Nur 12 dieser Tiere sind im Zuchtbuch der EUROPEAN GARTER SNAKE ASSOCIATION registriert.

Da es sich bei den meisten der Tiere um die F₁₀-F₁₁ weniger Ausgangstiere handelt, sind Inzuchtprobleme unübersehbar. Zur dauerhaften genetischen Sicherung des Europäischen Bestandes von Thamnophis sirtalis tetrataenia wird vorgeschlagen, eine zentrale Datenbank über alle Exemplare anzulegen. Von ihr aus könnten die Inzuchtprobleme zumindest besser verwaltet und damit eventuell verlangsamt werden. Doch auf Dauer werden alle 90 Europäischen Tiere und ihre Nachkommen nur überleben, wenn die vorhandene Blutlinie mit Direktimporten aus den USA aufgefrischt werden kann. Die Amerikanischen Behörden werden aufgefordert, die bestehenden strengen Schutzbestimmungen mit einer entsprechenden Ausnahmeregelung zu versehen. Als Ansprechpartner könnten Europäische Zoos, die EUROPEAN GARTER SNAKE ASSOCIATION oder nachweislich erfahrene Privatzüchter sein. Handeln tut not!

The Garter Snake, 1998