Variation In Territorial Behaviour Research Articles

Terrestrial invasive species alter marine vertebrate behaviour

Human-induced environmental changes, such as the introduction of invasive species, are driving declines in the movement of nutrients across ecosystems with negative consequences for ecosystem function. Declines in nutrient inputs could thus have knock-on effects at higher trophic levels and broader ecological scales, yet these interconnections remain relatively unknown. Here we show that a terrestrial invasive species (black rats, Rattus rattus) disrupts a nutrient pathway provided by seabirds, ultimately altering the territorial behaviour of coral reef fish. In a replicated ecosystem-scale natural experiment, we found that reef fish territories were larger and the time invested in aggression lower on reefs adjacent to rat-infested islands compared with rat-free islands. This response reflected changes in the economic defendability of lower-quality resources, with reef fish obtaining less nutritional gain per unit foraging effort adjacent to rat-infested islands with low seabird populations. These results provide a novel insight into how the disruption of nutrient flows by invasive species can affect variation in territorial behaviour. Rat eradication as a conservation strategy therefore has the potential to restore species interactions via territoriality, which can scale up to influence populations and communities at higher ecological levels.

Costs of territoriality: a review of hypotheses, meta-analysis, and field study.

The evolution of territoriality reflects the balance between the benefit and cost of monopolising a resource. While the benefit of territoriality is generally intuitive (improved access to resources), our understanding of its cost is less clear. This paper combines: 1. a review of hypotheses and meta-analytic benchmarking of costs across diverse taxa; and 2. a new empirical test of hypotheses using a longitudinal study of free-living male territorial lizards. The cost of territoriality was best described as a culmination of multiple factors, but especially costs resulting from the time required to maintain a territory (identified by the meta-analysis) or those exacerbated by a territory that is large in size (identified by the empirical test). The meta-analysis showed that physiological costs such as energetic expenditure or stress were largely negligible in impact on territory holders. Species that used territories to monopolise access to mates appeared to incur the greatest costs, whereas those defending food resources experienced the least. The single largest gap in our current understanding revealed by the literature review is the potential cost associated with increased predation. There is also a clear need for multiple costs to be evaluated concurrently in a single species. The empirical component of this study showcases a powerful analytical framework for evaluating a range of hypotheses using correlational data obtained in the field. More broadly, this paper highlights key factors that should be considered in any investigation that attempts to account for the evolutionary origin or ecological variation in territorial behaviour within and between species.

Territoriality and condition of chevron butterflyfish (Chaetodon trifascialis) with varying coral cover on the great barrier reef, Australia

The chevron butterflyfish, Chaetodon trifascialis, is among the most specialised coral-feeding fish, and while it is known to be very susceptible to extensive depletion of its preferred coral prey (tabular Acropora spp.), their specific responses to changing coral cover are poorly understood. The purpose of this study was to test for variation in territorial behaviour and condition of C. trifascialis relative to spatial variation in coral cover across four mid-shelf reefs on the Great Barrier Reef. Explicit consideration was also given to the territorial arrangement and interactions among sympatric individuals, with a view to better understanding the sociality of this species. Variation in overall coral cover (which ranged from 26.5-73.4% among sites) as well as cover of tabular Acropora (13.3-44.8%) had limited effect on the territoriality or body condition of C. trifascialis. Rather, individual variation in territoriality was attributable to differences in gender and size of fish. Male C. trifascialis were generally larger and also had larger territories than female counterparts. They also interacted with conspecifics (and congenerics) much more than females. Taken together, these results support previous assertions that C. trifascialis is haremic. There was, however, limited evidence of male territories encompassing the territories of >1 female. While the sociality of C. trifascialis is clearly atypical of Chaetodon butterflyfishes, more work is needed to understand their reproductive biology as well as their behavioural responses to changing coral cover.

When to defend? Optimal territoriality across the Numic homeland

Explanations for the complex human decisions that lead to territoriality have focused on models of economic defendability. While powerful, these models fail to explain variation in territorial behavior in all cases. To help overcome this limitation, here we offer an approach that synthesizes the logic of economic defendability with a general optimality model from behavioral ecology: the marginal value theorem (MVT). Through the MVT we add considerations of how resource profitability, in addition to abundance, alters the amount of time individuals should spend foraging in order to meet caloric requirements, and how far they should travel between foraging locations. Where and when individuals rely on abundant, but lower profitability resources, they should spend more time foraging and less time traveling, which leads to smaller territories that are easier to defend, and wherein each unit of land has a greater economic value per capita thereby increasing the benefits of economic boundary defense. Numic foragers of the Great Basin and surrounding areas provide an illustrative case study to validate this general ecological model. The results show that individuals exploiting high density but low profitability resources live in smaller territories and have higher rates of resource privatization, thereby explaining societal differences between Northern Paiute and Shoshone bands. Importantly, because defended resource patches are the target of women's foraging, the payoffs to territoriality are likely structured by women's risk averse foraging decisions. We suggest this model is capable of explaining variation in hunter-gatherer territoriality worldwide.

Geographical variation in male territory defence strategies in an avian ring species

Interactions between sexual selection and ecology can drive phenotypic divergence between populations. Geographical variation in female preferences has been linked to ecology in several studies, but much less is known about patterns of geographical variation in male competition. I asked whether male aggressive territorial behaviour varied among three breeding populations of a ring species, the greenish warbler, Phylloscopus trochiloides. I measured aggressive response to playbacks of conspecific song at multiple time points to determine how territorial behaviour varied throughout the breeding season both within and between populations. Differences in the abundance and timing of resources necessary for raising offspring can shape male competitive strategies, and competition may consequently vary as a function of resource availability. I therefore combined assays of temporal variation in aggressive behaviour with season-long measures of food abundance, population density and parental provisioning rates. I found that the populations differed in intensity of aggressive response, the seasonal pattern of territoriality and the traits used in territorial responses. Overall intensity of aggression was lowest but most prolonged in the population with the lowest food abundance and highest population density, and males responded to playback primarily by singing. By contrast, birds in the two populations that experienced high food abundance and low population density exhibited a burst of aggressive display behaviour only when females were fertile. The results suggest that territorial strategies vary geographically and respond to limited resources, switching in function from season-long food defence where food is scarce to mate guarding where mates are scarce. Interactions between sexual selection and ecology across large geographical scales may ultimately lead to population divergence. The geographical variation in territorial behaviour observed in the greenish warbler implies that male competition may be an important diversifying force in this system.

Integrating resource defence theory with a neural nonapeptide pathway to explain territory-based mating systems.

The ultimate-level factors that drive the evolution of mating systems have been well studied, but an evolutionarily conserved neural mechanism involved in shaping behaviour and social organization across species has remained elusive. Here, we review studies that have investigated the role of neural arginine vasopressin (AVP), vasotocin (AVT), and their receptor V1a in mediating variation in territorial behaviour. First, we discuss how aggression and territoriality are a function of population density in an inverted-U relationship according to resource defence theory, and how territoriality influences some mating systems. Next, we find that neural AVP, AVT, and V1a expression, especially in one particular neural circuit involving the lateral septum of the forebrain, are associated with territorial behaviour in males of diverse species, most likely due to their role in enhancing social cognition. Then we review studies that examined multiple species and find that neural AVP, AVT, and V1a expression is associated with territory size in mammals and fishes. Because territoriality plays an important role in shaping mating systems in many species, we present the idea that neural AVP, AVT, and V1a expression that is selected to mediate territory size may also influence the evolution of different mating systems. Future research that interprets proximate-level neuro-molecular mechanisms in the context of ultimate-level ecological theory may provide deep insight into the brain-behaviour relationships that underlie the diversity of social organization and mating systems seen across the animal kingdom.

Food availability affects strength of seasonal territorial behaviour in a cooperatively breeding bird

Seasonal patterns in territorial behaviour are common in many species, and are often attributed to the adaptive benefits of increased defence or the provision of information to potential competitors or mates during the breeding season. However, because defence behaviour is likely to be costly in terms of time and energy, an alternative possibility is that decreases in the nonbreeding season are a consequence of reduced food availability. We studied territoriality in the pied babbler, Turdoides bicolor, a cooperatively breeding bird species that defends permanent territories. Groups interacted with rivals less and responded less strongly to an experimentally simulated intrusion of neighbours in nonbreeding periods compared to the breeding season. Foraging efficiency and biomass intake were significantly lower in the nonbreeding season, which resulted in birds being significantly lighter at this time of year. Finally, a feeding experiment in the nonbreeding season showed that groups given supplementary food significantly increased their response to a simulated territorial intrusion. These results indicate that the reduction in territorial behaviour during the nonbreeding season may be attributed, at least in part, to a reduction in food availability. We suggest that future studies on seasonal variation in territorial behaviour, especially those investigating species in which two or more individuals combine their defence, should take this potential constraint into account.

Application of GIS to investigate the use of space in coral reef fish: a comparison of territorial behaviour in two Red Sea butterflyfishes

The space use of two coral‐feeding Red Sea butterflyfish species (Chaetodon austriacus and C. trifascialis) was studied at three sites in the Gulf of Aqaba to determine the extent of intraspecific territoriality. Individuals or pairs were observed in shallow water (<5 m). Their locations were recorded on maps of each study reef. The Animal Movement Analysis Extension (AMAE) in ArcView was used to plot territory borders and compute territory size for each species. Chaetodon austriacus, a generalist corallivore that exploited evenly distributed food resources, maintained small exclusive pair territories with clearly defined territory boundaries. In contrast, C. trifascialis, a specialist corallivore that exploited patchily distributed food resources, demonstrated considerable variation in territorial behaviour that ranged from the defence of small exclusive solitary territories to the shared use of a large home range. Comparisons of territory area estimates showed that 95% kernel probability density function territory boundaries matched intuitive territory boundaries and, unlike the minimum convex polygon area, did not contain obvious areas that were not used by individuals or pairs. We show that comparing different territory size measures can be very useful in describing subtle differences in territorial behaviour between species and studies. For this purpose, GIS is an ideal technology with which to carry out such analyses quickly and easily.

Does dewlap size predict male bite performance in Jamaican Anolis lizards?

Summary The theory of the evolution of secondary sexual traits through male–male competition is based on the assumption that these traits are reliable cues for an animal's fighting capacity. In this paper, we test whether a secondary sexual trait, dewlap size, is an honest predictor of bite strength in Anolis lizards. Since male anoles will bite one another during territorial fights, bite performance may play an important role in determining the outcome of male–male fights. We measured dewlap size and bite force in a size series of adult males of three Jamaican anoles, i.e. Anolis grahami Gray 1845, A. lineatopus Gray 1840 and A. valencienni Duméril &amp; Bibron 1837. In both A. grahami and A. lineatopus, males with relatively large dewlaps tend to bite relatively harder, while the relationship between relative dewlap size and bite force was clearly non‐significant within the twig anole A. valencienni. Our results thus suggest that dewlap size is an indicator of relative bite force in the former two species, but not in the latter. We argue that interspecific variation in territorial behaviour might explain this difference.

Territorial and foraging behaviour of two corallivorous butterflyfishes

The territorial and foraging behaviour of two Red Sea butterflyfish species was studied at three sites in the Gulf of Aqaba. Chaetodon austricaus, a generalist corallivore that exploited evenly distributed food resources, maintained exclusive pair territories. Individuals fed by grazing for brief periods on a coral colony before moving to the next. In contrast, C. trifascialis, a specialist corallivore that exploited patchily distributed food resources, demonstrated considerable variation in territorial behaviour that ranged from the defence of exclusive solitary territories, to the shared use of a large home range. Individuals showed highly variable feeding behaviour, from grazing analogous to C. austriacus, to continual use of a single large coral colony. The results of this study demonstrate how the use of space by individuals depends critically upon the distribution of key food resources. In addition, the results demonstrate that foraging behaviour of territorial butterflyfish can be quite plastic, and adapt to local conditions.

The Mexican Subspecies of Townsend's Solitaire in the Animas Mountains: A First for New Mexico and the United States

GAVIN, T. A., AND E. K. BOLLINGER. 1988. Reproductive correlates of breeding-site fidelity in Bobolinks (Dolichonyx oryzivorus). Ecology 69:96-103. GREENWOOD, P. J. 1980. Mating systems, philopatry and dispersal in birds and mammals. Animal Behavior 28:1140-1162. HUSAK, M. S. 1997. Seasonal variation in territorial behavior of the golden-fronted woodpecker (Melanerpes aurifrons). Unpublished M.S. thesis, Angelo State University, San Angelo, Texas. HUSAK, M. S. 2000. Seasonal variation in territorial behavior of the golden-fronted woodpecker in west-central Texas. Southwestern Naturalist 45:

Seasonal Variation in Territorial Behavior of Golden-Fronted Woodpeckers in West-Central Texas

Seasonal Variation in Territorial Behavior of Golden-Fronted Woodpeckers in West-Central Texas

Response to Intruders and the Dear Enemy Phenomenon in Female Tree Lizards, Urosaurus ornatus, in Relation to Age and Reproductive Condition

Response to Intruders and the Dear Enemy Phenomenon in Female Tree Lizards, Urosaurus ornatus, in Relation to Age and Reproductive Condition

Sexual and seasonal variation in territorial behaviour of kestrels, Falco tinnunculus

Territorial behaviour among male and female European kestrels was examined by simulating intrusions of conspecifics. An adult, caged decoy kestrel, male or female, was presented to wild birds. During late courtship as well as after the eggs hatched, resident males responded with overt aggression in contests with other males near the nest. Females showed less intense aggression in intra-sexual encounters shortly before laying commenced than before or after this period. After the eggs hatched, the intensity of female aggression in intra-sexual encounters was related to brood size. In inter-sexual encounters near the nest during early and late courtship, many females solicited the decoy male. In the non-breeding season, the intensity of territorial aggression increased, independently of sex and of age of the birds, from early autumn to late autumn/early winter and persisted at a high level throughout the winter.