Animal Diversity Web

Ge­o­graphic Range

Broth­ers Is­land tu­ataras in­habit North Brother Is­land in Cook Straight, New Zealand (41°06′S, 174°26′E). Only a few hun­dred in­di­vid­u­als re­main on North Brother Is­land. (Cree, 1994; Lutz, 2005; Mitchell, et al., 2008; Thomp­son, et al., 1992)

• Biogeographic Regions
• australian
  • native

• Other Geographic Terms
• island endemic

Habi­tat

Broth­ers Is­land tu­ataras are one of the few rep­tiles with the abil­ity to thrive in cooler con­di­tions. They are noc­tur­nal and phys­i­cally ca­pa­ble of with­stand­ing tem­per­a­tures as low as 9°C, with hu­mid­ity in the range of 70 to 80%. High hu­mid­ity and low tem­per­a­tures allow tu­ataras to main­tain healthy shed cy­cles and live longer life spans, due to their ef­fects on heart and meta­bolic rates. Dur­ing the day, most in­di­vid­u­als in­habit bur­rows along cliff faces. Their bur­rows can mea­sure about 5 me­ters in length and 30 cen­time­ters in depth, and are some­times taken over from pre­vi­ous in­hab­i­tants. Bur­rows are typ­i­cally found in open areas fea­tur­ing low coastal veg­e­ta­tion, and usu­ally offer both shade and sun­light to aid in heat reg­u­la­tion. Cer­tain cliffs and other areas of the is­land that pro­vide dif­fer­ent types of ter­rain are often in­hab­ited by birds or other an­i­mals that can com­pete with tu­ataras for ter­ri­tory. (Cree, 1994; Lutz, 2005; Mitchell, et al., 2008; Nel­son, et al., 2002a; Ram­stad, et al., 2007)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• chaparral

• Range elevation

  87 (high) m

  285.43 (high) ft

Phys­i­cal De­scrip­tion

Tu­ataras gen­er­ally have a lizard-like ap­pear­ance, but dif­fer from lizards in that their teeth are at­tached to bone, they have two tem­po­ral open­ings, they have no ex­ter­nal ear, and the males lack sex­ual or­gans. Tu­atara means “bear­ing spines”, re­fer­ring to the sin­gle row of spines run­ning along their dor­sal side. The skin of this species is gen­er­ally olive-brown with yel­low­ish patches, which of­fers ef­fec­tive cam­ou­flage in their en­vi­ron­ment. When born, tu­ataras pos­sess a third eye on the top of their head (called a pari­etal eye). This pineal spot ap­pears some­what func­tional at birth, but be­comes cov­ered with skin after sev­eral months and does not ap­pear to serve a func­tional pur­pose there­after. Adults are fairly large and rather slow mov­ing, reach­ing a weight of 900 g and a length of 76 cm. Males are larger than fe­males and have pro­por­tion­ately larger heads and crests. (Cree, 1994; Lutz, 2005; Pope, 1956)

Broth­ers Is­land tu­ataras be­long to the order Ryn­cho­cephalia, which con­tains only one other liv­ing species, Sphen­odon punc­ta­tus (spot­ted tu­ataras). Broth­ers Is­land tu­ataras are char­ac­ter­is­ti­cally smaller and have longer re­pro­duc­tive cy­cles than spot­ted tu­ataras. (Cree, 1994; Lutz, 2005; Pope, 1956)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  900 (high) g

  31.72 (high) oz

• Range length

  76 (high) cm

  29.92 (high) in

De­vel­op­ment

In tu­ataras, in­cu­ba­tion tem­per­a­tures above 22°C tend to pro­duce males, while tem­per­a­tures of 20°C and below re­sult in more fe­male off­spring. Young tu­ataras es­cape their eggs by using an egg tooth. This struc­ture is lo­cated on the tip of their head be­tween the nos­trils and is lost after the first cou­ple of weeks. Newly hatched tu­ataras re­sem­ble minia­ture ver­sions of adults, and grow very slowly, tak­ing as long as 35 years to reach adult sizes. (Cree, 2002; Lutz, 2005; Mitchell, et al., 2006; Nel­son, et al., 2002a; Nel­son, et al., 2010)

• Development - Life Cycle
• temperature sex determination
• indeterminate growth

Re­pro­duc­tion

Lit­tle is known about the so­cial struc­ture of mat­ing sys­tems in tu­ataras, but males tend to be highly ter­ri­to­r­ial and mate with mul­ti­ple fe­males if given the chance. Male tu­ataras gen­er­ally out­num­ber fe­males in their na­tive en­vi­ron­ments. Cop­u­la­tion con­sists of a male mount­ing a fe­male and ex­cret­ing sperm from the cloaca. (Cree, et al., 1991; Cree, 1994; Lutz, 2005; New­man, et al., 1994)

• Mating System
• polygynous

Fe­male tu­ataras reach sex­ual ma­tu­rity at 10 to 20 years. Tu­ataras have long life spans and pro­longed re­pro­duc­tive cy­cles. Fe­males usu­ally dig nests in soil lo­cated on cliff edges. Tu­ataras on North Brother Is­land pro­duce an av­er­age of 1.27 eggs per year for each ma­ture fe­male. The mean clutch size of Broth­ers Is­land tu­ataras is ap­prox­i­mately 6.5 eggs. Each egg has a mean weight of 4.9 grams, and the shell has a white col­oration with a rather soft tex­ture. Tu­ataras may lay eggs as often as every 2 years, but most lay eggs every 4 to 5 years. They mate in late sum­mer (De­cem­ber through Feb­ru­ary in New Zealand), with eggs being layed the fol­low­ing spring. (Cree, et al., 1991; Cree, 1994; Hall, 2007; Hemphill, 2012; New­man, et al., 1994)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• oviparous

• Breeding interval

  Tuataras typically breed every 4 to 5 years.

• Breeding season

  Tuataras mate in late summer and lay eggs during the spring. Eggs undergo an incubation period of 12-16 months.

• Average number of offspring

  6.5

• Range gestation period

  8 to 10 months

• Range age at sexual or reproductive maturity (female)

  10 to 20 years

Fe­males in­vest en­ergy in their young via the pro­duc­tion of egg yolks and shells. Once the eggs are laid, nei­ther par­ent pro­tects the eggs. There is also no parental in­vest­ment post-hatch­ing. (Hall, 2007)

• Parental Investment
• no parental involvement

Lifes­pan/Longevity

There is some de­bate re­gard­ing the full ex­tent of tu­atara lifes­pans, but they are known to be able to live for over 100 years. Their longevity is mainly due to their slow me­tab­o­lism and low body tem­per­a­tures. Lit­tle is known about the lifes­pan of tu­ataras in cap­tiv­ity, as they are not gen­er­ally kept as pets. (Lutz, 2005; Nel­son, et al., 2002b; Ram­stad, et al., 2007; Thomp­son, et al., 1992)

• Range lifespan
  Status: wild

  100 (high) years

• Typical lifespan
  Status: wild

  60 to 100 years

Be­hav­ior

The weather plays a role in tu­atara ac­tiv­ity lev­els. Even though they are ca­pa­ble of with­stand­ing lower tem­per­a­tures than most other rep­tiles (as low as 9°C), their ac­tiv­ity level will de­cline in colder weather. There is some de­bate as to whether tu­ataras ac­tu­ally hi­ber­nate, but it is be­lieved that on colder nights they can main­tain a sort of tor­por. Hu­mid­ity on North Brother Is­land is typ­i­cally 70-89%; lower per­cent­ages can re­sult in ac­tiv­ity sup­pres­sion and a pref­er­ence to re­main in bur­rows. (Hall, 2007; Lutz, 2005; Walls, 1983)

Older tu­ataras are ac­tive from dusk until dawn and emerge from bur­rows mostly at night. Young tu­ataras are often di­ur­nal, as their faster speed al­lows them to es­cape pre­da­tion. Older tu­ataras are will set up ter­ri­to­ries that they de­fend with dis­plays or phys­i­cal at­tacks. The most com­monly per­formed ter­ri­to­r­ial dis­plays in­clude for­ward ap­proaches, in­fla­tion of the body, rais­ing of the crest, head bob­bing from side to side, and mouth gap­ing. (Gilling­ham, et al., 1995; Tere­zow, et al., 2008)

• Key Behaviors
• terricolous
• nocturnal
• motile
• solitary
• territorial

• Range territory size

  11.5 to 86.7 m^2

Home Range

De­spite being ter­ri­to­r­ial, tu­ataras typ­i­cally live in close prox­im­ity to each other. Males be­come ag­gres­sive when other male tu­ataras enter their ter­ri­tory. Fe­males will also be­come ag­gres­sive to­wards other fe­males, but often per­mit males into their ter­ri­tory. Ter­ri­tory sizes are 11.5 to 86.7 m^2. Fe­male ter­ri­to­ries are typ­i­cally half the size of males' and in some cases over­lap­ping ter­ri­to­ries can occur be­tween sexes. (Gilling­ham, et al., 1995; Hall, 2007; Lutz, 2005; Tere­zow, et al., 2008; Walls, 1983)

Com­mu­ni­ca­tion and Per­cep­tion

The pupils of the tu­atara read­ily ex­pand and con­tract to help them see di­ur­nally and at night. Al­though they have no ex­ter­nal ears, they are still able to hear. They are also able to use touch, smell, and taste to per­ceive their en­vi­ron­ment. (Lutz, 2005; Naskrecki, 2011; O'Shea and Hal­l­i­day, 2002)

Tu­ataras be­come ter­ri­to­r­ial at about 6 months of age. Males often in­flate their bod­ies, chase off ri­vals, head bob, gape their mouth, and raise their crests in order to de­fend their ter­ri­to­ries. Dur­ing breed­ing sea­son males may croak, which is used as a mat­ing call to alert fe­males to their pres­ence. (Gilling­ham, et al., 1995; Lutz, 2005)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Tu­ataras are car­niv­o­rous and will eat what­ever they can catch. They often prey on bee­tles, worms, lizards, and other tu­ataras. They pre­fer to eat wetas (Dein­crida ru­gosa), an in­sect species that is en­demic to New Zealand. Oc­ca­sion­ally, tu­ataras will eat sea bird eggs lo­cated in bor­rows close to their ter­ri­to­ries. (Hall, 2007; Mitchell, et al., 2008; Naskrecki, 2011; New, 2008)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates
  • insectivore

• Animal Foods
• birds
• reptiles
• eggs
• insects
• terrestrial worms

Pre­da­tion

Sea bird species that in­habit North Brother Is­land some­times at­tack tu­ataras, often for ter­ri­to­r­ial rea­sons. How­ever, swamp har­ri­ers (Cir­cus ap­prox­i­mans) and New Zealand fal­cons (Falco no­vaezee­landiae) are known to catch and con­sume younger tu­ataras. In­va­sive species like rats also pre­date on tu­ataras. Young tu­ataras are di­ur­nal, which, along with their faster speed, helps them avoid being prey to older mem­bers of their species. Tu­ataras may also drop and re­gen­er­ate their tails in order to es­cape pre­da­tion. (Ching, 1986; Lutz, 2005; Meads, 1990; Selig­mann, et al., 2008; Tere­zow, et al., 2008)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • brown rats (Rattus norvegicus)
  • swamp harriers (Circus approximans)
  • New Zealand falcons (Falco novaezeelandiae)

Ecosys­tem Roles

Tu­ataras prey mostly on in­ver­te­brates. As tu­ataras and sea birds may live in close prox­im­ity, tu­ataras oc­ca­sion­ally steal eggs from the birds. The main preda­tors of tu­ataras in­clude birds (Falco no­vaezee­landiae and Cir­cus ap­prox­i­mans), dogs, and rats. A species of tick (Am­bly­omma sphen­odonti) has been doc­u­mented as an ex­ter­nal par­a­site of this species. As the spe­cific ep­i­thet of this tick in­di­cates, it is only found on tu­ataras. (Lutz, 2005; Ram­stad, et al., 2007; Tere­zow, et al., 2008)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Tu­ataras' un­usual phys­i­cal char­ac­ter­is­tics and low pop­u­la­tion num­bers at­tract at­ten­tion and fund­ing from sci­en­tists and con­ser­va­tion­ists. How­ever, there are no known pos­i­tive ben­e­fits of tu­ataras to na­tives of the is­lands where they are found. Al­though tu­ataras are il­le­gal in the pet trade, they have been placed on the black mar­ket for thou­sands of U.S. dol­lars. (Lutz, 2005; O'Shea and Hal­l­i­day, 2002; Ram­stad, et al., 2007)

• Positive Impacts
• research and education

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive eco­nomic ef­fects of Broth­ers Is­land tu­ataras on hu­mans. When threat­ened or han­dled, they are ca­pa­ble of de­liv­er­ing a painful bite. (Lutz, 2005; Ram­stad, et al., 2007)

• Negative Impacts
• injures humans
  • bites or stings

Con­ser­va­tion Sta­tus

Human de­vel­op­ment and in­tro­duc­tion of in­va­sive species on North Brother Is­land ap­pears to have caused the most dam­age to pop­u­la­tion num­bers in tu­ataras. Even though pop­u­la­tion num­bers are low and Broth­ers Is­land tu­ataras ex­hibit a male-ori­ented sex ratio, long-term sur­vival is prob­a­ble. Tu­ataras do not re­pro­duce often, al­though their long life spans helps with their over­all con­ser­va­tion. (Cree, et al., 1991; Hoare, et al., 2006; Lutz, 2005; Nel­son, et al., 2002a; Ram­stad, et al., 2007)

Broth­ers Is­land tu­ataras are pro­tected by the gov­ern­ment of New Zealand. It is un­law­ful to col­lect tu­ataras for pets or kill them for any rea­son. Due to low pop­u­la­tion num­bers, many or­ga­ni­za­tions have rec­og­nized that sci­en­tific re­search on cap­tive tu­ataras is nec­es­sary to con­serve this species and keep their ge­netic di­ver­sity as high as pos­si­ble. Vic­to­ria Uni­ver­sity is ac­tively in­volved in the long-term sur­vival of the tu­atara through stud­ies of cap­tive tu­ataras in­di­vid­u­als. ("Tu­atara Re­cov­ery Plan 2001-2011", 2001; Lutz, 2005)

Translo­ca­tion of Broth­ers Is­land tu­ataras has been at­tempted. How­ever, there is much de­bate as to whether this is the most use­ful method for in­creas­ing their pop­u­la­tion size. Nu­tri­ents and ter­ri­tory on North Brother Is­land are lim­ited and too many tu­ataras might be re­lo­cated in the same place. This could po­ten­tially harm na­tive and new tu­atara pop­u­la­tions. If food and ter­ri­tory are not lim­it­ing, translo­cated tu­ataras ap­pear to adapt well to their new en­vi­ron­ment. ("Tu­atara Re­cov­ery Plan 2001-2011", 2001; Nel­son, et al., 2002b)

• IUCN Red List

  Vulnerable

• US Federal List

  No special status

• CITES

  Appendix I

• State of Michigan List

  No special status

Other Com­ments

A re­cent mol­e­c­u­lar study uti­liz­ing mi­crosatel­lite and mi­to­chon­dr­ial DNA con­cluded that the genus Sphen­odon con­tains only one species, and that Broth­ers Is­land tu­ataras rep­re­sent a ge­o­graphic vari­ant of this more broadly dis­trib­uted species. De­spite this study, many re­searchers and gov­ern­ment agen­cies con­tinue to rec­og­nize Broth­ers Is­land tu­ataras as a dis­tinct species. (Hay, et al., 2010)

The Maori tribe have few leg­ends based on the Broth­ers Is­land tu­atara. Of the peo­ple that sub­scribe to these leg­ends, some be­lieve tu­ataras are bless­ings while oth­ers be­lieve tu­ataras act as omens. (Naskrecki, 2011; Ram­stad, et al., 2007)

Con­trib­u­tors

Amanda Johns (au­thor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor), Rad­ford Uni­ver­sity, Kier­sten Newtoff (ed­i­tor), Rad­ford Uni­ver­sity, Melissa Whistle­man (ed­i­tor), Rad­ford Uni­ver­sity, Je­remy Wright (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

New Zealand De­part­ment of Con­ser­va­tion. Tu­atara Re­cov­ery Plan 2001-2011. Threat­ened Species Re­cov­ery Plan 47. Welling­ton, New Zealand: New Zealand De­part­ment of Con­ser­va­tion. 2001.

Ching, R. 1986. New Zealand Birds: An Artist's Field Stud­ies. Cor­nell Uni­ver­sity: Reed Methuen.

Cree, A. 1994. Low an­nual re­pro­duc­tive out­put in fe­male rep­tiles from New Zealand. New Zealand Jour­nal of Zo­ol­ogy, 21/4: 351-372.

Cree, A. 2002. Tu­atara. Pp. 210-211 in T Hal­l­i­day, K Adler, eds. The New En­cy­clo­pe­dia of Rep­tiles and Am­phib­ians. Ox­ford, UK: Ox­ford Uni­ver­sity Press.

Cree, A., C. Daugh­erty, S. Schafer, D. Brown. 1991. Nest­ing and clutch size of tu­atara (Sphen­odon gun­theri) on North Brother Is­land, Cook Strait. Tu­atara, 31/1: 9-16.

Gilling­ham, J., C. Carmichael, T. Miller. 1995. So­cial be­hav­ior of the tu­atara, Sphen­odon punc­ta­tus. Her­peto­log­i­cal Mono­graphs, 9/1: 5-16.

Hall, D. 2007. The Ul­ti­mate Guide to Snakes and Rep­tiles. Edi­son, New Jer­sey: Chartwell Books, Inc.

Hay, J., S. Sarre, D. Lam­bert, F. Al­len­dorf, C. Daugh­erty. 2010. Ge­netic di­ver­sity and tax­on­omy: a re­assess­ment of species des­ig­na­tion in tu­atara (Sphen­odon: Rep­tilia). Con­ser­va­tion Ge­net­ics, 11: 1063-1081.

Hemphill, K. 2012. DK Eye­wit­ness Travel Guide: New Zealand. Pen­guin.

Hoare, J., S. Pledger, S. Keall, N. Nel­son, N. Mitchell, C. Daugh­erty. 2006. Con­ser­va­tion im­pli­ca­tions of a long-term de­cline in body con­di­tion of the Broth­ers Is­land tu­atara (Sphen­odon gun­theri). An­i­mal Con­ser­va­tion, 9/4: 456-462.

Lutz, D. 2005. Tu­atara: A Liv­ing Fos­sil. Salem, OR: DIMI Press.

Meads, M. 1990. For­got­ten Fauna: The Rare, En­dan­gered, and Pro­tected In­ver­te­brates of New Zealand. Uni­ver­sity of Cal­i­for­nia: DSIR Pub.

Mitchell, N., M. Kear­ney, N. Nel­son, W. Porter. 2008. Pre­dict­ing the fate of a liv­ing fos­sil: how will global warm­ing af­fect sex de­ter­mi­na­tion and hatch­ing phe­nol­ogy in tu­atara?. The Royal So­ci­ety, 275/1648: 2185-2193.

Mitchell, N., N. Nel­son, A. Cree, S. Pledger, S. Keall, C. Daugh­erty. 2006. Sup­port for a rare pat­tern of tem­per­a­ture-de­pen­dent sex de­ter­mi­na­tion in ar­chaic rep­tiles: ev­i­dence from two species of tu­atara (Sphen­odon). Fron­tiers in Bi­ol­ogy, 3/9: doi:10.1186/1742-9994-3-9.

Naskrecki, P. 2011. Relics: Trav­els in Na­ture's Time Ma­chine. Chicago and Lon­don: The Uni­ver­sity of Chicago Press.

Nel­son, N., S. Keall, D. Brown, C. Daugh­erty. 2002. Es­tab­lish­ing a new wild pop­u­la­tion of tu­atara (Sphen­odon gun­theri). Con­ser­va­tion Bi­ol­ogy, 16/4: 887-894.

Nel­son, N., S. Keall, S. Pledger, C. Daugh­erty. 2002. Male-bi­ased sex ratio in a small tu­atara pop­u­la­tion. Jour­nal of Bio­geog­ra­phy, 29/5-6: 633-640.

Nel­son, N., M. Thomp­son, S. Pledger, S. Keall, C. Daugh­erty. 2006. Per­for­mance of ju­ve­nile tu­atara de­pends on age, clutch, and in­cu­ba­tion regime. Jour­nal of Her­petol­ogy, 40/3: 399-403.

Nel­son, N., J. Moore, S. Pil­lai, S. Keall. 2010. Ther­mosen­si­tive pe­riod for sex de­ter­mi­na­tion in the tu­atara. Sym­po­sium: Rep­tile Re­pro­duc­tion, 5/2: 324-329.

New, T. 2008. In­sect Con­ser­va­tion and Is­lands. Springer.

New­man, D., P. Wat­son, I. Mc­Fad­den. 1994. Egg pro­duc­tion by tu­atara on Lady Alice and Stephens Is­land, New Zealand. New Zealand Jour­nal of Zo­ol­ogy, 21/4: 387-398.

O'Shea, M., T. Hal­l­i­day. 2002. Rep­tiles and Am­phib­ians. Penn­syl­va­nia State Uni­ver­sity: Dk Pub.

Pope, C. 1956. The Rep­tile World. Lon­don: Rout­ledge & Kegan Paul Ltd.

Ram­stad, K., N. Nel­son, G. Paine, D. Beech, A. Paul, P. Paul, F. Al­len­dorf, C. Daugh­tery. 2007. Species and cul­tural con­ser­va­tion in New Zealand: Maori tra­di­tional eco­log­i­cal knowl­edge of tu­atara. Con­ser­va­tion Bi­ol­ogy, 21/2: 455-464.

Selig­mann, H., J. Moravec, Y. Werner. 2008. Mor­pho­log­i­cal, func­tional and evo­lu­tion­ary as­pects of tail au­to­tomy and re­gen­er­a­tion in the ‘liv­ing fos­sil’ Sphen­odon (Rep­tilia: Rhyn­cho­cephalia). Bi­o­log­i­cal Jour­nal of the Lin­nean So­ci­ety, 93/4: 721-743.

Tere­zow, M., N. Nel­son, T. Mark­well. 2008. Cir­ca­dian emer­gence and move­ment of cap­tive ju­ve­nile tu­atara (Sphen­odon spp.). New Zealand Jour­nal of Zo­ol­ogy, 35/3: 205-216.

Thomp­son, M., C. Daugh­tery, A. Cree, D. French, J. Gilling­ham, R. Bar­wick. 1992. Sta­tus and longevity of the tu­atara, Sphen­odon gun­theri, and Du­vau­cel's gecko, Ho­plo­dacty­lus du­vaucelii, on North Brother Is­land, New Zealand. Jour­nal of the Royal So­ci­ety of New Zealand, 22/2: 123-130.

Walls, G. 1983. Ac­tiv­ity of the tu­atara and its re­la­tion­ships to weather con­di­tions on Stephens Is­land, Cook Strait, with ob­ser­va­tions on geckos and in­ver­te­brates. New Zealand Jour­nal of Zo­ol­ogy, 10/3: 309-318.