The Condor 94:83-92 0 TheCooper Ornithological Society 1992

SETTLEMENT PERIOD AND FUNCTION OF LONG-TERM TERRITORY IN TROPICAL

GAETAN LEFEBVRE, BRIGITTE POULIN AND RAYMOND MCNEIL D@partementde sciencesbiologiques, Universitk de Montrkal, C.P. 6128, Succ. “A,‘ ” Montrkal, Qu&becH3C 3J7, Canada

Abstract. We studied the territorial behavior of four insectivorouspasserines residing in a tropical mangrove of northeastern . Data were obtained through mist-netting and direct observation of color-banded individuals, regularly scheduledover two complete annual cycles.Seasonal variation in food resources(arthropods) and the ’ diet also were evaluated. A chronologicalcluster analysiswas used to determine the settlement periods of territories, the former being illustrated by the probabilistic Jennrich-Turner method. Three of the four specieshold year-round territories. These long-term territories were settled only once a year, immediately after the breeding seasonwhen food was abundant. The territorial settlementwas synchronousamong all individuals ofa ,favoring strongmodifications of the territorial mosaic. Considering the absenceof territorial settlement prior to breeding and the high stability of territorial mosaics even during periods of low food abundance, territoriality during the non-breeding seasonprimarily appearsto ensurea breeding site for the next reproductive period. These resultscontrast with those from temperateregions where territoriality over the non-breeding seasonprimarily enhancesthe survival of individuals during periods of food shortage. Key words: bicolor; Fluvicola pica; Certhiaxis cinnamomea; Lepidoco- laptes souleyetii; territoriality;breeding; song activity; mangrove;Venezuela.

INTRODUCTION In the tropics, however, most passerineswith Although most studies of territoriality have long-term territories are insectivorous (Rowan been conducted during the breeding season(Ba- 1966, Buskirk 1976, Powell 1980). Arthropods ker and Mewaldt 1979), many species occupy generally have a more uniform spatial distribu- territories year-round (hereafter referred to as tion and are more or less constantly renewed “long-term territories”). This behavior is partic- (Buskirk 1976, Buskirk and Buskirk 1976). For ularly well-developed in the tropics (Robinson birds of seasonal tropical and subtropical habi- 1945, Powell 1980, Karr 1981). For example, tats in South Africa, Rowan (1966) suggestedthat Rowan (1966) found that long-term territories a long-term territorial strategyprimarily ensured were held by nearly 40% of the resident passer- a breeding site for the next reproductive period ines of a tropical region of South Africa. Most and allowed initiation of breeding as soon as studies of the function and settlement periods of environmental conditions were favorable. Such long-term territories, however, have been con- long-term territories were constantly contested ducted in temperate regions, where temporal sta- and modified, advertisement and territorial de- bility and predictability of food resourcesare quite fense persisting throughout the year. However, different. Here, most passerinesholding long-term in highly seasonal tropical habitats, where food territories feed on vegetable matter during the abundance varies greatly over the course of the winter months and, in the absence of renewal year, continuous territorial defense seems un- (Buskirk 1976), their food resources gradually likely. Becausecosts and benefits motivating ter- decrease.Consequently, long-term territories in ritorial defense are influenced by a variety of temperate regions may enhance the survival of factors, such as reproductive activities and rich- individuals during periods of food shortage(Gibb ness of food supply (Brown 1964), some tem- 1960, Brown 1969). Two territorial settlement poral variation should be expected in territorial periods occur annually, one before and one after aggressiveness. the breeding season (Gibb 1960, Brown 1969, Here, we examine the territorial strategy of Knapton and Krebs 1974). four insectivorous passerinesresiding in a highly seasonal tropical mangrove habitat: the Bicol- ored Conebill (Conirostrum bicolor: Emberizi- ’ ’ Received 25 April 1991. Accepted 29 August 1991. dae), the Pied Water-tyrant (Fluvicolu pica: Ty-

P31 84 G. LEFEBVRE,B. POULIN AND R. MCNEIL

Margarita I. 9VENEZUELA H

1/; FIGURE 1. Locationof the studyarea and distributionof the vegetationaccording to coverheight. rannidae), the Yellow-throated Spinetail an upper layer gradually decreasing from 10 to (Certhiaxis cinnamomea: Furnariidae) and the 1 m in height, and finally by a saline mudflat Streak-headed (Lepidocolaptes more or less flooded depending on the season. souleyetii: Dendrocolaptidae). We consider the The study area corresponds to a 5.4 ha plot of periodicity of territorial activities in relation to Avicenniawith highly variable canopy height (Fig. breeding and seasonalfluctuations of food to un- 1). Two distinct zones were observed: one con- derstand the advantages or benefits of maintain- sisting of sparselydistributed, low and stubby (0 ing territories during the non-breeding season. to 3 m high) trees and shrubs; the other formed We ask whether long-term territoriality enhances of denser and more stratified vegetation (3 to 10 survival over periods of food shortage, ensures m high) with an extensive ground cover of pneu- possessionof a breeding site for the next repro- matophores.The area is regularly flooded by tides ductive period, or both. except during a 3-week period in March when the ground dries out completely. STUDY AREA AND METHODS The avian community is composed of per- This study was carried out in a coastal tropical manent residents, occasional visitors (primarily mangrove situated east of Chiguana on the north from adjacent xeric habitats) and Nearctic mi- shoreof the Gulf of Cariaco, in the State of Sucre, gratory warblers. Most speciesare insectivorous in northeastern Venezuela (10”29’29”N, as mangrove propagules are not consumed by 63”45’OO”W) (Fig. 1). Located in a semi-arid re- passerines(Smith 1987). We report on the four gion (Sarmiento 1976), the study area experi- most abundant resident species.The Bicolored encesa dry seasonfrom November to May, with Conebill is almost exclusively found in man- less than 25% of the average annual rainfall of grove habitats; the Yellow-throated Spinetail and 9 15 mm occurring during this period (cumula- Pied Water-tyrant are specialists of hooded or tive data from the Meteorological Station of Ca- near-water vegetation while the Streak-headed riaco, Ministerio de Obras Publicas, Venezuela). Woodcreeper is found in various habitats in- The mangrove habitat consistsof two mono- cluding , open woods, plantations, sa- specific stands distributed in parallel belts along vannas and arid scrubs (Meyer de Schauensee the shore. From the coast inland, Rhizophora 1970, Phelps and Meyer de Schauensee 1979). mangle, with a canopy averaging over 10 m in The four specieshave a wide distribution in South height, is followed by Avicennia germinans with America (Guianas, Venezuela, Columbia, Peru, LONG-TERM TERRITORIALITY IN TROPICAL PASSERINES 85

TABLE 1. Number of individuals,captures, observations and stomachcontents for eachspecies.

Number of Number of Number of Number of Snecies individuals camures observations stomachcontents BicoloredConebill 13 92 59 107 Yellow-throatedSpinetail : 31 112 27 Streak-headedWoodcreeper 54 26 16 Pied Water-tyrant 15 53 145 17

and Brazil, plus Bolivia, Argentina and Uruguay The diet of each specieswas evaluated once a for some species;Meyer de Schauensee 1970). month by forcing captured birds to regurgitate through the administration of a 1.5% potassium SAMPLING antimony tartrate solution, following Tomback’s Data were obtained from mist-netting sessions (1975) method. This part of the study was con- scheduled at 2-week intervals and direct obser- ducted 500 m away from the primary mist-net- vations over two annual cycles: December 1984 ting site to avoid any disruption of territorial through December 1985, and September 1986 activity. through August 1987. All mist-netting sessions lasted two days in DEFINITION OF TERRITORY 1984-1985 and one day in 1986-1987 for a total In this paper, the term territory is used in the trapping effort of 5,250 and 5,244 net-hr respec- ecological context of an exclusive area, as ad- tively. Along two transects 50 m distant, we vanced by Pitelka (1959) and adopted by many placed 14 mist-nets (14 x 3 m, 32 mm mesh) authors (Kaufmann 1983). As defined by Schoe- every50min1984-1985,and23mist_netsevery ner (1968), “the fundamental importance of ter- 25 min 1986-1987. Wecouldthus(l)determine ritory lies not in the mechanisms by which the the breeding seasonof each bird species(by the territory becomesidentified with its occupant(i.e., occurrence of brood patches on adults and the overt defense or any other action), but rather in presenceofjuveniles), (2) mark all captured birds the degreeto which it is in fact used exclusively individually with a numbered metal band and a by its occupant.” This ecological definition is unique combination of four coloredplastic bands, well-adapted to tropical resident birds which and (3) obtain data for territorial cartography rarely sing and are involved in only scarceago- using the net location of each captured and re- nistic territorial interactions (Orians 1969, Karr captured bird. 198 l), particularly speciesholding long-term ter- During 432 hours of observation, the location ritories (Willis 1972, Nunn and Terborgh 1979, of each banded individual sighted was noted on Beehler and Pruett-Jones 1983, Greenberg and a map. A mean point location was used for mo- Gradwohl 1986). Thus, although some territorial bile individuals to eliminate any temporal con- aggressivenesswas occasionally observed, it was tingenciesbetween location points, a factor which not distinctly used in delimiting territorial affectsall territorial representationmethods (Ford boundaries. and Myers 198 1). The presenceof vocalizations REPRESENTATION OF TERRITORY (song, calls), nests, pair bonds, familial groups and flocks were also noted. Territorial areaswere determined by the method During each mist-netting session, the abun- suggestedby Jennrich and Turner (1969) and dance of arthropods (the main food resource Mazurkiewich (1969). Using all location points available) was evaluated by sweep samples. Al- obtained through mist-netting and direct obser- though this is a questionable method for esti- vation, the two principal axes translating the mating the absolute value of arthropod abun- greatestvariance ofthe cloud of points were iden- dance, it is very useful in assessing seasonal tified to define an elliptical area based on binor- fluctuations (Janzen 1973). The first three meters ma1 distribution. This method has been widely of vegetation surrounding mist-nets were swept used for home range studies in mammals (Rod- for 10 min using a standard muslin net. gers and Martin 1986, Anderson 1988) reptiles By this method, we captured primarily the ar- (Schoener and Schoener 1982), fish (Tytler and thropods exploiting the foliage, twigs, and bark. Holliday 1984) and even (Brakefield 86 G. LEFEBVRE. B. POULIN AND R. MCNEIL

500 RESULTS BREEDING ACTIVITY AND FOOD ABUNDANCE g 400 breeding season In the four species,breeding activities (nest con-

; h 1 struction, brood patch development, presenceof juveniles and family groups) occurred in both years from late May to late August. This is con- sistent with results obtained for the same species in Trinidad and Tobago (Herklots 196 1, ffrench 1980) and southwestern Venezuela (Herrero 1989). Variation in food abundance was also highly seasonal(Fig. 2). Arthropod numbers were min-

04 ::: :: :::::::::::::::::I imal from mid-March to mid-June and gradually J F M A M J JASOND increased until January. Some 60% of all cap- FIGURE 2. Seasonal variation in the number of tured arthropods were flying insects(Homoptera, sweep-nettedarthropods (pooled data for both years). Diptera, Coleoptera, Orthoptera, Heteroptera, The horizontal bar correspondsto the period of breed- Neuroptera and Lepidoptera) whereas the re- ing activities of the four species. mainder were non-flying arthropods (Formici- dae, larvae, Araneae, Isopoda, and Coleoptera). As the proportion of each arthropod taxa found 1982). Because of its lack of bias and high sta- within the sweep samples was positively corre- tistical stability, the Jennrich-Turner method lated (rs = 0.63, P < 0.01) with the proportions clearly surpassesthe minimum convex polygon observed in the overall regurgitation samples technique (Jennrich and Turner 1969, Ford and (Table 2) sweep-netted arthropods should pro- Myers 198 1, Worton 1987, White and Garrott vide a reasonable estimate of the seasonal vari- 1990) traditionally used in bird studies (Ruth ation in food abundance to which birds were and Root 1970, Franzblau and Collins 1980, Vil- submitted over the course of the year. Thus, we lage 1982, Loman 1984, Woltom 1985, Yama- can assumethat the breeding seasonbegan when gishi and Ueda 1986, Smith and Shugart 1987). food abundance was minimal and ended when STATISTICAL ANALYSIS still plentiful. All individuals selectedfor representation of ter- ritories were adults observed or captured at least REPRESENTATION OF TERRITORY four times within a two month period (Table 1). A territory generally represents only part of the We calculated a mean location point for each home range of an individual (Brown and Orians individual and each fourteen day period and sub- 1970, Tryon and MacLean 1980, Ferry et al. mitted these coordinates (grouped by bird spe- 198 1, Wiens et al. 1985) and, consequently, an cies and by year) to an agglomerative chrono- exclusive territorial area should include most, logical cluster analysis (CCA) (Legendre and but not all, bird activities. As the Jennrich-Tur- Legendre 1984). The CCA is useful for identi- ner method is based on a binormal distribution, fying discontinuities exhibited by data collected we could determine a theoretical probability for along a temporal gradient. Discontinuities could producing non-overlapping ellipses. After an ex- either represent territorial settlement periods ploratory treatment of the data, a probability of (departure, arrival, or displacement of many in- 60% was selected.These non-overlapping ellip- dividuals) or modifications in the spatial use of ses include 80% of the location points and rep- territorial areas (concentration of activities on a resent an area where 80% of the activities of part of the territory for a certain period). There- territorial individuals were carried out. The dif- fore, a graphic representation of all territories for ference between the binormal and the observed each group of dates produced by the CCA was distributions indicates a more concentrated use necessary to interpret these temporal disconti- of space by individuals, reflecting their attach- nuities. ment to territorial area. These results are con- LONG-TERM TERRITORIALITY IN TROPICAL PASSERINES 87

TABLE 2. Number of arthropodsfrom eachtaxa found in bird stomachsand sampledby the sweep-net.

Bicolored Yellow-throated Streak-headed Pied Arthropod tam Conebill Spinetail Woodcreeper Water-tyrant All four species Sweep-net Coleoptera 192 12 18 21 243 1,015 Diptera 8 2 0 2 12 1,317 Hymenoptera 46 41 27 33 147 1.794 Homoptera 18 20 0 45 83 11479 Larvae 95 22 6 2 125 730 Orthoptera 7 4 2 1 14 399 Heteroptera 4 2 0 1 382 Isoptera 0 118 0 119 0 Lepidoptera 10 9 0 9 28 147 Odonata 0 0 3 4 0 Neuroptera 0 0 0 0 156 Araneae 24 27 3 9 6: 375 Gastropoda 2 0 0 0 2 0 Crabs(Ucu thuyerz] 0 1 0 2 0 Acarina ; 0 0 0 Isopoda 3 0 0 0 3 111 Total 410 142 175 126 853 7,905 Correlationa 0.802** 0.752** 0.243 0.720* 0.633* - aSpearman rank correlationbetween the protwrtion of eacharthropod tam found in the bird stomachsand the proportionsampled by the sweep- net. *P < 0.01. **P < 0.001. sistent with those obtained by Tryon and CCA identified a single temporal discontinuity MacLean (1980) for short-term territorial Lap- corresponding to a territorial settlement period land Longspurs (Calcarius lapponicus), where in early September. Prior to this date, four dis- only 65 to 83% of the activities of individuals tinct territories were occupied by the pairs AB, were observed within the territory. CD, FG and the individual E (the latter either unpaired or paired with a non-banded individ- TERRITORY SETTLEMENT ual). In early September, the territorial mosaic All territories occupied during the periods of was strongly modified. Individuals A, C, D and temporal stability, as identified through the CCA, E disappeared, and new individuals, H and I, are presented for each speciesand both annual were observed. Two pairs were then identified, cycles(Fig. 3). Only the temporal discontinuities BH and FG, the latter holding a much larger corresponding to territorial settlements are in- territory than they had the previous year. For the dicated. Periods of stability in the territorial mo- second year, the CCA did not identify any tem- saic extended over several months for all four poral discontinuity correspondingto a territorial species.Territories are generally paired, with two settlement period. Therefore, the territorial mo- individuals sharing a large portion of their re- saic remained stable from early Septemberto late spective territorial areas, but showing little over- August, as in 1984-1985. Three pairs were then lap with neighboring pairs. These associations observed; BJ, KL and GM. Only individuals B are consideredpairs because,in addition to shar- and G settled their territories in the same area ing the same activity area, individuals were feed- as the previous year. ing or moving together in 30% of the caseswe For Yellow-throated Spinetails in 1984-1985, observed.Also, the observation of brood patches a single territorial settlement period occurred in (primarily limited to females in passerines)dur- late July. Prior to this date, territories were oc- ing the second annual cycle showed that seven cupied by the pair AB and the individual C. From of the eleven pairs observed that year were male- the end of July, the previous territory of indi- female associations.Three of the four remaining vidual C was occupied by the pair EF and in- pairs copulated, used the same nest, or fed the dividual B was replaced by D. During the second same nestlings. year, the CCA did not identify any territorial For Bicolored Conebills in 1984-1985, the settlement period. From September through Au- 88 G. LEFEBVRE, B. POULIN AND R. MCNEIL

Conirostrum bicolor

‘D~J’F’M’A~M~J’J’A’SiDiNlOlJ F M A M J J A’S’O’N’O’J’F’M’A’M’J’J’A’

Certhiaxis cinnamomea

I ,

‘O’J’F’M’A’M’J’J’A’S’O’N’D’J F M A M J J A’S’O’N’D’J’F’M’A’~‘J’J’A’

Lepidocolaptes souleyeti i

‘D’J’F’M’A’M’J’J’A’S’OrN’D’J F n A M J J’A’S’O’N’D’J’F’M’A’M’J’J’A’

Fluuicola pica

~D~J’F’M~A~M~J’J’A’S’O’N’D’J F’M A M J J A’S’O’N’O’J’F’M’A’M’J’J’A

I I I I 1984 1985 non-sampled per,od 1986-1987 FIGURE 3. Representationof the territorial mosaic of eachspecies over two annualcycles. Rectangles represent the study area and letters refer to individual birds. Ellipses correspondto the territorial areasand, when too few observations were made, the individual location points are represented by “+” symbols. Horizontal bars represent the period of stability of the territorial mosaic as identified by the chronologicalcluster analysis.

gust, three territories were occupied by the pairs 1985 AB pair separated and formed two new EG, AD and HI, with individuals E, A and D pairs in 1986-1987, occupying the entire study using the same territorial areas as the previous area. year. The territorial behavior of Pied Water-tyrants Streak-headed were observed was quite different. The CCA identified a terri- and captured less frequently than individuals of torial settlement period before the breeding sea- other species(Table 1). Nevertheless, the CCA son, at different times each year. In 1984-1985, identified a discontinuity correspondingto a ter- territorial settlement was in mid-March. Prior to ritorial settlement period in early September this date, only the pair AB had a well-defined 1985. Before this date, two well-defined terri- territory and after that period, individual B dis- tories were occupied by the pairs AB and CD appeared,individual A moved and formed a new whereas after that period, observations of terri- pair with individual C, and a new GH pair and torial individuals indicated their displacement or DEF associationwere observed. In mid-septem- desertion. In the second year, no territorial set- ber, after the breeding season,a progressivedis- tlement occurred, two territories being occupied mantling of the territorial mosaic led to a tem- by the pairs AE and BF year-round. The 1984- poral discontinuity. However, the latter is not LONG-TERM TERRITORIALITY IN TROPICAL PASSERINES 89 indicated in Figure 3 because it does not corre- d 30+ Conirostrum bicolor spond to a territorial settlement period, but to a ; decreasein the size of the territorial space used zi, and the departure of some individuals not re- JFMAMJJASOND placed. All Pied Water-tyrants finally deserted the study area from mid-November to mid-De- 6 30 Certhiaxis cinnamomea 5 20 cember. For the secondyear, the CCA identified t / a territorial settlement period in mid-January. : : : : : : ’ S 0 N D Preceding this date, only individual I was ob- JFMAMJJA served sufficiently to be considered as holding a territorial area, whereasindividuals N and 0 were 6 30 Lepidocolaptes souleyetii .E 20 observed far away from their eventual territory. t After mid-January, three well-defined territories s$_ :e_\ : ( JFMAMJJASOND were held by the pairs JK, LM and NO. How- ever, not all theseindividuals were present in the 2 30.‘ Fluvicola pica study area in mid-January. In fact, the CCA iden- .- 20.. tified only the onset of the territorial settlement period which actually extended into late Feb- JFMAMJJASOND ruary, being a more protracted phenomenon in FIGURE 4. Temporal variation in the frequency of this speciesthan in the other three. vocalizations of each species (pooled data for both years). VOCALIZATIONS Temporal variations in the frequency of vocal- izations of each specieswere summed over both 0.001) between temporal vocalizations of Pied annual cycles (Fig. 4). Songsand call notes were Water-tyrants and Yellow-throated Spinetails, pooled becausebirds rarely sang(38 vs. 622) and two speciesexhibiting different territorial strat- the periodicity of both behaviors was similar in egies. all species(G-test, df = 11, ns). The frequency of vocalizations in Bicolored Conebills was rel- DISCUSSION atively high and more or less constant through- For each speciesstudied, a single period of ter- out the year, with a slight decreasein the middle ritorial settlement occurred during each annual of the breeding season (June-July). In Yellow- cycle. In the first year, territories of Bicolored throated Spinetails, vocalizations varied greatly; Conebills, Yellow-throated Spinetails and Streak- they were high during the breeding season,max- headed Woodcreepers were settled after the imal soon after the territorial settlement (Sep- breeding season,from late July to early Septem- tember) and minimal during the non-breeding ber. For the second year, the territorial mosaic period. Vocalizations were low in Streak-headed of each speciesremained stable year-round (from Woodcreepers, with a slight increase before the September through August). However, strong breeding season and over the territorial settle- modifications in the spatial distribution of birds ment period. Song levels in Pied Water-tyrants between December 1985 and September 1986 were highly seasonal and largely limited to the suggestthat new territories were settled during breeding season,with a peak during the period the non-sampled period. Thus, in both years, of juvenile dispersal. Therefore, the settlement Bicolored Conebills, Yellow-throated Spinetails period of this short-term territorial specieswas and Streak-headed Woodcreepers probably es- not related to a higher rate of vocalizing. tablished territories immediately after breeding Each specieshad its own seasonal pattern of and maintained them throughout the rest of the vocalizations without regard to territorial strat- year. For Pied Water-tyrants, on the other hand, egy. No significant correlation (r = -0.24 to 0.54; the territorial settlement took place before the II = 12, ns) appearedbetween temporal vocaliza- breeding season,from late February through mid- tions of the three speciesholding long-term ter- March. After breeding, a decreasein territorial ritories. In contrast, the analysis revealed a high- spaceused and a gradual dispersal of territorial ly significant correlation (r = 0.85; IZ = 12; P < individuals progressively dismantled the terri- 90 G. LEFEBVRE, B. POULIN AND R. MCNEIL torial mosaic. The use of territory by Pied Water- abundance during the dispersal of juveniles im- tyrants is thus a seasonalphenomenon confined mediately after breeding favor an increasedcom- to the breeding period. petition for space(Brown 1964). Most territorial settlementswere characterized Territorial mosaicsin the study area remained by marked changesin territory owners as well as stable during periods of low food abundance, in in the configuration and location of territories. contrast to results from temperate regions (Dix- Modifications of territorial mosaics were es- on 1949, Snow 1956, Gibb 1960, Davies 1976). pecially noticeable in the single species which Moreover, breeding was initiated while food used a short-term territory: none of the fifteen abundance was minimal. Thus, food availability Pied Water-tyrants maintained the same terri- is probably not as crucial a limiting factor for tory for more than one breeding season com- these tropical resident speciesas it is for long- pared to 25% (7/28) for species holding long- term territorial residents at temperate latitudes. term territories. This proportion, however, is low Consequently, considering the high stability of comparedto the 40% observedby Dowsett (1985) territorial mosaics even during periods of low and the 54-75% found by Greenberg and Grad- food abundance and the absence of territorial wohl(1986) for tropical resident passerineswhere settlement before breeding, we suggestthat ter- territorial modifications were strictly due to in- ritoriality during the non-breeding period in Bi- dividual mortality. An experimental study on coloredConebills, Yellow-throated Spinetails and Song Sparrows(Melospiza melodia) by Knapton Streak-headed Woodcreepers functions primar- and Krebs (1974) revealed that a synchronous ily to ensure a breeding site for the following year. territorial settlement, in contrast to a gradual re- placement of individuals, involved strong mod- ACKNOWLEDGMENTS ifications of the territorial mosaic, favoring a This study was supportedby the Natural Sciencesand higher density in the territorial population. Thus, Engineering Research Council of Canada, Fonds a long-term territorial strategy, in contrast to a F.C.A.R. (Gouvemement du Quebec),and the Univer- short-term one, may favor territorial individuals site de Montreal. We are grateful to Pierre Drapeau and John Wiens for their valuable comments on the by promoting successive reproductions in the manuscript, to Pierre-Paul Harper for his help in iden- same area, while a single period of territorial tifying arthropods, and to Francine Mercier and Lucia contestfor all birds of a given speciescould favor Carpineta for improving the English. We are also in- non-territorial individuals by increasing modi- debted to colleaguesof the Universidad de Oriente, and in particular, to JoseRamon Rodriguez Silva, who fications in territory owners. was co-responsiblewith McNeil for the collaboration Temporal variation in vocalizations differed between the two universities. greatly among species,regardless ofthe territorial strategyinvolved. Moreover, although the breed- LITERATURE CITED ing seasonwas confined to the same three-month period (May-August), the periodicity of vocal- ANDERSON,E. M. 1988. Effects of male removal on izations was quite variable among the four spe- spatial distribution of bobcats. J. Mammal. 69: 637-641. cies. Data such as nest attendance, presence of BAKER,M. C., AND L. R. MEWALDT. 1979. The use brood patches and first occurrence of juveniles, of spaceby White-crowned Sparrows:juvenile and thus seem necessaryto determine accurately the adult rangingpatterns and home rangeversus body breeding seasonof long-term territorial species. size comparison in an avian granivore commu- nity. Behav. Ecol. Sociobiol. 6:45-52. For the three speciesholding long-term terri- BEEHLER.B., AND S. G. PRUETT-JONES.1983. Disulav tories, a single settlement period occurred im- dispersion and diet of birds of paradise: a corn’- mediately after the breeding season. Territories parison of nine species. Behav. Ecol. Sociobiol. were not settled again prior to breeding as ob- 13:229-238. BRAKEFIED,P. M. 1982. Ecological studies on the served at temperate latitudes (Gibb 1960, Brown butterfly Maniola jurtina in Britain. 1. Adult be- 1969, Knapton and Krebs 1974). During the pre- haviour, microdistribution and dispersal.J. Anim. breeding period (April-May), food abundance Ecol. 5 1:713-726. was minimal in the study area (in contrast to BROWN,J. L. 1964. The evolution of diversity in temperate regions) and it would have been dif- avian territorial systems.Wilson Bull. 76:160-l 69. BROWN,J. L. 1969. Territorial behavior and popu- ficult for individuals to invest the time and en- lation regulation in birds. A review and releval- ergy necessaryfor territorial establishment. Al- uation. Wilson Bull. 81:293-329. ternatively the high population density and food BROWN,J. L., AND G. H. ORIANS. 1970. Spacingpat- LONG-TERM TERRITORIALITY IN TROPICAL PASSERINES 9 1

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