Natal Range Research Articles

Mating Patterns and Bt Resistance: The Case of the European Corn Borer

Mating Patterns and Bt Resistance: The Case of the European Corn Borer

RESEARCH NOTES: LONG-DISTANCE DISPERSAL BY A SUBADULT MALE COUGAR FROM THE BLACK HILLS, SOUTH DAKOTA

Dispersal is the movement of an animal from its natal range upon reaching age of independence (Bekoff 1989). While subadult (i.e., prepubescent individual independent of its mother's care; Logan and Sweanor 2001) female cougars (Puma concolor) tend to be philopatric, subadult male cougars generally disperse greater distances (Anderson et al. 1992, Sweanor et al. 2000). This phenomenon occurs in cougars at 10-33 months of age (Hemker et al. 1984, Maehr 1990, Ross and Jalkotzky 1992, Beier and Barrett 1993, Sweanor et al. 2000) and has been suggested to take place due to competition for resources and avoidance of inbreeding (Logan and Sweanor 2001). Dispersal movements have been documented in most

AUTUMN DISPERSAL AND WINTER RESIDENCY DO NOT CONFER REPRODUCTIVE ADVANTAGES ON FEMALE SPRUCE GROUSE

Abstract Many, but not all, juvenile Spruce Grouse (Falcipennis canadensis) disperse from their natal range in autumn. In spring shortly before breeding, some of these autumn dispersers will disperse a second time from their winter range, whereas others make their first dispersal from natal range. I postulated that dispersing first in autumn provides greater experience on a potential breeding area than immigrating to the breeding area in spring. I predicted that autumn-immigrant females would show a higher percentage of females nesting, would nest earlier, and would produce more juveniles into late summer than would immigrants in spring. Data were available for females on three areas widely spaced across their geographic range. Immigrants contributed most to production. Parameters did not vary greatly among study areas. Combining all areas, 68% of autumn immigrants and 69% of spring immigrants were known to nest, mean hatch dates relative to the annual median differed by less than 1 day, and spring immigr...

Proximate and ultimate causes of dispersal in the Iberian lynx Lynx pardinus

Most studies on the causes of animal dispersal focus on species of birds or small mammals, but there are few such studies on solitary carnivores. A complete picture of the causes of animal dispersal is not possible without considering cases on a representative set of animals. The Iberian lynx is a medium-size, solitary carnivore that inhabits metapopulations, where dispersal plays a prominent role. Between 1983 and 1998 we studied the proximate and ultimate causes of dispersal in Iberian lynx in the Donana metapopulation (southwestern Spain), based on radio-tracking of 49 individuals. Saturation of limited breeding areas in this small population leads to high dispersal rates in both sexes. Most lynxes dispersed from their natal area between 12 and 24 months of age. Males younger than 1 year old tended to disperse in a higher proportion than females of the same age. However, high dispersal rates for both sexes by the age of 2 years and the lack of differences in the dispersal distances do not support inbreeding avoidance as an ultimate cause of dispersal. Dispersal mainly started between January and June (24/29 cases), when most social interactions occur, which supports the social subordination hypothesis. Lynxes left the natal range at an earlier age from the local population with higher density, which supports intraspecific competition for resources as a cause for dispersal. However, prey seems not to be the limiting resource because dispersal mostly started during the season of increasing prey density, and individual probability of dispersal increases with prey density in the natal area. Dispersers suffered higher mortality than nondispersing lynxes of the same age, due mostly to anthropogenic causes. About half of the dispersers successfully settled in a territory at distances that differed between areas of origin, but not between sexes. Distances reached, shorter than those reported for other similar-size solitary felids, are limited by anthropogenic barriers that prevent connection with closer metapopulations. Key words: dispersal rates, lynxes, Lynx pardinus, resource competition, settlement, social subordination, survival. (Behav Ecol 15:31-40 (2004))

Reduced dispersal and opportunistic territory acquisition in male lions (Panthera leo)

AbstractLife‐history patterns in lions Panthera leo living in savanna woodlands of the Kruger National Park, South Africa, were investigated and compared with those of the Tanzanian ‘plains‐like’ ecosystems (e.g. Serengeti Plains and Ngorongoro Crater). First, lower levels of mortality in the juvenile age classes were found in Kruger lions, which in turn, extend the inter‐birth period. A further difference was a prolonged period of association of sub‐adult males with their natal pride, either directly or in a land tenure system that has not been described previously. Most (80%) of young male coalitions rather than becoming nomadic, remained close to their natal territory after leaving the pride, either as non‐territorial sub‐adults or adults and even as territorial adults. Only 20% of coalitions did not stay close to their natal range, one of which acquired a territory 20 km away from its natal pride. The pattern of territory acquisition, in fact, was one in which the majority of holders acquired territories close to their natal ranges. These behaviour patterns contrast markedly with those from ‘plains‐like’ ecosystems where dispersing males usually move far away from their natal pride's range (>200) km and often remain nomadic for extended periods of time. Dense bush and access to sufficient prey resources in the form of resident buffalo Syncerus caffer herds may be important factors allowing extended residence near the natal pride's territory. Buffalo were more available in our study area habitat than in neighbouring habitats, and comprised the majority of male lion kills. Extended male residence contrasts markedly with current theory on dispersal in polygynous mammals, which holds that only one sex (females for lions) gain an advantage by staying close to the territory of their natal pride. In Kruger it seems that both sexes gain an advantage by not dispersing far, and use currently undocumented mechanisms to avoid inbreeding.

The hidden matrilineal structure of a solitary lemur: implications for primate social evolution.

Kin selection affects many aspects of social behaviour, especially in gregarious animals in which relatives are permanently associated. In most group-living primates with complex social behaviour, females are philopatric and organized into matrilines. Models of primate social evolution assume that females in solitary primates are also organized into matrilines. We examined the genetic structure and the mating system of a population of Coquerel's dwarf lemur (Mirza coquereli), a solitary primate from Madagascar, to test this assumption. Our genetic and behavioural analyses revealed that this population of solitary individuals is indeed structured into matrilines, even though this pattern was not predicted by behavioural data. Specifically, females sharing a mitochondrial DNA haplotype were significantly clustered in space and the average genetic and geographical distances among them were negatively correlated. Not all females were philopatric, but there is no evidence for the successful settlement of dispersing females. Although not all adult males dispersed from their natal range, they were not significantly clustered in space and all of them roamed widely in search of oestrous females. As a result, paternity was widely spread among males and mixed paternities existed, indicating that scramble competition polygyny is the mating system of this species. Our data therefore revealed facultative dispersal in both sexes with a strong bias towards female philopatry in this primitive primate. We further conclude that complex kinship structures also exist in non-gregarious species, where their consequences for social behaviour are not obvious.

DISPERSAL PATTERNS OF SAN JOAQUIN KIT FOXES (VULPES MACROTIS MUTICA)

We investigated dispersal patterns of San Joaquin kit foxes (Vulpes macrotis mutica )o n the Naval Petroleum Reserves, California. Of 209 juvenile kit foxes monitored during 1980‐1996, 33% dispersed from their natal territory. Significantly more males (49.4%) than females (23.8%) dispersed, and dispersal peaked in July. Dispersing males tended to be heavier than philopatric males; philopatric females were significantly heavier than dispersing females. Expressed as a percentage of all juveniles monitored, annual dispersal ranged from 0% to 79% for males, 0% to 50% for females, and 0% to 52% for all foxes. Percentage of male dispersal was related weakly to mean annual litter size (r 2 5 0.27), and percentage of female dispersal was weakly and inversely related to annual indices of smallmammal abundance (r 2 5 0.46). Most (65.2%) dispersing juveniles died within #10 days of leaving their natal range. Survival tended to be higher for dispersing males than for philopatric males but was similar between dispersing and philopatric females. Sixty percent of all foxes that survived to breeding age reproduced except among dispersing females, none of which reproduced. Alloparental care did not account for sex-biased dispersal in kit foxes. Auxiliary adults were observed occasionally with mated pairs, but helping behavior was not observed. Dispersal patterns of kit foxes may be a function of innate sex-biased

Home range shifts by breeding female Townsend's voles ( Microtus townsendii ): a test of the territory bequeathal hypothesis

Numerous accounts of partial or complete breeding dispersal by adult females reported in the literature on microtines have been interpreted as maternal bequeathal. However, for most species, no causal relationship between a female's movements between successive litters and the settlement of her offspring in the natal range has been demonstrated. I tested predictions from the bequeathal hypothesis using data from an intensive study of Townsend's voles where genetical relationship had been determined by marking most pups in the maternal nest before weaning. After correcting statistically for temporal changes in the distance moved between successive litters I rejected the following predictions: (1) that females with one or several daughters of reproductive age should be more likely to disperse or disperse farther between successive births than females without such daughters; (2) that mothers should be more likely to bequeath their range to their daughters in spring when the latter would gain most from having ready access to a breeding range; (3) that daughters benefit from their mother abandoning the natal range through an increase in their probability of recruitment; and (4) that daughters actually use the home range vacated by their mother. I critically reassess the empirical studies quoted as evidence that breeding dispersal is a form of parental investment in microtines and other mammals. Most empirical studies cited in support of the bequeathal hypothesis often only contain anecdotal reports of movements by breeding females or do not mention it as one of its possible adaptive functions. Some studies contain evidence only consistent with the bequeathal hypothesis whereas others are incompatible with this explanation. Documented evidence of bequeathal comes exclusively from species which rely on a semi-permanent resource such as a midden, mound or burrow. I conclude that there is no indication from Townsend's voles or any other microtines that females abandon their breeding range to their female offspring as a form of parental investment.

Dispersal of Juvenile Cougars in Fragmented Habitat

There is little information on the spatiotemporal pattern of dispersal of juvenile cougars (Felis concolor) and no data on disperser use of habitat corridors. I investigated dispersal of radio-tagged juvenile cougars (8 M, 1 F) in a California landscape containing 3 corridors (1.5, 4.0, and 6.0 km long) and several habitat peninsulas created by urban growth. Dispersal was usually initiated by the mother abandoning the cub near an edge of her home range. The cub stayed within 300 m of that site for 13-19 days and then dispersed in the direction opposite that taken by the mother. Mean age at dispersal was 18 months (range 13-21 months). Each disperser traveled from its natal range to the farthest part of the urban-wildland edge, Dispersing males occupied a series of small (<30% the area used by ad M in the same time span), temporary (10-298 days) home ranges, usually near the urban-wildland interface, and often with its longest border along that edge. Each of the 3 corridors was used by 1-3 dispersers, 5 of the 9 dispersers found and successfully used corridors, and 2 dispersers entered but failed to traverse corridors. Dispersing cougars will use corridors that are located along natural travel routes, have ample windy cover, include an underpass integrated with roadside fencing at high-speed road crossings, lack artificial outdoor lighting, and have <1 dwelling unit/ 16 ha

Survival and lifetime reproductive success in dispersing and resident red squirrels

Dispersal in red squirrels (Sciurus vulgaris) is not sex-biased and strict philopatry is rare. The immigration pattern suggests that nearly all animals have to disperse away from the natal site and that dispersal in this species is the outcome of local (intrasexual) competition. If this interpretation is correct, we predict that dispersers and residents, of both sexes, should have equal survival rates and lifetime reproductive success. Body mass, longevity, reproductive success and dominance rank of 34 resident offspring (settling within 400 m of the natal range) and 70 immigrants (dispersers) were compared. Immigrants did not weigh less than residents as adults, nor did they have a higher mortality during the pre-setding period. Survival rate, lifetime reproductive success (females) and the proportion of males obtaining a high dominance rank were similar for residents and dispersers, and no sex effect was found on either of the parameters studied. These results are consistent with the hypothesis that local competition determines whether an individual disperses further away or settles close to its birthplace.

Effect of supplemental food on the dispersal of youngPeromyscus maniculatus

We used experimental provisioning of food and mark-recapture techniques to test the prediction that food supplementation results in increased philopatry by young-of-the-year Peromyscus maniculatus. Resident mice born to known dams on control and food-supplemented grids had their dispersal distances estimated based on the linear distance between the geometric centres of their mothers’ home ranges and those of their own. Mice whose home ranges overlapped or abutted their mothers’ ranges were considered philopatric; otherwise they were considered dispersed. Compared to control populations, food supplementation did not result in increased philopatry by young-of-the-year mice, perhaps because philopatry was already high on control grids. Food supplementation permitted greater movement of young within their natal range and lead to increased residency of immigrants from surrounding areas.

Dispersal in a Monogamous Rodent, Peromyscus Californicus

In view of theoretical interest in the relationships between mating systems and dispersal patterns and the paucity of empirical data on dispersal in monogamous mammals, I studied natal dispersal in the monogamous rodent Peromyscus californicus. Genealogical relationships were determined using fluorescent pigment transfer and DNA fingerprinting, and dispersal distances were determined using dispersal fences and intensive trapping. Minimum dispersal distances were greater for females than for males. Philopatric males (those settling within one home—range diameter of their birth site) tended to be from smaller litters than non—philopatric males. Minimum dispersal distances of males were positively associated with natal litter size at weaning, whereas minimum dispersal distances of females were positively associated with number of sisters in the natal litter. These results suggest that intrasexual mate competition drives female dispersal, while resource competition drives male dispersal. Males remain closer to their natal range than females, most likely to acquire and defend resources to attract females. Peromyscus californicus is unusual among mammals in displaying both a monogamous mating system and female—biased dispersal.

Spatial Integration of Maturing-Male White-Tailed Deer into the Adult Population

We monitored range-use patterns of 15 male white-tailed deer (Odocoileus virginianus) orphaned as fawns (<12 months) and 19 males maturing with their mothers. Survivors were radiotracked until they were ≥30-months old. Some males did not change their natal range, whereas others extended it, dispersed from it, or made occasional excursions. Dispersals could be classified as gradual short-distance or abrupt long-distance movements. Orphaned males maintained greater affinity for their natal ranges than did non-orphans, but had seasonal ranges that were larger on average until 18 months of age. Common use of range between non-orphans and their mothers ceased as males matured and all but one dispersed. The multiple-response permutation procedure successfully was used for the analysis of range fidelity over time or between individuals as an alternative to range-overlap estimates. The results support the hypothesis that dispersal evolved as a means to reduce the chance of inbreeding; the inclusive fitness of mothers may benefit most from dispersal of their male offspring, leading to a situation in which mothers force their male offspring to leave.

A test on social behavior as a cause of dispersal of spruce grouse

Social behavior is one hypothesized cause for dispersal. We tested this hypothesis on spruce grouse (Dendragapus canadensis) in two years by removing adults in summer and monitoring emigration of juveniles in autumn. Despite the absence of adults, juveniles emigrated from the natal range at rates comparable to juveniles on control areas. Data on density and dispersal from earlier spruce grouse studies are reviewed, which show that emigration is constant despite substantial differences in density, and that a clear female sex bias occurs across a wide range of densities. Results do not support the hypothesis that social behavior influences dispersal nor do they support a prediction of the “Oedipus hypothesis” that no sex bias occurs in polygynous birds.

Ozone climatology at Natal, Brazil, from in situ ozonesonde data

Results are presented from analysis of a large ozone profile data set obtained from balloon ozonesonde soundings made at Natal, Brazil (6°S, 35°W) during the last 10 years (1978–1988). The measurements have been made through an Instituto Nacional de Pesquisas Espaciais (INPE)/NASA long‐term collaboration program. The balloons were released by the Brazilian Air Force at the Natal rocket range. The data set is sufficiently large to provide useful climatology on the average ozone concentration behavior and its seasonal variation. The day‐to‐day ozone concentration variability in the troposphere is rather large, giving standard deviations of about 30–40% for seasonal averages. Maximum ozone concentrations occur during local spring, September–October, and minimum concentrations during late autumn, April‐May. The seasonal variation in the troposphere is much larger than in the stratosphere. If there were no seasonal variation at all in the stratosphere, the seasonal variation observed in the troposphere alone would be strong enough to drive a total ozone column variation of about 5%, which is about one half the size of the variation observed in the Natal Dobson spectrophotometer data. The ozone concentration at Natal increases with height between the surface and about 500 mbar, almost linearly, from about 15 parts per billion by volume (ppbv) to about 38 ppbv, in autumn. For the spring average the ozone concentration increases from about 25 ppbv at the surface to about 66 ppbv at 500 mbar. The sonde data suggest that limitations in aneroid pressure sensors used until 1986 caused the Natal sondes to indicate too much ozone above 6 mbar. Because of the relative sparsity and uneven distribution in time of the ozone soundings, the data are not adequate to study ozone trends. The Dobson data time series shows no definitive ozone trend but displays a pronounced quasi‐biennial oscillation in ozone.

Isotope and geochemical constraints on Proterozoic crustal evolution in south-eastern Africa

Proterozoic exposures south of the imbricate thrust terrane in the eastern sector of the Namaqua-Natal Belt of southern Africa are dominated by granitoid plutons intrusive into older supracrustal gneisses. Many of these granites have geochemical characteristics similar to “A-type” and rapakivi suites, as previously described in Australia and the northern hemisphere. Ages obtained from the Natal units range from ∼1.1 to ∼0.88 Ga. Nd TDM values cluster about ∼1.4 Ga. The oldest granitoids have “volcanic arc” chemical signatures but, subsequent to ∼1.1 Ga, “A-type” granites are common. This suggests a change in tectonic environment or melting process at about this time. Initial 87Sr/86Sr ratios and ϵNd values for the older suites approach values normally associated with a depleted mantle reservoir whilst μ values are similar to those found in “orogen” environments. These data clearly indicate that the Proterozoic crust of south-eastern Africa was not derived by extensive reactivation of Archaean or Early Proterozoic protoliths. Low 87Sr/86Sr ratios in metasedimentary carbonates and ∼1.8 Ga Nd TDM ages for metapelites from the Belt support this model and preclude the formation of the Belt in an intracratonic setting. All the data thus support models involving substantial crustal accretion and differentiation, primarily subsequent to ∼1.5 Ga.

Kinship and Origin Effects on Dispersal and Space Sharing in Clethrionomys Rufocanus

An experimental population of Clethrionomys rufocanus with known kinship and life history was established by introducing adult females together with their newly weaned litters onto an island. Dispersal and space use by individual voles were studied by radiotelemetry and intensive live—trapping. Dispersal occurred in relation to the process of sexual maturation. Males matured and dispersed later than females. Dispersal was highly male biased. No mature males remained at their natal site, whereas more than a third of the females were philopatric and reproduced in their natal range. Litter sex ratio accounted for 79% of the total variation in dispersal tendency among young females. Females originating from litters with a male—biased sex ratio had the greatest tendency to disperse. Dispersal in males was not related to litter sex ratio or to three other origin variables that were included in the analysis. Space sharing occurred mainly among philopatric females. Females that dispersed generally avoided contact with other females. Philopatry, coupled with general sociability rather than selective sociability among kin, was probably responsible for the occurrence of extensive space sharing between certain females. Since males dispersed in the absence of obvious external cues, dispersal is most likely triggered by some inflexible physiological mechanism in this sex. Differential exposure to andrigens during prenatal life could possibly explain the great variation in dispersal and space—sharing tendencies among females.

Dispersal Distance, Home-Range Size and Population Density in the Red Fox (Vulpes vulpes): A Quantitative Analysis

(1) Fox capture-mark-recapture studies were reviewed to obtain standardized information on straight-line recovery and dispersal distances. The term recovery distance is used to include all recoveries, but dispersal distance only includes those animals known to have dispersed from their natal range. Data on fox home-range size and population density from these studies are also summarized. (2) The relationship between fox home-range size and population density was investigated, and a regression equation with an inverse relationship was considered to be the most realistic to explain the observed data. (3) Distance moved was correlated positively with home-range size and negatively with population density. Regression equations relating the mean distance moved by male and female foxes to home-range size are presented. (4) The distributions of observed fox recovery distances were examined and modelled. Most distributions showed that the majority of foxes do not move far, but that a small proportion move much greater distances. (5) The relationships between fox population density, home-range size and dispersal and recovery distance are discussed, as is the application of the quantitative relationships to spatial models of fox and fox/rabies population dynamics.

The Evolution of Sex-Biased Dispersal in Lions

AbstractMost female lions remain in their natal pride for their entire lives, but about a third emigrate before they reach four yrs of age. Most emigrating females leave either when they are evicted by an incoming male coalition or when the adult females of their pride give birth to new cubs. One cohort of females left because they avoided mating with males of their father's coalition. Cohorts of dispersing females leave together and form a new pride whose range almost always includes at least part of their natal range. Females that leave their natal pride suffer reduced fitness: dispersing females in the Serengeti first breed at a later age than non-dispersing females and dispersing Ngorongoro females suffer higher mortality. Dispersal patterns of large and small cohorts are such that pride size rarely exceeds or goes below the range of sizes that confers the maximum reproductive success per female. Pride fissions have no consistent effect on the average levels of genetic relatedness within prides. All males leave their natal pride. Most leave at a male takeover, but one male cohort was evicted by their fathers whereas several others left voluntarily during their fathers' tenure. A greater number of large male cohorts leave their natal pride than expected from their competitive ability and males rarely show an interest in mating until they enter a new pride. Larger male coalitions are more likely than small ones to gain residence in a pride adjacent to their natal pride, and also gain their first pride at a younger age. However, not all large cohorts are so successful because most cohorts of 6-8 males permanently split up soon after emigrating from their natal pride. About half of the secondary dispersal shown by resident adult coalitions is voluntary. Such voluntary secondary movements occur in three contexts: the coalition (1) annexes an additional pride thereby gaining access to more females (2) abandons one of several simultaneously held prides to spend more time with prides in which their cubs are younger and hence more vulnerable to infanticide (3) abandons one pride for another pride. In the third case males only abandon small cubs when going to much larger numbers of females, but they may abandon more females for fewer when their daughters are reaching maturity in the former pride. Males rarely reside in prides once their daughters have matured, and rarely return to breed in their natal pride. Compared to the large Serengeti population, the small isolated Ngorongoro population has lower levels of dispersal, higher levels of homozygosity and some deleterious effects of inbreeding.

Activity rhythm and the ranging of a solitary male mountain gorilla (Gorilla gorilla beringei)

To clarify the advantages of solitary life in gorilla males, a lone silverback mountain gorilla (Gorilla gorilla beringei) was studied for nine months in the natural habitat of the Virunga volcanoes. While the time budget for each activity and daily activity cycle were similar to those of groups, his daily journey distance and ranging patterns differed from those of groups. His movements were little influenced by the distribution and abundance of foods, which strongly influence the movements of groups. He notably increased his day journey distances when he encountered neighboring groups. He persistently followed the groups for days and went out of his usual range area. These encounters shifted his monthly range from his natal group's range to that of other groups. When the silverbacks of the encountered groups noticed his presence, they usually gave hoots and chest-beats and sometimes fought violently with him, while females and immatures did not show positive responses towards him. Lone males could have more chance to contact females and to lure them away from their groups than silverbacks within groups. The lone male stage, accompanied by frequent contacts with different groups, probably provides maturing males with useful knowledge of neighboring groups and areas.