Male Home Range Size Research Articles

The evolution of leks through female choice: differential clustering and space utilization in six sympatric manakins

The degree to which lekking and non-lekking male manakins select display sites in order to maximise proximity to females was examined by contrasting movements of females with male dispersion. Data on female visiting patterns, male courtship disruption, and mating skew were also collected over three successive breeding seasons. For the five lek-breeding species, female home-ranges were 3–7 times larger than those of adult males. Female movements were concentrated around leks, fruiting places and stream bathing sites. None of the females monitored by radio-tracking expanded her normal range in order to visit males on leks. On the contrary, feeding bouts of females frequently preceded a visit to potential mates at neighboring leks. Despite small sample sizes, significant correlations were found between female home-range size and male clustering (distances between neighboring leks and distances between neighboring males), as predicted by the female choice model and the hotspot model. Adult and immature male home-range sizes were not significantly correlated with male dispersion or female ranges. On the other hand, males and females of the only non-lekking species exhibited similar use of space and home-range size. Male settlement at sites with high levels of female traffic showed that the hotspot model is adequate to explain differences in male dispersion among sympatric lekking species. Comparisons with other studies suggest that apparent female choice could be overidden by past and present male-male interactions or female mate-comparison tactics. In fact, both the hotspot model and the attractiveness hypothesis appear to shape male dispersion on leks: males appear to settle under hotspot conditions with “despotic” rules generated through bias in female choice or male-male interference. It is proposed that the evolution of leks is ecologically motivated by the spatio-temporal distribution of trophic resources, initially leading to a dispersed male-advertisement polygyny. Following this, a foraging ecology that promotes high mobility by females and the magnetic effect of mating skew in particular males may have favored clustering on exploded leks. Later, the development of male-male interference and the increasing female home-range size could have led to the evolution of classical leks.

Deems'e vole love's meed? Hares are level, eraser, ah?

Michael Rosenzweig's (1990) perceptive comment on the paper by Bondrup-Nielsen and Ims (1990) prompted me to look elsewhere for the pattern they describe in voles. The vole pattern is remarkably robust, with one variable, the ratio of female to male home range size, explaining 94% of the variance in the ratio of female to male body size. Where females are larger than males, they have relatively smaller home ranges, and vice versa. Presumably some weight-related dominance effect is responsible, as Bondrup-Nielsen and Ims suggest; if so, I fail to see why the relationship is continuous rather than bimodal. Rabbits, hares and pikas form another uniform group of small herbivores with variable social behaviour, and might be expected to conform to the same pattern if it were widespread. I collected the few studies which document data on body size and home range for the sexes separately (Fig. 1). To qualify, a study had to report data very much like those in BondrupNielsen and Ims: all weights and home ranges were those of adults separated by sex. The data of Fig. 1 show no parallel to the regression line for microtines.

Reversed sexual size dimorphism in microtines: Are females larger than males or are males smaller than females?

We analysed sexual size dimorphism for 21 populations of microtine rodents. Female to male size ratio varied considerably among populations from females significantly larger than males (ratio=1.18) to males larger than females (ratio=0.78). In a multiple regression analysis female to male home range size ratio explained 94% of the total variation in body size dimorphism and was the only one of eight independent variables that was selected in a stepwise regression procedure. When females are the larger sex, males have home range sizes much larger than females. We suggest that the relationship between home range size ratio and body weight size dimorphism reflects different selection pressures on males and females in competition for resources and mates.

Social organization and nest co-occupancy in Peromyscus californicus, a monogamous rodent

Home ranges, social organization, and nest co-occupancy of Peromyscus californicus were studied using radiotelemetry at the Hastings Natural History Reservation, California. Mated pairs were ascertained by the transfer of fluorescent pigments from lactating females to putative fathers. Mated pairs had largely overlapping home ranges that were not statistically distinguishable, whereas adjacent adults had mostly exclusive, statistically distinguishable home ranges. There was no difference in the mean home range of males and females, but mated females tended to have smaller ranges than their mate. Home range size was extremely variable (range: 150–3788 m2) and averaged 1161 m2 across all individuals. Male home range size was inversely correlated with population density, suggestive of a social influence on home range. Putative fathers spent comparable amounts of time to females in the nest — presumably caring for the young — which supports previous laboratory reports of paternal care in this species. All data collected in this study are consistent with previous suggestions that P. californicus live in semi-permanent family groups and are monogamous.

Spacing Pattern, Habitat Use and Survival of Capercaillie in a Fragmented Winter Habitat

Habitat, spacing pattern and survival of Capercaillie Tetrao urogallus were studied in southeast Norway during the winters 1981-87 using 65 radio-marked birds. Adult males (>3.5 yr) preferred old, pine-dominated forests close to their lekking grounds. Subadult males (0.5, 1.5, 2.5 yr) and females (>0.5 yr) were distributed more independently of leks and utilized middle-aged (>7 m) pine plantations besides older, natural forest. Spruce-dominated forests and younger plantations were avoided by all sex/age groups. Home range size of subadult males (98.4 ha) was significantly larger than that of adults (63.5 ha) which was significantly larger than that of females (26.8 ha). During late winter (1 Mar 15 Apr), adult males concentrated within 400 m of leks, subadult males occupied the peripheral zone between 400 and 800 m of leks, and most females stayed further than 800 m away from leks. When leks were only attended by subadult males, such males concentrated within 400 m of lek centres, thus further suggesting that adult males exclude subadults from the vicinity of leks in late winter. Hens retreated to interlek regions with low male density, possibly to avoid male courting interference. Males in highly fragmented habitats stayed farther away from their lekking grounds than males in less fragmented areas during midwinter. Birds living in highly fragmented habitats had larger home ranges and lower survival than other birds.

Home Range Size and Population Dynamics in the Prairie Vole, Microtus Ochrogaster

The relationship between fourteen demographic variables and home range size of three age classes (adults, subadults and juveniles) was studied in two live-trapped populations of Microtus ochrogaster in eastern Kansas, USA. There was a linear negative association between home range size and density for adult females. There was no correlation between these two variables for other age classes. Home range size of adult and subadult males was positively associated with dispersal rate. A Stepwise Multiple Regression and Principal Component Analysis indicated that different demographic variables were important in a statistical sense in explaining variation in home range size for each age class. The interaction between dispersal and home range size is discussed in the context of population regulation of microtine rodents.

Population Ecology of the Lizard Japalura swinhonis formosensis (Sauria: Agamidae) in Taiwan

The population ecology ofJapalura swinhonisformosensis in Taiwan was studied by capture-recapture method from February 1979 to April 1980. The characteristic growth rate of the male lizards is 0.005 mm per day. Male hatchlings of early clutches require 142 days to reach their mature snout-vent length (SVL), those of late clutches 262 days. The characteristic growth rate of the female lizards is 0.004 mm per day. Female hatchlings require 347 days to reach adult size. Growth rates after the third year for both sexes practically cease. Mean home range size of males is 33.47 m2 and is not significantly different between the breeding and non-breeding season. Few home ranges of males overlap. Only large adult males over 73 mm SVL establish territories. Male lizards appear to carry out rout defense concurrently with normal feeding as well as specific site defense. Mean home range size of females is 11.46 m2. Most of the home ranges of females are entirely or partially within those of males. The mating system appears to be polygynous. Monthly population size and survivorship of adult lizards are fairly stable. Mean population sizes of adult males and females are 210.3 and 224.7 lizards per hectare, respectively. Survivorship of males and females is 82.3% and 82.5%, respectively. On the average, second year adult males make up 48.4% of the total male individuals, the third year adult males, 39.0%, and fourth year adult males, 4.1%. Second year adult females make up 28.8% of the total female individuals, third year adult females, 47.1%, and fourth year adult females, 13.4%. Sex ratios indicate that males predominate over females in the first two years, and the opposite is true for third and fourth year individuals. Males and females utilize the habitat horizontally but at different heights; the same is true of the different SVL classes of males. This habitat partitioning results not so much from specialization for food resources, as from the social interactions among males. Perch diameter does not appear to play any significant ecological role.

Seasonal Changes in the Territorial Behavior of the Iguanid Lizard Sceloporus jarrovi

Territorial behavior of Sceloporus jarrovi was observed in Arizona during 3 years. Male aggression, activity and home range size increased and overlap between home ranges decreased as the fall breeding season approached. Most animals defended the entire home range. Males shifted their positions to maximize overlap with females in the fall. Females were less aggressive, occupied smaller areas and shifted positions less.

Ecological Observations on a Texas Population of Six-Lined Racerunners, Cnemidophorus sexlineatus (Reptilia, Lacertilia, Teiidae)

A 35-month mark-recapture study of a six-lined racerunner population was conducted in Brazos County, Texas. A 51/2-month activity season for racerunners in Texas was approximately 1 month longer than that in Kansas. Most females laid 2 clutches per season; some may have laid 3. Mean clutch size was 3.38 eggs. Females attained mature size (68 mm snout-vent length) in time to reproduce at one year of age. Survivorship of racerunners was lower in Texas than in Kansas. Turnover was essentially annual in Texas; life expectancy was shorter for males than for females. Drought in 1971 sharply reduced density of males but did not affect females. Population densities ranged from 24 racerunners/ha in 1970 to 15 racerunners/ha in 1971. Home range size was similar for males and females and averaged 13,099 m2. In 1971 a significant increase in home range size of males accompanied their decreased numbers.

Home-Range Size and Overlap in Sceloporus undulatus erythrocheilus (Reptilia: Iguanidae)

A population of the rock-inhabiting lizard, Sceloporus undulatus erythrocheilus, was studied over two activity seasons in the eastern Colorado foothills. The convex polygon method was used to determine home range and figures were adjusted to eliminate sample size bias. Ninety-seven lizards (53 8 and 44 9) were captured. On the basis of ten or more observations, resident adults (= 50 mm snout-vent length) had an average home-range size of 826 m2 for 12 males and 363 m2 for 9 females. Male home-range size decreased significantly after the breeding season. The large degree of male home-range overlap (52%) suggests that home range is not equal to territory in this population. A promiscuous mating system is implied from the overlap of male and female home ranges and from behavioral notes.

Behavior, Diet and Reproduction in a Desert Lizard, Sauromalus obesus

Chuckwallas living on Black Mountain in the Mojave Desert experienced poor conditions for growth during 1970. After annual plants died and perennials dehydrated in May, the diet of these strictly herbivorous lizards shifted from primarily annuals to perennials only. Chuckwallas stopped eating in late August or September, and entered winter burrows in October after having lost 35% of their body weight during the year. These lizards did not reproduce in 1970, and male home range sizes and aggressive behavior were considerably reduced. Home ranges overlapped extensively, and did not change in size from spring to summer. Chuckwallas were abroad for about eight hours per day in spring, but in summer activity was restricted to about an hour around sunset. Chuckwallas apparently abandon costly social behavior and reproduction in years when succulent food resources are scarce. This may enhance survival of the population during relatively dry years.