Fotoboek Terrapene carolina major

@ Hi Vince, the german artikel I have to send by post.
I think it explains beter the thought about hibernathing from T c major in captive care as the English artikel.

If you like to read it you can send your home addres in a PM to me and I post it to you.
I copyed the other Englisch artikel here for you to read;

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Thoughts on Multiple-clutching in Gulf Coast Box Turtles: Don’t venture all your eggs in one basket

Marine turtles are known to produce multiple clutches of eggs: loggerheads, Caretta caretta, for example, may nest up to seven times in one summer (Lenarz et al., 1981) and leatherbacks, Dermochelys coriacea, average 7 nests in the years when they reproduce (Safina 2006). However, for individual marine turtles nesting is typically followed by a number of years of no reproductive activity. Annual double clutching is known for a number of tortoises and freshwater turtles of various families and genera, but single clutches appear to be the norm. This is particularly true of temperate North American species, where multiple clutching is known for but a few species. In North American pond turtles (Emididae) triple clutching is reported for some races of box turtles Terrapine carolina (Jackson 1991, Dodd 1997), spotted turtles, Clemmys guttata (Litzgus and Mousseau 2003), and Blandings turtles, Emydoidea blandingii, (pers. obser.), while painted turtles, Chrysemys picta and sliders, Trachemys scripta, can produce up to five clutches per season (Moll 1973, Jackson 1988). Multiple clutching is also known in some species of Asian pond turtles (Fudaka 1965, and Lee and Mulligan 2006). The general pattern in North American pond turtles is that southern populations produce smaller clutches but deposit eggs more frequently than populations of the same species occurring further north. On a species level northern populations are restricted by shorter summers and typically produce large single clutches. In addition, turtles and tortoises at higher latitudes tend to be larger on both population and individual levels, allowing more and bigger females to maximize clutch production and size (Tinkle 1961, Wilbur and Morin 1988, Congdon and Gibbons 1985, Iverson 1992, Willemsen and Hailey 1999, Iverson et al., 1993, 1997, Iverson and Smith 1993). However there are numerous variations to these trends (see discussions by Dodd 2001 and Litzgus and Mousseau 2003). For example, some species of multiple clutching pond turtles do not reproduce every year, and food availability and thereby fitness appears to influence fecundity.

By spreading out the reproductive season over separate nesting events the female turtles decrease the likelihood that the total season’s reproductive output will be consumed by a single predation event (Obbard and Brooks 1981). A protracted hatching period also places a number of distinct size classes of offspring into the system, with the different sizes, or starting dates possibly having survival advantages (response to drought, flooding, food availability, predator search images, and seasonal predators) greater than those from the single clutches. For temperate species early hatching would allow hatchlings to grow prior to hibernation and late hatchlings to get through their first winter on food reserves from absorbed yolks. Thus, multiple clutching may be more important to long-term existence of populations than total reproductive output and would appear to be a selected advantage for conspecifics living at latitudes where prolonged warn seasons allow this behavior to successfully occur.

Based on multiple clutching of captive turtles (Lee and Mulligan 2006) I proposed the question “Is multiple clutching a long-term genetic adaptation, simply an individual’s response to climate, or both?” Based on the reproductive behavior of a captive group of box turtles maintained well north of the area where they originally occurred I can now partly answer this question.

In 2003 the Tortoise Reserve received a group of nine adult Gulf Coast box turtles, Terrapine carolina major (three males and 5 females). These turtles were from the late Dr. Barbara Bonner’s collection where all were very long-term captives each formerly housed indoors (Boston area) under artificial lighting and consistent temperatures.

In May 2004 they were placed in an out door pen (ca 600 square feet) where they were provided with pools and natural cover and substrate. The partly shaded pen is protected from potential predators of the adults and their eggs and young by electric fencing. This captive group is maintained in southeastern North Carolina (ca. Latitude 35 N) approximately 600 kilometers north of the Gulf Coastal Plain areas where these turtles naturally occur (ca. Latitude 30 N). The turtles are kept outside throughout the year, and they hibernate from late October through mid March. During the warmer months they are fed a variety of vegetable and animal foods several times a week and during dry periods the enclosure is watered for several hours as needed with a sprinkling system.

In 2005 these turtles produced their first clutches of eggs. Test nest holes were noted during the early summer and after a heavy rain in early October 36 young were found over a period of several weeks. The young still had egg teeth and several were recovered emerging from nests. In June 2006 after a heavy rain event another group emerged from the 2005 class. While 21 hatchlings were recovered at this time, an unknown number had been consumed by a pair of fish crows, Corvus ossifragus. The crows were seen working the enclosure for several weeks and while only two hatchlings were confirmed as being killed by the crows (mid May 2006), based on the crow’s behavior probably others were also consumed. A single 2005 hatchling, not seen earlier was found in the pen on 28 July 2006. The hatchlings recovered were removed and are being reared in a protected enclosure. The minimal number of young produced by the five females in the 2005 nesting season was 59, with at about 1/3 of the young over wintering in nests. By 6 June 2006 adults in the North Carolina enclosure were again seen digging test holes and laying eggs. (The first nest of the season had six viable eggs.) On 5 October newly hatched young from the 2007 class started to appear.

Gulf Coast box turtles are known to triple clutch, laying 9.25 (Tucker et al 1978) to 10.74 (Jackson 1991) eggs per female/year, and they produce average clutch sizes of 4.5 eggs (Jackson 1991). In 2005 the captive North Carolina group’s total reproductive output was greater (at least 11.8 eggs per female) than what has been previously reported for this subspecies.

Discussion: Gulf Coast box turtles are to some extent an exception to the geographic pattern in overall mass of conspecifics in that as a southern form they are larger than the other subspecies of Terrapine carolina. Because of their greater mass Gulf Coast box turtle females can produce larger eggs and bigger clutches. The resulting young are also larger than hatchlings of the nominate race. Thus, they differ from the general pattern of northern populations being composed of largest sized adults that produce larger clutches. Total reproductive out put, clutch size, and egg size apparently result from a complex of variables. However if one only considers the number of clutches produced annually by individual females, available information indicates that Gulf Coast box turtles, and Florida box turtles, T. c. bauri (Dodd 1997) do fit the pattern of a greater occurrence of multiple clutches than northern conspecifics.

It is interesting to see the last 2005 clutches of our Gulf Coast captives produced young that successfully over wintered in their nests. This is unlikely to take place in natural occurring populations within the sub-species’ native range. It is also worth noting that the adult turtles have all successfully hibernated in a situation where the winters are both longer and colder than they are in their natural range.

The question as to weather or not multiple clutching is a response to living at lower latitudes (longer and warmer periods for adult activity), and prolonged periods of warm temperatures for incubation of successive clutches is in part answered. Despite being long term captives that had not reproduced, or even been given the opportunity to mate because of many years (10 + for all individuals, with some perhaps for over 20 years) in captivity as solitary individuals, and not allowed to experience seasonal changes in day length or temperature these turtles resumed normal reproductive behavior and output in less than 12 months of being housed in an outdoor enclosure. While free ranging and captive eastern box turtles living on the same property produce one to two clutches per year (pers. obser.), the Gulf Coast box turtles reproduced at a rate similar to wild adults occurring within their native, more southern, range. Based on the number of young found in the pen each female must have produced three clutches each having near the reported maximum number of eggs. Thus, while it would appear that their overall greater mass influences their larger clutch size and egg size, that latitude, shorter activity seasons, and changes in day length do not result in shifts lowering the number of clutches produced per female per year.

Because of the successful hatching of multiple clutches at the North Carolina site the question arises as to why our local box turtles do not produce an equivalent number of clutches. Palmer and Braswell (1995) provide information on clutch size for native box turtles in North Carolina, their data combined with information obtained on captive and additional wild individuals from that state (pers. obser.) indicate an average of 3.52 eggs per clutch. While there is no published information on multiple clutches in North Carolina populations the available data is based on dissections and observations of individual nesting events. Multiple clutching does occur on occasion. Double clutching of captive turtles obtained locally shows at least a third of the females double clutch, but triple clutching has not been documented (pers. obser.). The successful multiple clutching of Gulf coast box turtles in North Carolina suggests that this reproductive strategy would not be a wasted expenditure of energy for native (North Carolina) box turtles. The fact that they are not known to regularly produce multiple clutches and do not triple clutch suggests that this aspect of their reproductive behavior was genetically influenced by Pleistocene climates when conditions in what is now North Carolina were colder and damper than those of our modern period.

In addition to whatever academic interest this observation may generate, information on the continued multiple clutching of translocated turtles could be important for conservation efforts as well. Stressed populations for some species which might benefit from increased input of young and immature turtles could be captive bred at secure facilities outside their native range without concern for major changes in reproductive behavior, reproductive output, or negative changes in fertility, incubation success, or survival of adults or hatchlings. Furthermore, it has been suggested that captive box turtles may exhibit an increased and more consistent reproductive output than their wild counterparts while for populations and for individuals occurring in the wild mean clutch size can vary between years. (Cerda and Waugh 1992, and see discussion in Dodd 2001). Therefore captive groups would not only experience lower mortality than free living individuals for all age classes, but total long term reproductive output is likely to be enhanced.

David S. Lee, © 2007 The Tortoise Reserve

Published in Radiata 16(2); 16-22

Acknowledgements: I thank Mike Penko and Chris Bogard for arranging the transfer of the Gulf Coast box turtles from the Turtle Hospital to the Tortoise Reserve and various members of the Florida Turtle and Tortoise Club for their help constructing the pen that houses the turtles.

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