Female Preference and Predation Risk Models Can Explain the Maintenance of a Fallow Deer (Dama dama) Lek and Its ‘Handy’ Location

Abstract

We tested the predictions of three models (female preference; hotspot; predator avoidance) on lek formation in the fallow deer population of San Rossore, Tuscany. We collected behavioural observations in two leks and radiotracking data on 67 deer over 7 years. Two deer sub-populations were present in the northern and southern sides of the area, respectively, the two sectors being delimited by a river and including one lek each. Predictions were tested for one lek (SG), located in the south-side where we set up our 7-year radiotracking program. Data from a second lek (FO, north-side) were used to test those predictions which imply the occurrence of multiple leks in the same population. We showed that the majority of females made one single visit to one lek, only during the rut. The lek was located outside areas of higher female traffic and home range overlap, and females increased home range sizes during the rut to reach it. Twilight routes of females never crossed the lek; instead, females walked atypical routes and at a faster pace to reach the lek and mate. The distance between the two leks was higher than the average diameter of female home ranges, and only one lek was present within female home ranges. Males reached the lek one month before the arrival of females, corroborating that lekking is a female-initiated process (females moving towards large clumped male aggregations) rather than a male-initiated process (males moving towards female hotspots). Our results supported the female preference model, and rejected the predictions of the hotspot model. Also, leks were located far from areas with higher predation risk, supporting the predator avoidance model. The position of lek SG resulted ‘handy’ at the sub-population level because of the optimal trade-off between travel costs for females to reach it and avoidance of human predators.

Evolution of ungulate mating systems: Integrating social and environmental factors

“…Explanations for leks, however, are more complex than for other mating systems. Females usually visit the lek and leave it soon after mating, whereas males stay and continue courtship toward other females (Apollonio et al, 2014). The most dominant male usually, but not always, occupies the central territory on the lek (Bro‐Jørgensen, 2011b; Isvaran & Jhala, 2000).…”

“…A number of models have been proposed to explain the evolution of leks in ungulates (Apollonio et al, 2014). The female harassment model (a.k.a., black hole model; Clutton‐Brock, Price, & Maccoll, 1992; Stillman, Deutsch, Clutton‐Brock, & Sutherland, 1996) predicts that the sexual harassment by subadult males leads females to find refuge within a territory held by an adult male, and adult males increase their chance to retain harassed females if they cluster in a lek.…”

“…For instance, leks in topi ( Damaliscus lunatus ) and kob ( Kobus kob leucotis and K. k. thomasi ) were located where the grass on the savanna was shorter and enhanced visibility reduced risk of predation (Gosling & Petrie, 1990), or perhaps allowed females a greater opportunity to exercise mate choice. According to Höglund and Alatalo (1995) and Apollonio et al (2014), multiple explanations of lek formation reasonably coexist, and a single factor is unlikely to explain lek evolution in species with contrasting life histories or those living in different ecological contexts.…”

Female mating tactics in lekking fallow deer (Dama dama): experience explains inter-individual variability more than costs

“…In leks, males aggregate and defend small display territories usually located very close to one another and leks are typically characterised by a strong asymmetry in male reproductive success [3][4][5][6] . Females do not get any resources such as food or parental care from males except their genes, but some authors have argued that females might obtain direct benefits, such as a reduction of transmission of venereal diseases and ectoparasites, or the reduction of social interference 5,[7][8][9] .…”

“…The fallow deer is an ideal species to study lek mating given that this cervid forms large reproductive aggregations, individual behaviour can be easily recorded, and males are easily identifiable by antler shape even in the absence of tags. Most previous field studies concerning leks of fallow deer focused on the covariates of male reproductive success (see 33 and references therein), while there is much less information on female tactics of mate choice 9,14 ; for non-lekking populations and controlled experiments see also [34][35][36][37][38] . As sexual selection is a co-evolutionary process between the two sexes, disregarding variation in females overlooks a key aspect of this process 39 .…”