Huemul heresies: beliefs in search of supporting data. 3. Reproduction

FLUCK, WT; JM SMITH-FLUECK,

Congreso; 7th International Deer Biology Congress; 2010

The general absence of recovery of remnant huemul populations (Hippocamelus bisulcus) hinges onfactors affecting the population dynamics. We analyze recent published findings about reproductionand behavior with regard to their possible implications. The life history of huemul is characterized byage at maturity of one year with evidence that fawns may also breed. Reports of twinning needconfirmation, but it occurs in congeneric taruca (H. antisensis) and other Odocoilines. Huemul breedevery year and frequently raise fawns successively. Life cycle calculations should apply theseparameters because unrealistic parameters may cover up ongoing processes and lead to spuriousconclusion. Sexual segregation in huemul is facultative, similar to many other cervids and reflectsrelationships between populations and their environment. Dominance group breeding systems weredescribed several times without indications of territoriality, as with taruca. Recently, huemul buckswere characterized as territorial all year, life-long, defending and monopolizing female groups and two‘territorial’ bucks sired most offspring. These two bucks though sired only 26% of fawns in theirrespective social groups. In their area, ‘territorial´ bucks bred about as many wandering females thanresident females, whereas 32-45% of fawns from resident females were sired by outside males.Furthermore, when applying one year as the age at maturity rather than three years, there wereunaccounted fawns and possibly <50% of all neonates were sampled. Overall, these data do not supportterritoriality in huemul. Regarding movements, extant huemul occupy flat grasslands, and at timesnearly exclusively so, while historically huemul occurred up to 270 km from forests and in rollingtopography. The claim that 5 km of open valley inhabited with guanaco (Lama guanicoe) present abarrier to huemul causing genetic isolation is unwarranted: moreover, huemul coexist with guanacocurrently and historically. Erroneously considering landscape features as barriers and underestimatingreproductive capacity may distract from discovering the factors underlaying the lack of recolonizationsgenerally observed in currently reduced huemul populations.