Space and Habitat Use by a Red Wolf Pack and Their Pups During Pup-Rearing

ABSTRACT During summer 2005, we evaluated space and habitat use by red wolves (Canis rufus) during pup-rearing. Home-range sizes for red wolves (3 ad, 3 juv, and 4 pups) varied from 3.48 km² to 12.24 km². Red wolves selected agricultural fields over adjacent forested areas and used less space during pup-rearing than we expected based on prior knowledge of the species. Attending pack members rarely left pups alone, pack members shared pup-rearing duties, and male red wolves appeared to play a significant role in pup-rearing.     

ATYPICAL PUP REARING STRATEGIES BY SEA OTTERS

Eight tagged sea otter (Enhydra lutris) pups in central Prince William Sound, Alaska, weighed 6–15 kg at the time of separation from their mother. Four pups weighing 15 kg were able to forage successfully on their own. Three pups weighing ≤9 kg had negligible chances of survival and apparently were abandoned by sick females. Abandonment of a pup may reduce the burden on a sick female, enabling recovery and subsequent reproduction. One of the three sick females that abandoned a pup in this study recovered and pupped again. Abandonment of pups should occur most often in populations where females are stressed by poor food resources. Reassociation with a previous offspring, as observed once in this study, also may occur most frequently in food-limited populations where reproductive failures are most common and pup survivorship is significantly increased by additional maternal assistance.     

Dog Pups’ Attractiveness to Humans Peaks at Weaning Age

The domestic dog (Canis lupus familiaris) is characterized by greatly reduced parenting investment compared with the wild type wolf (C. l. lupus) from which it is descended. Unlike wolf pups, which are reared by both parents into their second year of life, dog pups are abandoned by their mother at weaning around eight weeks of age. This relatively small parental involvement may contribute to the high pup mortality observed in dogs not living as pets. We hypothesized that people would find dog pups most attractive around weaning age when conspecific parental care is significantly reduced and pup mortality rate is high. Younger and older pups would benefit less from human intervention because in the former case the mother is providing care, and in the latter their survival is already compromised. To test this hypothesis, 51 participants rated the attractiveness of 39 black and white headshot photographs presented on a computer screen of dog pups from three breeds (Jack Russell Terrier, Cane Corso, and White Shepherd), from birth to 7 months old. In line with our hypothesis, attractiveness of Cane Corsos peaked at 6.3 weeks of age; Jack Russell Terriers’ attractiveness peaked at 7.7 weeks; and White Shepherds were most attractive at 8.3 weeks. There were also differences in attractiveness between the breeds, with Cane Corsos rated less attractive than the other two breeds. If this attractiveness motivates humans to care for the dog pups and thereby improves pup survival, this could confer significant advantages to dogs, and may contribute to our understanding of the process of domestication.     

Territoriality of Feral Pigs in a Highly Persecuted Population on Fort Benning,Georgia

ABSTRACT We examined home range behavior of female feral pigs (Sus scrofa) in a heavily hunted population on Fort Benning Military Reservation in west-central Georgia, USA. We used Global Positioning System location data from 24 individuals representing 18 sounders (i.e., F social groups) combined with mark-recapture and camera-trap data to evaluate evidence of territorial behavior at the individual and sounder levels. Through a manipulative experiment, we examined evidence for an inverse relationship between population density and home range size that would be expected for territorial animals. Pigs from the same sounder had extensive home range overlap and did not have exclusive core areas. Sounders had nearly exclusive home ranges and had completely exclusive core areas, suggesting that female feral pigs on Fort Benning were territorial at the sounder level but not at the individual level. Lethal removal maintained stable densities of pigs in our treatment area, whereas density increased in our control area; territory size in the 2 areas was weakly and inversely related to density of pigs. Territorial behavior in feral pigs could influence population density by limiting access to reproductive space. Removal strategies that 1) match distribution of removal efforts to distribution of territories, 2) remove entire sounders instead of individuals, and 3) focus efforts where high-quality food resources strongly influence territorial behaviors may be best for long-term control of feral pigs.     

Abundance of Coffee berry borer in feral,abandoned and managed coffee on Hawaii Island

Coffee berry borer (Hypothenemus hampei Ferrari), the most damaging insect pest of coffee worldwide, was first detected on Hawaii Island in 2010. Poorly managed, abandoned and feral coffee sites on the island have since been thought to harbour coffee berry borer (CBB) populations, which then negatively impact neighbouring coffee farms. In the present study, we sought to quantify CBB abundance in these sites, which vary in management intensity and vegetation structure and diversity. We collected data on trap catch as a measure of CBB flight activity, fruit production and fruit infestation by CBB in eight well-managed farms and sites that were either poorly managed, abandoned or feral (wild) coffee. Sites were sampled bi-weekly over a period of 2 years from 2016 to 2017. We found that CBB flight activity was significantly higher in poorly managed sites relative to abandoned and feral sites, but was not significantly different from well-managed sites. Coffee production in well-managed farms was significantly higher than in abandoned and feral sites, but was not significantly different from poorly managed farms. CBB infestation in poorly managed sites was significantly higher than that observed in well-managed, abandoned and feral sites. We estimated an average load of 11–25 CBB per branch at poorly managed sites, compared to 3–9 per branch at well-managed sites, 1–16 per branch at abandoned sites and 1–3 per branch at feral sites. Our findings suggest that poorly managed sites should be prioritized for implementation of CBB control measures as part of a landscape-level integrated pest management (IPM) programme.     

Ecological Interactions Involving Feral Horses and Predators: Review with Implications for Biodiversity Conservation

For many ecosystems, feral horses are increasingly becoming an important if not dominant component of ungulate biomass and hence influence on community dynamics. Yet we still know little of how horses contribute to key ecological interactions including predator-prey and indirect competitive relationships at a community level. Notably, feral species like horses can exhibit life-history traits that differ from that of native (mainly artiodactyl) herbivore competitors. Artificial selection for traits like increased, early, or extended reproduction that have yet to be reversed by natural selection, coupled with naturally selected differences in anatomy and behavior, in addition to unique management objectives for horses compared to other species, means that the dynamics of feral horse populations are not likely to align with what might be expected of other large herbivores. Unexpected population dynamics and inherent biological asymmetries between native ungulates and feral horses may therefore influence the former via direct competition for shared resources and through enemy-mediated interactions like apparent competition. In several localities feral horses now co-exist with multiple native prey species, some of which are in decline or are species at risk. Compounding risks to native species from direct or indirect competitive exclusion by horses is the unique nature and socio-political context of feral horse management, which tends towards allowing horse populations to be limited largely by natural, density-dependent factors. We summarize the inherent asymmetries between feral horse biology and that of other ungulate prey species with consequences for conservation, focusing on predator-prey and emerging indirect interactions in multi-prey systems, and highlight future directions to address key knowledge gaps in our understanding of how feral horses may now be contributing to the (re)structuring of food webs. Observations of patterns of rapid growth and decline, and associated skews in sex ratios of feral horse populations, indicate a heightened potential for indirect interactions among large ungulate prey species, where there is a prevalence of feral horses as preferred prey, particularly where native prey are declining. In places like western North America, we expect predator-prey interactions involving feral horses to become an increasingly important factor in the conservation of wildlife. This applies not only to economically or culturally important game species but also at-risk species, both predators (e.g., wolves [Canis lupus], grizzly bears [Ursus arctos]) and prey (e.g., woodland caribou [Rangifer tarandus caribou]), necessitating an ecological understanding of the role of horses in natural environments that goes beyond that of population control. © 2021 The Wildlife Society.     

Plasticity of diel patterns in the diet and habitat use of feral, non-native fathead minnow Pimephales promelas (Actinopterygii, Cyprinidae) in a pond-dwelling population in England

The aim of the study was to test for diel patterns in the diet and habitat use in a feral, pond-dwelling, non-native fathead minnow Pimephales promelas population in England. Fish were collected in June 2009 using traps set in four habitat types (open waters, rushes??Juncus effusus, weeds??Potamogeton natans and mixed vegetation), then sexed and measured for total length and eviscerated weight in the laboratory. Data were analysed at 6-h intervals, with Fulton??s condition index and three dietary parameters (frequency of occurrence, number and weight) calculated. Minor diurnal differences in habitat use were observed in males, females and immatures, and these may be due to predator avoidance. Body condition varied greatly in rushes during daytime, probably due to shifts in habitat suitability (e.g. food, refuge). Detritus dominates the diet of native fathead minnow; however, planktonic crustaceans were the most important food resource for this population, with a clear ontogenetic shift, irrespective of habitat, towards greater proportion of ingested detritus in larger individuals. Overall, the results demonstrate that feral fathead minnows display substantial trophic plasticity and a wide range of habitat use, which is normally associated with invasive species. However, established fathead minnow populations in Europe are rare despite its wide-spread ornamental and scientific use.     

Determinants of reproductive success in voles: space use in relation to food and litter size manipulation

Spacing behaviour of female mammals is suggested to depend on the distribution and abundance of food. In addition, food limitation has been found to constrain the reproductive success of females. However, whether females maximize their reproductive success by adjusting space use in relation to current food availability and reproductive effort (e.g. litter size) has not been experimentally studied. We examined these questions by manipulating simultaneously food resources (control vs. food supplementation) and litter sizes (control vs. plus two pups) of territorial female bank voles (Clethrionomys glareolus) in large outdoor enclosures. Females with supplementary food had smaller home ranges (foraging area) and home range overlaps than control females, whereas litter size manipulation had no effect on space use. In contrast, the size of territory (exclusive area) was not affected by food supplementation or litter size manipulation. As we have previously shown elsewhere, extra food increases the reproductive success of bank vole females in terms of size and proportion of weaned offspring. According to the present data, greater overlap of female home ranges had a negative effect on reproductive success of females, particularly on survival of offspring. We conclude that higher food availability increases the reproductive success of bank vole females, and this effect may be mediated through lower vulnerability of offspring to direct killing and/or detrimental effects from other females in the population. Moreover, it seems that when density of conspecifics is controlled for, home range sizes of females, but not territoriality, is related to food resources in Clethrionomys voles.     

Dynamics of a small re-introduced population of wild dogs over 25 years: Allee effects and the implications of sociality for endangered species’ recovery

We analysed 25 years (1980–2004) of demographic data on a small re-introduced population of endangered African wild dogs (Lycaon pictus) in Hluhluwe-iMfolozi Park (HiP), South Africa, to describe population and pack dynamics. As small populations of cooperative breeders may be particularly prone to Allee effects, this extensive data set was used to test the prediction that, if Allee effects occur, aspects of reproductive success, individual survival and population growth should increase with pack and population size. The results suggest that behavioural aspects of wild dogs rather than ecological factors (i.e. competitors, prey and rainfall) primarily have been limiting the HiP wild dog population, particularly a low probability of finding suitable mates upon dispersal at low pack number (i.e. a mate-finding Allee effect). Wild dogs in HiP were not subject to component Allee effects at the pack level, most likely due to low interspecific competition and high prey availability. This suggests that aspects of the environment can mediate the strength of Allee effects. There was also no demographic Allee effect in the HiP wild dog population, as the population growth rate was significantly negatively related to population size, despite no apparent ecological resource limitation. Such negative density dependence at low numbers indicates that behavioural studies of the causal mechanisms potentially generating Allee effects in small populations can provide a key to understanding their dynamics. This study demonstrates how aspects of a species’ social behaviour can influence the vulnerability of small populations to extinction and illustrates the profound implications of sociality for endangered species’ recovery. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Wetland use by brood‐rearing female ducks in a boreal forest landscape: the importance of food and habitat

Habitat use by birds may be related to single or interacting effects of habitat characteristics, food resources and predators, but little is known about factors affecting habitat use by wetland species in boreal ecosystems. We surveyed brood‐rearing females and ducklings of four common boreal duck species to assess the effects of habitat structure and food resources on the use of wetlands by brood‐rearing ducks. Although wetland use by duck broods was related to habitat structure and food abundance, their relative importance varied among duck species. For the Common Goldeneye Bucephala clangula, a diving duck, aquatic invertebrates and large emerging insects were the most important factors associated with wetland use. Common Teal Anas crecca broods were observed more often on wetlands with greater Dipteran emergence, whereas in Mallard Anas platyrhynchos both habitat structure and large emerging insects were important. The occurrence of Eurasian Wigeon Anas penelope broods was related to emerging Diptera and habitat structure but the associations were not strong. The varying habitat and food requirements of common duck species could influence the success of wetland management programmes, and consideration of these factors may be particularly important for initiatives aimed at harvested species or species of conservation concern.     

Numbers, Turnover, and Social Structure of the Isle Royale Wolf Population

Observations of wolves on Isle Royale are reported for 1961–66,with interpretations including the earlier 3-year period describedby Mech (1966). On this 210-square-mile island the fully protectedwolf population varied from approximately 22 to 28 in midwinter.The major and minor foods were moose and beaver, respectively. The main pack varied in number between 11 and 22 with aboutthree breeding pairs believed present. The population remainedrelatively stable; mating occurred every winter; and adult mortalityappeared to be low. High mortality among pups seemed to be thepoint of population control. Socio-economic factors may havecontrolled the size of the large pack. Availability of foodduring the period of parturition and rearing probably was criticalto survival of young. Recruitment of young appeared to take place in years of highproduction of moose calves. Numbers in the large pack probablywere curtailed through the progressive exclusion of aged andsocially subordinate individuals. Under harassment these animalsseparated and became pack-following scavengers, then probablytrue loners ranging outside the area used by the pack. Smalleraggregations of two or three non-breeders were seen each winter,as were the loners, some of which appeared thin and weak. The only known breeding outside the big pack was in a groupof five present in the winter of 1965. This group was probablya family unit which separated from the main pack. A year laterthe male had disappeared, and remains of a pup, probably theirs,were found. In the winter of 1966 the alpha male of the largepack became lame and apparently was killed. This backgroundappears favorable for further changes in social organization.     

Birth and simultaneous rearing of two litters in a pack of captive African wild dogs (Lycaon pictus)

Two female African wild dogs (Lycaon pictus) in a pack of 10 animals at the Bronx Zoo gave birth to litters of nine and seven pups within a 2‐day period. Two pups from the litter of seven died before they were 2 weeks old, but the other 14 survived past weaning. Litter size, sex ratio, and pup developmental stages were all consistent with data obtained from other captive‐ and wild‐born litters. Both dams were very attentive to their litters, and during the pups' first 2 weeks spent >90% of their time in the dens with the pups. By 2 days after birth and during their first 2 weeks of life, the pups spent 86% of their time in a nursing position. Before parturition and during the first week post‐partum, one of the dams (DAL) was clearly dominant to the other (WHI). However, the females' dominance rank reversed 2 weeks post‐partum. On two occasions during the pups' first 2 weeks DAL stole and reared one of WHI's pups, but between Weeks 3 and 4 all of DAL's pups were stolen and WHI raised both litters as one until they were weaned. The pups began spending time out of their den at approximately 1 month of age. The timing of the births, the design of the wild dogs' management facility, and the presence of several dens in different enclosures within the facility all likely contributed to the successful rearing of the litters. The pups in both litters were very similar in size because of the short interval between births, so one litter did not have a competitive advantage over the other with respect to gaining access to the dam for milk. The facility's design helped mitigate aggression within the pack, and the presence of multiple dens enabled to dams to move the pups to different den sites and allowed the two females to stay visually and spatially apart from each other while remaining with the pack. Zoo Biol 0:1–17, 2006. © 2006 Wiley‐Liss, Inc.     

Domestic dogs as an edge effect in the Brasília National Park, Brazil: interactions with native mammals

Edge effects are a well-known result of habitat fragmentation. However, little has been published on fragmentation, isolation and the intrusive influence from the surrounding matrix at the landscape level. The objectives of the present study are to evaluate the presence of dogs in the Brasília National Park (BNP) in relation to habitat type and the influence from the surrounding matrix. In addition, this study examines the response of the native mammal fauna to the presence of dogs. Track stations were built along dirt roads in the BNP and subsequently examined for the presence or absence of tracks. We used a stepwise logistic regression to model the occurrence of five mammal species relative to habitat variables, with an α =0.05 to determine whether to enter and retain a variable in the model. A simulation of each species occurrence probability was conducted using a combination of selected habitat variables in a resource selection probability function. Results indicate a negative relationship between distance from the BNP edge and the probability of dog occurrences. From an ecological perspective, the presence of dogs inside the BNP indicates an edge effect. The occurrence of the maned wolf was positively associated with distance from a garbage dump site and negatively associated with the presence of dog tracks. The maned wolf and giant anteater seem to avoid areas near the garbage dump as well as areas with dog tracks. There is no support for the possible existence of a feral dog population inside the BNP, but the effects of free-ranging dogs on the wildlife population in such an isolated protected area must not be neglected. Domestic dog Canis familiaris populations and disease control programs should be established in the urban, sub-urban and rural areas surrounding the BNP, along with the complete removal of the garbage dump from the BNP surroundings.     

Dogs Canis familiaris as carnivores: their role and function in intraguild competition

• 1 Dogs Canis familiaris are the world's most common carnivore and are known to interact with wildlife as predators, prey, competitors, and disease reservoirs or vectors.
• 2 Despite these varied roles in the community, the interaction of dogs with sympatric wild carnivore species is poorly understood. We review how dogs have been classified in the literature, and illustrate how the location and ranging behaviour of dogs are important factors in predicting their interactions with wild prey and carnivores.
• 3 We detail evidence of dogs as intraguild competitors with sympatric carnivores in the context of exploitative, interference and apparent competition.
• 4 Dogs can have localized impacts on prey populations, but in general they are not exploitative competitors with carnivores. Rather, most dog populations are highly dependent on human‐derived food and gain a relatively small proportion of their diet from wild prey. However, because of human‐derived food subsidies, dogs can occur at high population densities and thus could potentially outcompete native carnivores, especially when prey is limited.
• 5 Dogs can be effective interference competitors, especially with medium‐sized and small carnivores. Dogs may fill the role of an interactive medium‐sized canid within the carnivore community, especially in areas where the native large carnivore community is depauperate.
• 6 Dogs can also be reservoirs of pathogens, because most populations around the world are free‐ranging and unvaccinated. Diseases such as rabies and canine distemper have resulted in severe population declines in several endangered carnivores coexisting with high‐density dog populations. Dogs can therefore be viewed as pathogen‐mediated apparent competitors, capable of facilitating large‐scale population declines in carnivores.
• 7 Based on this information, we propose conceptual models that use dog population size and ranging patterns to predict the potential for dogs to be intraguild competitors. We discuss how interactions between dogs and carnivores might influence native carnivore communities.

     

Ontogeny of social behaviour related to feeding in the Crab-eating fox (Cerdocyon thous) and the Bush dog (Speothos venaticus)

This study examines the development of social interactions involved in food apportionment in two captive parent-raised litters of Crab-eating foxes ( Cerdocyon thous ) and three of Bush dogs ( Speothos venaticus ), by presentation of live prey items and a regular food ration. Cerdocyon pups are initially very aggressive over food but, with experience, gradually develop the adult pattern of respecting ownership of food, without determining access by means of a dominance hierarchy. Adults mediate food transfers between pups and facilitate the learning process as well as the distribution of food resources.
Speothos pups never fight over or defend food and show no important ontogenetic changes in response to feeding situations.     

Development of a bait and baiting system for delivery of oral rabies vaccine to free-ranging African wild dogs (Lycaon pictus)

The objective of the study was to develop a bait and baiting system capable of delivering one effective dose of oral rabies vaccine to each member of a free-ranging African wild dog (Lycaon pictus) pack. Trials were conducted between June and October 2000. The results of cafeteria-style bait preference trials testing seven candidate baits in captive wild dogs revealed a significant preference for chicken heads (June trials: P = 0.023, September trials: P = 0.021). Trials using a topical biomarker (rhodamine B) showed that chicken head baits were sufficiently chewed on most occasions to rupture the vaccine container. Free-ranging wild dogs and young pups ingested chicken head baits. Significant dominance of bait intake by a single individual was seen in four of six study packs and in the three packs in which an alpha pair could be distinguished, the dominant feeder was an alpha animal. Pattern of bait distribution and degree of satiation had no effect on pack coverage (proportion of pack ingesting at least one bait). Pack coverage was significantly related to trial number (r = 0.71, P < 0.001), with pack coverage increasing with increased exposure of the pack to the baits. During 46 hr of diurnal observations of free-ranging wild dogs only two baits were lost to non-target species. A baiting system for the oral vaccination of captive and free-ranging wild dogs is proposed.     

Effects of food limitation,notonectid predation,and temperature on the population dynamics of Daphnia carinata

The relative contributions of invertebrate predation (Notonectidae: Anisops spp.), food limitation, and certain abiotic factors in driving the population dynamics of Daphnia carinata were studied for a two year period in a large farm dam in southern Victoria, Australia. Detailed measurements were made on the population densities of Daphnia and Anisops spp., the amount of food available, the nutritional status, and the size-specific fecundity of Daphnia. The density of the Daphnia population at the field site oscillated closely with water temperature. The amplitude of the population fluctuations varied seasonally, being much greater during the warmer months of the year and switching to fluctuations with low peaks when water temperature dropped below approximately 15°C. Anisops spp. densities were greatest in winter and declined during the spring of each year. Nymphs appeared in late spring and early summer and numerically dominated the population. During the warmer periods of the year, the daphnid population went through a series of rapid growth phases leading to over-exploitation of food resources and subsequent population collapses. Daphnia population densities were not correlated with Anisops numbers suggesting that predation was not a major regulatory factor during the warmer periods of the year. When water temperatures fell below ca. 15°C daphnid population densities remained low despite high food levels. During this period the impact of Anisops may have been greater. Two distinct phases were identified: a warm water period when food limitation was the main regulatory factor, and a cool water period when Anisops predation may have been the paramount factor. Low oxygen concentrations were associated with heavy rainfall in the spring and may have had a limiting effect on Daphnia for short periods. Daphnia may have had an important role in sustaining the Anisops population in the pond over each winter.     

Denning behaviour and activity of arctic fox Alopex lagopus pups: Implications of food availability

Summary The behaviour of arctic fox Alopex lagopus pups was studied in 51 in two regions of southern Scandinavia (60 and 63°N) and in 51 on the western coast of Svalbard (79°N). In Scandinavia, observations were made both in years of high and low abundance of food (i.e. voles and lemmings). No rodents live on the western coast of Svalbard, where foxes depend mainly on sea birds. Pups were on average lying nearly half the time, with explore and play fight next in frequency. Pups in a year of decreasing or low lemming abundance rested more outside the den, rested more overall, and less frequently indulged in exploration or play fighting than pups in years of higher abundance of voles and lemmings. They also began following adults at an early age and abandoned their natal den earlier. Svalbard pups were intermediate in several respects, but they regularly abandoned their natal den at the age of about 1 1/2 months. Pups at dens were active 24% of daytime hours (08.00–20.00) and 31% of nighttime hours (20.00–08.00).     

Survival,Fecundity, and Movements of Free-Roaming Cats

Abstract: Free -roaming cats (e.g., owned, semi-feral, and feral) impact wildlife worldwide through predation, competition, and disease transmission. Baseline ecological information necessary for population management is lacking. We radiocollared free-roaming cats (feral, n = 30; semi-feral, n = 14; owned, n = 10) in Caldwell, Texas, USA between October 2004 and November 2005 and compared population demographics among sex and ownership classification. We found ranges and movements declined across ownership classes whereas survival and fecundity increased. Our findings suggest that human interactions (e.g., feeding) may result in high, localized free-roaming cat densities, which may concentrate feral cat impacts and should be considered when evaluating population control strategies.     

Seed production and seed predation in a patchy and time-varying environment. Dynamics of a milkweed — tephritid fly system

Summary Vincetoxicum hirundinaria is a longlived perennial herb. Its pod production was measured during seven years in about 40 small isolated patches in two study areas in southeastern Sweden. Total pod production in the two areas varied synchronously and up to about 200 times between years. This variation was mainly due to drought conditions as determined by the interplay of weather (sunshine h) and site characteristics.Populations of a univoltine tephritid fly, euphranta connexa, whose larva feeds on V. hirundinaria seeds in the maturing pods, were monitored for five and seven years in the two study areas respectively. Larval fly populations in the two areas varied 30 and 50-fold between years, with highs in years when pods were abundant and lows when pods were scarce. The percentage of pods attacked by E. connexa, however, varied in the opposite direction, with very high attack rates (about 100%) when pods were scarce and low rates (down to 10–20%) when pods were common. Thus the temporal tracking of food resources by E. connexa was poor, resulting in yearly variations in the amount of unattacked pods (and seeds) being about 2,00-fold.Many host plant patches were small and totally without pods in some years, causing frequent local extinctions of E. connexa. Patches were, however, readily colonized in later years when pods appeared again. Low overall attack rates in certain years were thus only to a minor extent explainable by host plant patches being uncolonized by the fly. The efficient spatial tracking of resources by the fly population allows this population system to be analyzed largely in terms of its temporal dynamics.Although E. connexa populations often exploit only a minor part of their potential larval resources, the rate of population change was closely correlated with these resources expressed on a per capita basis. Natural enemies only have negligible effects on E. connexa population trends. In this population system the herbivore (seed predator) population is thus controlled by its food resources, but weather-imposed temporal variations in resource set are too large for the herbivore population to closely track its resource base. This temporal tracking inertia has important implications for the long-term production of healthy seeds.