Time spent suckling is affected by different social organization in three zebra species

Abstract

Suckling bout duration and frequency were used in the past as an indicator of milk intake. However, later studies found no significant relationship between suckling bout duration and frequency and milk or energy intake. On the other hand recent studies are in line with the suggestion that suckling bout duration and frequency may express intensity of maternal care. The three extant zebra species differ in their ecology and social system. Mountain Equus zebra and Grévy's zebra E. grevyi live in an arid environment, whereas plains zebras E. quagga are found in savannah. Mountain and plains zebra mares form stable herds associated with high aggression and low aggression, respectively. Female Grévy's zebras form loose associations with the lowest level of aggression. The aim of this study was to re‐evaluate the suggestion that suckling bout duration and frequency are affected by social system. We observed suckling behaviour of 30 foals (16 plains zebras, 8 Grévy's zebras and 6 mountain zebras) at the Dvůr Králové Zoo, Czech Republic. We found that suckling bout duration was longest in mountain zebras, followed by plains and Grévy's zebras. Similar results were found for suckling frequency. These results coincide with the rate of aggression among mares; foals spent more time by suckling in species, where more aggression among adults occurred. Thus, the results of our study support the suggestion that suckling bout duration reflects social needs of the foal rather than milk intake requirements.

Strategy of goitered gazelle suckling behavior

“…So, instead, we preferred to use the continued focal animal observation method with an even distribution of watching time throughout the day using binoculars (magnification ×8) and a telescope (magnification ×30-×60). We used suckling duration and frequency as main indicators of the degree of maternal investment (Mendl and Paul 1989;Cassinello 2001;Pluhacek et al 2014), even though neither is believed to reflect the actual volume of milk intake (Cameron 1998;Cameron et al 1999). Even so, we believe that these measurements are still useful indicators of the amount of maternal care invested in fawns (Mendl and Paul 1989;Cassinello 2001;Pluhacek et al 2014).…”

“…In these cases, however, it was not made clear why suckles were not recorded and calculated as they were demonstrated naturally by the animal-taking into account all intervals-instead of producing artificial rules for recording this behavior. Fifth, many authors (Shackleton and Haywood 1985;Gauthier and Barrette 1985;Habibi 1987;Lavigueur and Barrette 1992;Cameron et al 1999;Mauget and Mauget 2009;Pluhacek et al 2010Pluhacek et al , 2014 make the assumption that suckles shorter than 5 s are not really suckling, but rather unsuccessful attempts to suckle, while other researchers define different thresholds for nutritive suckles: 3 s for Oryx dammah (Drews 1991) and 8 s for Ovis canadensis (Festa-Bianchet 1988a, b). Certainly, offspring do not typically receive milk at the moment they begin suckling, but a 5-s interval (3 or 8 s in other versions) has not been determined to be a real threshold for milk transfer and is actually an arbitrary cutoff.…”

Overmarking by adult females in four equid species: social bonds and group cohesion

“…African wild ass ( Equus africanus ) and Grevy's zebra ( Equus grevyi ) exhibit resource defence polygyny, with a fission–fusion social system among females (Klingel, ; Rubenstein, ; Sundaresan et al ., ). As the equid species differ in several ethological aspects according to their social organization (Sundaresan et al ., ; Olléová, Pluháček & King, ; Pluháček et al ., ) and overmarking of two related but socially different mammalian species can differ (Kimura, ; Ferkin & Pierce, ), we predicted there would be differences in overmarking between females of harem dwelling and non‐harem dwelling species.…”

Further behavioural parameters support reciprocity and milk theft as explanations for giraffe allonursing

“…For mothers of various species, lactation may require energy demands that are higher than any other period in the life of the female 4 , 5 . The transfer of milk is an elementary part of reproduction in all mammals, yet species differ considerably with respect to suckling strategies 6 – 8 . Allosuckling (allonursing), which is the suckling (nursing) of non-filial young 9 , undoubtedly belongs amongst the most interesting suckling strategies 10 – 12 .…”

“…Other behavioural parameters are frequently used for the expression of maternal care, and they reflect the offspring’s demand rather than the rate of milk transfer 21 – 23 . These parameters are: suckling bout duration, and/or suckling bout frequency 8 , 24 , 25 . In addition, it was reported that in extreme cases, like allosuckling, these parameters could reflect parent–offspring conflict, as the bout duration may be connected with a shortage of milk, as well as maternal care for filial calves 21 , 22 , 26 , 27 .…”