AN IM AL BEHAVIO UR, 1 9 9 8 , 56, 1 3 7 –1 4 6 Art icle N o . ar9 8 0 7 5 7 Resp on ses of aard wolves, Proteles cristatus, Sp arrm an 1783, to tran slocated scen t m arks ALEX AN D ER SLI W A & PH I LI P R. K. RI CH ARD SON Dep artm en t of Zoology & En tom ology, Un iversity of Pretoria (Received 29 April 1997; initial acceptance 17 June 1997; final acceptance 19 October 1997; MS. num ber: 5535R) ABSTRACT W e tested th e d iscrim in ation abilities of aard wolves by m on itorin g th eir resp on se to scen t m arks of m ale or fem ale d on ors varyin g in fam iliarity tran slocated in to th eir territories. W e followed aard wolves in a veh icle an d collected grass stalks with sin gle fresh scen t m arks. Th e n ext even in g we p laced th ese grass stalks at d en s an d m id d en s in th e territory of an oth er aard wolf, wh ich we su bseq u en tly followed for th e wh ole n igh t. Du rin g 43 exp erim en ts 617 stalks were tran slocated . Of th ese, 164 were located by th e an im al followed . Both m ales an d fem ales overm arked m ore freq u en tly, ch an ged th eir d en s m ore often an d in creased th eir scen t-m arkin g rate m ore wh en th ey fou n d scen t m arks of sam e-sex d on ors th an th ose of th e op p osite sex, excep t d u rin g th e m atin g season . Alon g territory bord ers an d at m id d en s, th e m ajority of m arks were sn iffed for sh ort p eriod s an d overm arked . However, aard wolves seld om overm arked m arks at d en s in u se an d sn iffed th em for m u ch lon ger, often sh owin g fleh m en . Fleh m en an d p rolon ged sn iffin g seem ed to in d icate in vestigatory beh aviou rs. Th ey were m ost p revalen t toward s th e first m ark of a n on resid en t fou n d th at even in g an d p articu larly toward s stran gers’ m arks or (in th e case of m ales) th ose of a fem ale d u rin g th e m atin g season . Overm arkin g seem ed to be assertin g territorial own ersh ip . After locatin g a n eigh bou r’s scen t m ark th e resid en t also im m ed iately in creased its rate of scen t-m arkin g an d often wen t d irectly to th e resp ective bord er. Th e resu lts su ggest th at scen t m arks m ay fu n ction in in tim id atin g in tru d ers an d to syn ch ron ize m atin g in th e aard wolf.  ad d ition , scen t m arks m ay be left at territory bord ers to create a ‘wall of sm ell’ to fen d off in tru d ers an d as an in d ivid u ally d istin ctive sign atu re of territory occu p an cy (Gorm an & Mills 1984; Gorm an 1990). Accord in g to th e in tim id ation h yp oth esis, in tru d ers m ay in terp ret scen t m arks as a th reat with im m ed iate p h ysical attack if th ey are en cou n tered by th e resid en t (Rich ard son 1991, 1993). In aard wolves, scen t m arks are assu m ed to attract th e op p osite sex d u rin g th e m atin g season , carryin g in form ation abou t th e rep rod u ctive statu s of th e p rod u cer (Rich ard son 1987a; Sliwa 1996). Th e cap ability for in d ivid u al id en tification by scen t h as been sh own in m an y m am m als both u n d er con trolled con d ition s an d in m ore n atu ral su rrou n d in gs (for a review see Halp in 1986). Paste m arkin g is th e p red om in an t m ean s of scen t com m u n ication in aard wolves (Rich ard son 1990; Sliwa 1996). Th ey often leave a sin gle scen t m ark on a grass stalk th at can be collected an d tran slocated for exp erim en tal p u rp oses. A territorial p air d efen d s a clearly d elin eated territory of 100–600 h a th rou gh overt aggression an d p astin g. Bord ers are d efin ed th rou gh th e con cen tration of scen t m arks in on e area by n eigh bou rin g territory h old ers, an d th eir relu ctan ce to scen t-m ark wh en tresp assin g across Nu m erou s beh aviou ral stu d ies h ave d em on strated th at biological od ou rs serve as cu es in an im al com m u n ication (e.g. see Joh n son 1973; Brown 1979; Mü ller-Sch warze & Silverstein 1983; Brown & Macd on ald 1985). No exp erim en tal stu d y, h owever, h as satisfactorily sh own h ow scen t m arks fu n ction exactly in two socially im p ortan t field s: in territorial d efen ce an d in syn ch ron izin g m atin g beh aviou r. In h yaen id s, scen t m arkin g th rou gh p astin g with an al p ou ch secretion is d istribu ted in p attern s con sisten t with exp ectation s of territory ad vertisem en t (Kru u k 1972, 1976; Mills et al. 1980; Gorm an & Mills 1984; Mills & Gorm an 1987; Rich ard son 1990, 1991; Sliwa 1996). However, p attern s on ly sh ow tren d s, an d th ere is n o con clu sive exp erim en tal evid en ce for h ow wild h yaen id s resp on d to kn own tran slocated scen t m arks. In th e scen t-m atch in g h yp oth esis, Goslin g (1982, 1990) p rop osed th at scen t m arks serve to establish an asym m etry of con test, an d an in tru d er u ses th em to assess th e resou rce h old er’s q u ality in a d irect con fron tation . In Correspondence and present address: A. Sliwa, Hubertusallee 30, D-42117 W uppertal, Germ any (em ail: asliwa@t-online.de). P. R. K. Richardson is at the Departm ent of Zoology & Entom ology, University of Pretoria, 0002 Pretoria, Republic of South Africa. 0 0 0 3 –3 4 7 2 / 9 8 / 0 7 0 1 3 7 +1 0 $ 3 0 .0 0 / 0 1998 The Association for the Study of Anim al Behaviour 137  1 9 9 8 T h e A ssociat ion f or t h e St u dy of A n im al Beh aviou r