Sacha Engelhardt

Concordia University
Candidat Ph.D.

superviseur(e): Robert Weladji
Début: 2012-09-09
Fin: 2016-04-01


Suckling and allosuckling in reindeer (Rangifer tarandus): the evolution of sociality and cooperative breeding.
The suckling of offspring from females other than their own mother is referred to as allosuckling. To study the causes and consequences of allosuckling, we will observe captive reindeer, Rangifer tarandus. We will test six hypotheses: (1) kinship, allonursing restricted to kin; (2) reciprocity, mutual exchange of nursing non-offspring between lactating females; (3); milk-theft, calves opportunistically allosuckle; (4) mismothering, misdirected maternal care; (5) benefit hypothesis, allosuckling calves benefit by increasing mass gain; and (6) compensation hypothesis, allosuckling calves compensates for nutritional deficiencies. Allonursing and allosuckling were observed for the first 10 weeks of lactation in a group of captive reindeer composed of 20 to 30 mother-calf pairs. We will collect the frequency, duration and positions adopted during (parallel, perpendicular, and antiparallel) suckling and allosuckling bouts using the scan sampling and the ad libitum methods of data collection. The mothers and their calves were weighed every week. We will assess whether the mass of calves and hinds, the sex of calves, the birth order of calves, the age of hinds and hind social rank, size of enclosures, and supplemental feed explain some of the allosuckling variations in reindeer. We will assess the relative importance of the allonursing hypotheses: milk-theft, mismothering, milk-evacuation, reciprocity and kin selection in an experimental setting.


Cooperative breeding, Allosuckling and allonursing, Ecologie comportementale/Behavioural ecology


1- Effects of levels of human exposure on flight initiation distance and distance to refuge in foraging eastern gray squirrels (Sciurus carolinensis)
Engelhardt, S.C., R.B. Weladji
2011 Canadian Journal of Zoology

2- The Effect of Zoo Visitors on Activity Patterns of Captive African Herbivores
Kalioujny, Tamara
2013 Journal of Biodiversity Management & Forestry

3- Allosuckling in reindeer (Rangifer tarandus): Milk-theft, mismothering or kin selection?
Engelhardt, Sacha C., Robert B. Weladji, Øystein Holand, Covadonga M. de Rioja, Rosina K. Ehmann, Mauri Nieminen
2014 Behavioural Processes

4- Evidence of Reciprocal Allonursing in Reindeer,Rangifer tarandus
Engelhardt, Sacha C., Robert B. Weladji, Øystein Holand, Knut H. Røed, Mauri Nieminen,
2015 Ethology