Territorial Sites Research Articles

On the cue for male territorial site selection in the dragonfly,Nannophya pygmaea: A field experiment

A field observation of the dragonflyNannophya pygmaea revealed that males prefer some territorial sites to others, and that these same sites attract more females than others (Tsubaki & Ono, 1986, 1987). In this paper, we asked if males choose territorial sites in response to female dispersion or distribution of resources. We conducted 3 types of removal experiments to test the following 2 hypotheses; (1) a male may assess the territory quality by the female encounter rate at his site (learning), (2) a male may assess the resource quality (or quantity) in the territory. The results of our experiments show that males discriminate attractive and less attractive territorial sites without any mating experience within the study area. Moreover, the territorial site preference of males was not affected by the mating experience. Therefore, males probably choose territorial sites by resource quality rather than by female dispersion.

Variations in courtship activity among male blue grouse: do some males breed more than others?

We developed a primary feather wear index (WI) for blue grouse (Dendragapus obscurus) to examine variations in courtship activity among males. Three percent of 276 yearling males, and less than 1% of 144 yearling and adult females examined throughout spring and summer showed evidence of such wear. Among 630 adult males, 48% exhibited "courtship wear." Mean courtship wear among males 2 years old and older increased steadily throughout the spring and summer, generally paralleling what would be predicted from cumulative reproductive activity. However, there was much variation among males, ranging from no wear to heavy wear, even by late summer. These data are consistent with earlier suggestions that breeding may be skewed among male blue grouse, as in lek-breeding tetraonines. Limited samples indicate that primary feather wear was not related to the age of males (more than 1 year old) or their occupancy of persistent or transient territorial sites.

EXPERIMENTS ON THE LIMITATION OF BIRD NUMBERS BY TERRITORIAL BEHAVIOUR

Summary(1) This paper examines removal and other experimental studies on the role of territorial behaviour in the limitation of bird densities. Experimental design is discussed, as are the types of conclusions that can be drawn.(2) Experiments have been conducted on more than 40 species from a wide range of taxonomic groups. Most provided evidence for density limitation, probably mediated by territorial behaviour, and for the existence of a non‐territorial sector able to take territories when territory owners were removed or when additional habitat was made available. Experiments in the breeding season indicated that some surplus birds, although younger on average then territorial birds, were sexually mature and able to breed when given the chance. In some species, replacement birds bred less well than other territorial birds, but in other species no difference was apparent between the two groups.(3) Other experiments indicated that, while density was limited by territorial behaviour in good habitats, this was not the case in poor habitats, and that some individuals would move from poor to good habitat when territory owners were removed from good habitat.(4) In some species, non‐territorial birds of breeding age were present in the population despite the existence of vacant territorial sites, while in others replacements were observed on good territories but not on poor ones. The implications were that site quality influenced whether settlement, defence and breeding occurred, and that some individuals had more stringent site requirements than others. In some seabirds' sites in the centre of a colony were more attractive than sites on the edges.(5) Many land‐bird species that have been studied show two peaks of territorial activity each year, in autumn and in spring, and a limitation on breeding density can occur at either or both seasons, depending on conditions.(6) The fact that densities of many bird species fluctuate greatly from year to year is not inconsistent with the limitation of density by territorial behaviour. Several mechanisms are apparent through which density might be limited by territorialism at different levels in different years, so that surplus non‐territorial birds are present in years of low territorial density, as well as in years of high territorial density.(7) Experiments have shown that density is limited by the presence of territorial birds, in some species at different levels in different areas or years. The next step is to find whether density is regulated by the presence of territorial birds over a period of years in a density‐dependent manner. For this, observational data are required to find whether the proportion of birds that is excluded by territorial behaviour each year varies with the total number available for settlement. Such studies can be made only on species in which non‐territorial birds can be counted accurately, as well as territorial ones.

Alternative mating tactics in male white-faced dragonflies (Leucorrhinia intacta): plasticity of tactical options and consequences for reproductive success

Alternative tactics used by males to obtain mates usually are associated with genetic and/or phenotypic differences between the behavioral morphs. This system of white-faced dragonfly (Leucorrhinia intacta) alternatives is characterized by plasticity of tactical options for individual males. Males may act either as territorials, and defend small perch-centered territories on the study pond, or they act as transients, spending most of their time in vegetation surrounding the pond and sallying out at intervals in search of mates. The two tactics remain in constant proportions over a broad range of densities, so transients do not result only from a ‘filling in’ of suitable territorial sites. Males adopt tactics independently from day to day, with no significant influences of phenotypic variation, priority of arrival at the breeding site, or prior success in a role. We interpret this system as based on conditional, frequency-dependent choice of alternatives by a population of males not differing significantly in their abilities to employ one tactic or the other, but we cannot exclude entirely the possibility of mixed strategies. Average daily mating success is equal for territorial and transient males, supporting predictions of mixed and conditional ESS hypotheses. Males of each tactic obtain matings daily in proportion to their representation in the population for most data samples. Deviations from the expected mating success provide no information of use in selecting one or the other tactic on subsequent days. We suggest this system of alternatives represents a conditional mating strategy, in which males adopt tactics based on the availability of perches relative to oviposition substrate and on interactions within and between tactics that are influenced by the relative frequencies of territorial and transient males.

Reproductive behavior of the dragonfly,Orthetrum japonicum (Odonata: Libellulidae)

The reproductive behavior of the dragonfly,Orthetrum japonicum, is described. Behavioral processes of turnover of territorial males, simultaneous guarding of 2 females by a male, and copulation by non-territorial males are described. The males with longer hind wings won the territorial conflicts more frequently. The total duration of territorial residence of a given male was correlated with the number of his matings, but not correlated with the length of his abdomen or hind wings. The territorial site with the lower degree of vegetation cover was occupied by males more consistently. Males in more consistently occupied territorial sites did not have longer abdomen and hind wings than males in less consistently occupied sites. The territorial site where the larger number of copulations was observed was not occupied more consistently. Selection episode analysis using the method of Arnold & Wade (1984a, b) showed that direct selection on the hind wing length favored the short wing and that direct selection on the abdomen length favored the long abdomen during mating.

Pyramiding Behavior in the Inca Dove: Adaptive Aspects of Day-Night Differences

ENG, R. L. 1963. Observations on the breeding biology of male Sage Grouse. J. Wildl. Manage. 27: 841-846. HANNON, S. J., B. R. SIMARD, F. C. ZWICKEL, AND J. F. BENDELL. 1979. Differences in the gonadal cycles of adult and yearling Blue Grouse. Can. J. Zool. 57:1283-1289. JAMIESON, I. G. 1985. Behavior of yearling male Blue Grouse and its relation to delayed breeding. Wilson Bull. 97:71-77. JAMIESON, I. G., AND F. C. ZWICKEL. 1983. Spatial patterns of yearling male Blue Grouse and their relation to recruitment into the breeding population. Auk 100:653-657. LEWIS, R. A. 1981. Characteristics of persistent and transient territorial sites of male Blue Grouse. J. Wildl. Manage. 45:1048-1051. LEWIS, R.A. 1984a. Non-territorial adult males and breeding densities of Blue Grouse. Wilson Bull. 96:723-725. LEWIS, R. A. 1984b. Survival, behavior, use of territories, and breeding densities of male Blue Grouse in coastal British Columbia. Ph.D.diss., Univ. Alberta, Edmonton. LEWIS, R. A. 1985. Use of space by territorial male Blue Grouse. Wilson Bull. 97:97-101. LEWIS, R. A., AND F. C. ZWICKEL. 1980. Removal and replacement of male Blue Grouse on persistent and transient territorial sites. Can. J. Zool. 58:1417-1423. LEWIS, R. A., AND F. C. ZWICKEL. 1981. Differential use of territorial sites by male Blue Grouse. Condor 83:171-176. LEWIS, R. A., AND F. C. ZWICKEL. 1982. Survival and delayed breeding in male Blue Grouse. Can. J. Zool. 60:1881-1884. McNICHOLL, M. K. 1978. Behaviour and social orga ization in a population of Blue Grouse on Vancouver Island. Ph.D.diss., Univ. Alberta, Edmonton.

Aggressiveness, incidence of singing, and territory quality of male blue grouse

The relative aggressiveness and proportion of time spent singing (incidence of singing) were assessed for male blue grouse (Dendragapus obscurus) occupying high- and low-quality territorial sites. Playback experiments were used to assess the relative aggressiveness of males; no support was obtained for the hypothesis that males on high-quality sites are more aggressive than those on low-quality sites. Prior experience with an area may be more important than aggressiveness in determining the quality of territorial site that is obtained. In 1 of 2 years, males on high-quality sites were observed hooting (singing) a greater proportion of the time than were males on poorer sites. A greater incidence of hooting by males on high-quality sites may be one factor that results in more females being observed near these males than near males on less suitable areas, as was found in a previous study.

Competition for Territorial Sites and Alternative Mating Tactics in the Dragonfly, Nannophya Pygmaea Rambur (Odonata: Libellulidae)

1. Male Nannophya pygmaea defend small territories on or near small bodies of water. Sexually receptive females arrive at these sites to oviposit, and are usually intercepted by these territorial males. 2. Not all males are territorial however, some try to 'sneak' copulations with females attracted to established territories. 3. Males are both residents and at some stage of their life. 4. Number of increase at an accelerating rate with male density at the reproductive area. 5. Some territorial sites are occupied more consistently than others, and there is considerable turnover in territory ownership at some sites during the course of the reproductive season. 6. Some changes in ownership occur because an intruder defeats the resident in an aerial contest. 7. Highly contended territorial sites attract more females than others, and daily mating frequency is highest in males occupying these territories. 8. However, sneakers appear to be as successful in gaining copulations as males who occupy less contended territories.

Consistency in the relative attractiveness of a set of landmark territorial sites to two generations of male tarantula hawk wasps (Hymenoptera: Pompilidae)

Males of the tarantula hawk wasp Hemipepsis ustulata defend conspicuous palo verde trees on mountain ridges. A comparison of data from two flight seasons (1981 and 1980) reveals that the preference rankings of males for a set of perennial territories on one ridge remained highly consistent from generation to generation. This is the first thoroughly documented demonstration for insects that landmarks used as mating encounter sites retain the same relative attractiveness from year to year. The stability of male preferences is indirect evidence that access to females is related to the ability to acquire high-ranking territories. Moreover, in both years, (1) the flight season was 2.5 to 3 months long, (2) the range of body sizes in this highly variable species remained the same, and (3) the ratio of territorial males to non-territorial patrollers was constant. A key difference was a strong reduction in the total number and density of males found in the study site in 1981. The wasps responded to the decrease in competition for perch territories by failing to occupy some low-ranking sites that were taken in 1980.

Persistence of cartilage proteoglycan and link protein during matrix-induced endochondral bone development: An immunofluorescent study

Monospecific antibodies to cartilage proteoglycan monomer and link protein were employed with immunofluorescence microscopy to determine the tissue distribution of these constituents during matrix-induced endochondral bone development. Subcutaneous implantation of demineralized diaphyseal bone matrix resulted in new endochondral bone formation. On Day 3, the implant consisted of mesenchymal tissue which did not contain any demonstrable cartilage-related proteoglycan or link protein. With the onset of early chondrogenesis on Day 5, cartilage proteoglycan monomer and link protein were first localized together in the cartilage matrix, particularly around chondrocytes in territorial sites. Progressively more staining around cells was observed at Days 7 and 9. On Day 9, when mineralization was first observed, there was no evidence of a net loss of these molecules prior to mineralization of the cartilage matrix. On Day 11 and thereafter, bone formation was observed by appositional growth on calcified cartilage spicules. Whereas the osteoblasts and bone matrix were devoid of any staining for cartilage proteoglycan and link components, the residual, partly mineralized cartilage spicules still reacted with antibodies to cartilage proteoglycan monomer and link protein in territorial sites, but in reduced amounts, indicating a loss of these molecules associated with a loss of hypertrophic chondrocytes. Since mineral prevented the access of Fab' antibody subunits, demineralization after fixation was routinely employed. The results reveal that cartilage proteoglycan monomer and link protein are present around chondrocytes in hyaline cartilage during the early stages of endochondral bone formation and that there is no net loss of these molecules prior to mineralization of this cartilage matrix as was previously thought.

Characteristics of Persistent and Transient Territorial Sites of Male Blue Grouse

Male blue grouse (Dendragapus obscurus) are promiscuous and territorial, with territories serving as areas where males can display and breed without interference from other males (Bendell and Elliott 1967). Intensive studies on Vancouver Island, British Columbia, demonstrated that areas used by males for territories had unequal frequencies of use (Lewis 1979). Some were used regularly, others intermittently. Sites used at least 9 of the 10 years studied (1969-78) were called persistent, those used 8 years or less (Lewis 1979). Although the term persistent implies use in every year, sites occupied for 9 years were included in this category because of the chance that the site actually was used in the year it was recorded as vacant, even though the presence of a male was undetected by the field techniques used. Experimental evidence indicates that males prefer persistent sites for territories (Lewis and Zwickel 1980), and males using these sites had significantly more females near them in early spring and survived significantly longer than those using transient sites (Lewis 1979). Here I examine physical and vegetative characteristics of a series of persistent and transient territorial sites to identify those features that may be important in their selection by blue grouse.

Differential Use of Territorial Sites by Male Blue Grouse

We examined the pattern of use of territorial sites occupied by male Blue Grouse on a 485-ha area over a 10-year period, 1969 to 1978. Some sites were occupied continuously while others were used only intermittently; these were called "persistent" and "transient" sites, respectively. Approximately one-half of the transient sites were vacant in any given year. Males on persistent sites survived significantly longer and had significantly more females near their territories during the breeding season than those on transient sites. Thus, males on persistent sites may have better opportunities for breeding than males on transient sites. These results help to explain why yearling males delay breeding, despite being physiologically able to do so, and they also provide new insights into how breeding densities of males are regulated.

Removal and replacement of male blue grouse on persistent and transient territorial sites

In the springs of 1978 and 1979 we removed all male blue grouse (Dendragapus obscurus), both original occupants and subsequent replacements, from a series of persistent and transient territorial sites (those used regularly and intermittently, respectively). In both years more replacements settled on persistent than on transient sites. Most replacement males were adults, most of which likely would not have taken territories had we not made these sites available. The presence of nonterritorial adults, reported here for the first time, suggests that territorial behaviour limits breeding densities of male blue grouse. Testes of replacement adults, although smaller than those of resident males collected at comparable times, all contained mature sperm. Yearling males are seldom territorial; but of eight that took territories on removal sites all except one selected persistent sites.