I t l
Pine Mart~n]_Martes martes, as a Eurasian Beaver, Castorfiber, Lodge Occupant and Possible Predator
FRANKROSELL
and
BJØRNAR HOVDETelemark College. DepUl11l1ent of Environlllcnlal Science-,. N-3800 Bø, Norway
RoseJl, Frank. and Bjørnar Hovoe, 1998. Pine Marten,Ml/rlesml/rle.~.as a Eurasian Beaver.Cl/slor!iIJer.Imlge occopant and possible preoator. Canaoian Fielo-Naluralisl112(3):535-536,
We trapped Ihree aoull EUnJsian Pine MUltens(Ml/rleS 1I1l/l'Ies) al an earlier trappeo-oul EUnlsiall Beaver(Cl/sIOrjilJer) looge in southem Norway. AI anolher site, Pine Martell feces contailling remains or beaver daws and hair were round out- sioe a beaver looge. Pine Martens apparelltly I'eeo on beavers ano use their abanooneo Inoges as resting silcs.
Key Woros: Eurasian Beaver.Cl/slorjiber,Pine Marten,Ml/l'le.l·nll/rles,looge, Norway.
I I I
'li
Whereas Eurasian Pine Marten (Martes marIes) and Euraslan Beaver (CC/s/or fiber) co-habit the same ecosystems liule has been reported on their relationship. This paper documenls two independent inleractions belween these speeies.
In lale December 1991 and early lanuary 1992, we captured two male and one female adult marlens al an earlier lrapped-out Eurasian Beaver lodge in soulhern Norway (59°25'N, 09°03'E). At that time of year lhere had beell an abrupt drop in lemperalure from
+
2.8°e lo -8.2°e (measured al 0700), and snow deplhs (3-15 cm) nuctuated greatly. Many Pine Marlen foolprinls around lhe lodge the day before lhe first caplure indicated lhal martens used il as a temporary resling site.High thennal conduclance raises lhe energelic costs of thermoregulation in Martes sp. (Iversen 1972; Worthen and Kilgore 198/; Buskirk et al.
1988; Harlow 1994), Both Pine Martens and American Martens (Martes C/mericmw)reduce ener- getic cosls in winter by seeking insulated under- ground resling siles (Buskirk 1984; Buskirk et al.
1989; Brainerd et al. 1995). Resting in an abandoned beaver lodge may have provided Pine Marlens with proleetion againsl cold wealheL
In lune 1997, we found a 25 cm diameter holc in the roof of anolher beaver lodge located 3 km from lhat previously described, The lodge had been occu- pied the previous winler by a beaver family, The enlrances to lhe lodge wcre localed under water.
Aboul 20CI11 in front of lhe hole we found feces of a Pine Manen on a lwig, The feces conlained remains of beaver claws and hair. On lhe basis of the size and shape of lhe remains, lhe 111a1'len had fed on a one-
year-old beaver. No 111\1(1 lirlwigs wcre found seat- tered oulside the hole, which sllggesl thal the beavers had somehow become t.-apped wilhin ils own lodge and had been forced lo cx:eavale a hole from wilhin to gel oul. Fresh tooth marks on lhe Iwigs, inside lhe hole, sllpported !his conclusion. A Vine Manen Illay have entered through this hole and eilher killed or scavenged lhe beaver.
The beaver's aqualic lifcstyle and habil of con- slrllcting partially sublllergeu lodgcs under masses of earth and stieks (Wilsson 1971; Zurowski 11)1)2) has seemingly limiled the nUlllher ul' ils c1Teclive predalors (RoselI and Parker (1)96). RuselI el aL (1996) reviewed the causes ul' morlality ill beaver (Castor spp.), bUl t1id nol mention lhe Pine Marlen as a possible beaver predalor. Neilher does Martin (1994) identify beavers as marlen food ilems, Whereas in this observation il was nol possible to confirm that Pine Marlens prey on beaver, il does establish lhat marlens visil beaver lodges allli feed on this rodent. On lhe basis of size alone, we sug- gest lhal young beavers may be more suseeplihle lo predation. Young beavers Illay be capIlIred on land (Kile et al. 1996), or when left unprotectetl ill lodges lhal are opened by the beaver lhemsel ves or hy bears (U r.fl/s spp.) (TYllrnin 1984; Sm ilh cl al.
1994). A drop in waler leveIs can 'lisa ex pose louge enlrances and render young anilllals more vulnera- ble to predation,
Acknowledgments
We thank S. M, Braincrd. N. Fimreite and 1-1.
Parker for reviewing severai drarts of our Illanu- scripL
536
THE CANADIAN Fl ELD-NATURALISTVol. 112
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Reccived 14 November 1997 AcceptedJ6 March 1998
