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1 Butterflies are frequently used to investigate Neotropical diversity, but the family Hesperiidae is almost never employed as a focal group. Sampling Hesperiidae with artificial lures has been used to assist in species richness estimates of males that use bird droppings as a resource, but its effectiveness for estimating total hesperiid site diversity is unknown. 2 This study characterises species richness and abundance in a diverse assemblage of Hesperiidae sampled at artificial lures. Sampled and estimated richness among taxonomic subsets were compared to the known site richness. These comparisons are used to assess artificial lures as a method for sampling total richness of Hesperiidae. We tested for potential differences in attraction in lures placed with and without the presence of army ant swarms. 3 Five years of intermittent sampling with lures recovered 65% of the known Hesperiidae species richness at the study site. We found the subfamilies were differentially attracted to lures, where 86% of Eudaminae, 56% of Hesperiinae and 55% of Pyrginae species known from the site were recovered by lures. Species accumulation and taxonomic diversity differed among lures placed alone, and those placed in the presence of army ants. 4 Our results suggest that sampling with artificial lures can be used to estimate diversity of Neotropical Eudaminae and a few tribes of Hesperiinae at some sites. Available evidence indicates that Hesperiidae feeding at bird droppings is predominately a Neotropical phenomenon. Finally, we conclude that estimating diversity in Neotropical Hesperiidae will require long-term studies that use multiple sampling techniques.

A sample of over 400 co-occurring species of Neotropical Hesperiidae attracted to artificial lures was used to test for temporal structure among species and explore potential consequences of temporal partitioning within assemblages. Five years of intermittent transect samples at the same site revealed that diel activity was significantly partitioned among subfamilies, genera and species within this species assemblage. Calculations of reproductive isolation indicate that partitions in activity times are sufficient to provide significant prezygotic reproductive isolation among some congeneric species pairs. Temporal patterns in this assemblage are considered in light of field observations and temporal partitions are examined as a potential isolating barrier among insects. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society 2008, 94, 723–736.

A new species of Parelbella is named and described. It is known from the states of Veracruz and Oaxaca, Mexico, and may be endemic to the southern Sierra Madre Oriental.

Helicoverpa zea (Boddie) (Noctuidae) is a well-documented pest of agricultural crops throughout most of North and South America (Wilcox et al. 1956; Hardwick 1965, 1996; Kimball 1965; Tietz 1972; Covell 1984; Heppner 2003; Capinera 2005; Wagner 2005). Hardwick (1965), in proposing the genus Helicoverpa as distinct from Heliothis Ochsenheimer, noted the polyphagous herbivory of H. zea (see also Kimball 1965; Tietz 1972; Covell 1984; Heppner 2003; Capinera 2005; Wagner 2005), but made no mention of predaceous behavior within the genus. Cannibalism was reported by Hardwick (1996) as common by young larvae of Heliothinae, particularly for individuals feeding in small flower heads. Capinera (2005) noted that aggressive killing and cannibalism occurs in late instar larvae of H. zea when occupying ears of corn. Hardwick (1996) documented a case of intergeneric predation in larval Heliothinae, where Euticropis nexilis Morrison (Noctuidae) was consumed by Schinia verna Hardwick (Noctuidae) when feeding within flower heads of Antennaria (Asteraceae) (see also Hardwick 1958, 1970). Huguenin (1914) documented a case of interfamilial predation where larvae of Heliothis dispaceus [sic] (Noctuidae) killed and consumed pupae of Pieris rapae (Linnaeus) (Pieridae) in captivity. The aforementioned represent the only previously documented carnivory by Heliothinae. Additional records of carnivorous behavior and the first known occurrence of interfamilial predation by larvae of Helicoverpa are reported herein. On 10 August 2006 an unidentified larva of Noctuidae, determined after eclosion as H. zea, was discovered feeding upon a final instar larva of Cyclargus thomasi bethunebakeri (Comstock and Huntington) (Lycaenidae) (generic nomenclature follows Nabokov 1945) reared within a captive laboratory culture located in J Insect Behav (2008) 21:143–146 DOI 10.1007/s10905-007-9113-0

Native riparian habitats cover a small percentage of the landscape in most arid lands. Irrigation, however, artificially expands these in some regions. It is important to understand whether human-modified landscapes can support species native to natural ecosystems. We examined butterfly communities in relatively undisturbed (nonagricultural) versus artificially created (agricultural) riparian habitats in the Walker River Basin in the western Great Basin (Nevada and California, USA). Habitat type did not significantly affect species richness. Butterfly abundance was greater, and evenness lower, in agricultural than in nonagricultural sites. Annual variability significantly affected species richness, total abundance, and evenness. The few species largely restricted to agricultural sites were geographically widespread and characteristic of disturbed habitats. Several relatively uncommon species were not present in agricultural sites. Riparian habitats created to support agriculture may help support some native butterfly species, but cannot substitute for undisturbed riparian habitats.

We examined the response of montane butterflies to a 1300-m elevational gradient in the Toiyabe Range, a mountain range in the central Great Basin. We tested whether elevational ranges of montane butterflies conform to Rapoport’s elevational rule (species at higher elevations have greater elevational ranges). We also tested whether the Rapoport-rescue hypothesis (emigrants from higher elevation populations inflate the species richness of lower-elevation sites) could explain the species richness patterns we observed. In addition, we predicted whether global climate change is likely to perturb current elevational gradients in butterfly species richness. Species presence data were collected from 105 100-m vertical elevational bands in 17 canyons. Elevation and species richness were significantly negatively correlated, although species richness peaked at intermediate elevations, and butterflies in species-rich areas had significantly narrower elevational ranges than species in more depauperate areas. Toiyabe ...

Fifteen species of Aguna Williams, 1927 (Hesperiidae: Pyrginae) are known from near Cacaulandia in central Rondonia, Brazil; nine represent undescribed species. These nine, plus four additional new species discovered among material from other areas, are named and described: Aguna latifascia, Aguna coeloides, Aguna nicolayi, Aguna latimacula, Aguna penicillata, Aguna spicata, Aguna longicauda, Aguna panama, Aguna spatulala, Aguna similis, Aguna mesodenlala, Aguna squamalba, Aguna parva. The species of Aguna are placed into ten species groups based upon the characters of the male and female genitalia. These groups are described and their included species are discussed. Aguna williamsi Hayward, 1935, new synonymy is considered synonymous with Eudamus glaphyrus Mabille, 1888, revised status. Goniurus hypozonius Plotz, 1880, new status is considered a subspecies of Eudamus aurunce Hewitson, 1867. Neotypes are designated for Goniurus cholus Plotz, 1880, Papilio coelus Stoll, [1781], Goniurus gideon Plotz, 1880, and Goniurus hypozonius Plotz, 1880. Lectotypes are designated for Eudamus asander Hewitson, 1867, Eudamus panthius Herrich-Schaffer, 1869, Eudamus scheha Plotz, 1882, Eudamus mega-clesMabille, 1888, Eudamus leucogramma Mabille, 1888, Hesperia metophis Latreille, [1824], Eudamus aurunce Hewitson, 1867, and Eudamus glaphyrus Mabille, 1888. Preliminary identification keys are provided.

Stinga Evans, 1955, has been considered monotypic since its description despite geographical variation that has not been elucidated. The variation of Stinga morrisoni (W. H. Edwards, 1878) described and figured here includes a range of superficial phenotypes segregated by a combination of geography and elevation, but united by a common genital morphology of both sexes. In addition, a second species of the genus occurring in southern Mexico (Tlaxcala, Puebla and Oaxaca), with different genitalia and superficial traits outside the range of variation seen in S. morrisoni, is described and named as a new species.

A new species from northeastern Mexico, Neominois carmen (Lepidoptera: Nymphalidae: Satyrinae), is described, illustrated, and compared with its only known congener, N. ridingsii. The species is distinguished from the latter by its orange coloration and shape of and pattern on the wings as well as by differences in the genitalia of both sexes.

Examination of more than 600 specimens of Copaeodes minima (W. H. Edwards, 1870) (Hesperiidae: Hesperiinae) indicated phenotypic variation throughout its distribution. A dark form occurs in response to low temperatures during development. Its genitalia do not vary concomitantly. Both C. minima and its synonym, Copaeodes rayata Barnes & McDunnough, 1913, were described from the pale form of the species. A lectotype is designated for Copaeodes rayata.

The species of Cephise Evans, 1953 are divided in two groups: "cephise" group (hind wing without long tails) and "procerus" group (hind wing with long tails). In the "cephise" group the following species are included: Cephise cephise (Herrich-Schäffer, 1869) with his synonyms Thymele hydarnes Mabille, syn.n., Eudamus zopyrus Plötz, 1881, Telennades injuncta Plötz, 1882, nom. nud., Eudamus maneros Mabille, 1883, syn.n., Nascus orima Schaus, 1902, syn.n., Nascus orita Schaus, 1902; Cephise impunctus sp.n. from Rondônia, Brazil; Cephise glarus (Mabille, 1888), sp. reval.; Cephise nuspesez Burns, 1996; Cephise malesedis sp.n. from Rondônia, Brazil; Cephise maculatus sp.n. from Rondônia, Brazil; Cephise burnsi sp.n. from Espírito Santo, Brazil; Cephise mexicanus sp.n. from Oaxaca and San Luis Potosi, Mexico. In the "procerus" group are included: Cephise procerus (Plötz, 1880); Cephise aelius (Plötz, 1880) sp. reval.. comb.n.. with its synonyms Eudamus auginulus Godman & Salvin, 1893, syn.n. and Eudamus callicina Schaus, 1902, syn.n.; Cephise callias (Mabille, 1888); and Cephise guatemalaensis (Freeman, 1977). Lectotypes are designated for Eudamus cephise Herrich-Schäffer, 1869, Thymele hydarnes Mabille, 1877, Telegonus glarus Mabille, 1988, Eudamus callias Mabille, 1888, Goniurus procerus Plötz, 1888, and Goniurus aelius Plötz, 1880. Neotypes are designated for Eudamus zopyrus Plötz, 1881, and Thymele maneros Mabille, 1883. A pseudotype of Thymele hydarnes is identified, this is actually a female of Cephise impunctus sp.n. Six species of Cephise occur sympatrically in Rondônia, Brazil.

Butterfly species lists were assembled for 18 Great Basin mountain ranges for which distributional data on mammals and birds have been analysed previously by other workers. The ranges represent remnant islands of the boreal habitat that once was continuous across the Great Basin but is now restricted to higher elevations as a result of climatic change at the close of the Pleistocene. The effects of biogeographic factors (area, distance, elevation) and habitat diversity on butterfly species number were examined. The Great Basin boreal butterfly faunas were found to be depauperate overall relative that of the principal mainland source, the Rocky Mountains, and were found to have fewer species than predicted by the mainland species-area data. However, only a weak area effect, and no distance effect, was detected by bivariate and multivariate analysis. Furthermore, the habitat diversity score found to explain virtually all the variation in bird species number in the same ranges in previous studies is only marginally significantly correlated with butterflies. When the butterflies are subdivided according to their vagility, the relative differences in the species-area correlation and slope (z-value) between the vagility categories were consistent with those found previously for mammals and birds, and, as predicted by theory, less vagile taxa exhibit higher species-area correlations and z-values. Overall, differences in the insular biogeography of buttterflies and vertebrates seem to reflect fundamental ecological differences between the taxa.

Summary Austin, G. T. 1979. Pattern and timing of moult in penduline tits (Anthoscopus). Ostrich 49:168-173. Moult was examined in species of Anthoscopus. Second and subsequent prebasic moults were complete. Primary and rectrix moult was typical of passerines, but secondary moult was some what irregular. Moult was largely non-overlapping with breeding, although some body moult was noted during the breeding season. In southern Africa there was some regional variation in timing of moult. First year birds moulted after adults had largely completed feather replacement. This first prebasic moult was incomplete.

The relative-abundance component (J') of diversity in avian communities during the breeding season was shown to be high in comparison to those for plants and phytoplankton (Tramer 1969). While analyzing some of our unpublished bird-population data (Austin, southern Nevada; Tomoff, southern Arizona), we noted that relative abundance remained at this high level throughout the year and that species richness (S) and diversity (H') varied. To determine if this is a characteristic of other terrestrial avian communities, we censused several areas in southern Arizona during winter and analyzed other nonbreeding bird-population data from the literature. Some seasonal variation in J' has been noted for birds (Kricher 1972). Consequently, Austin's southern Nevada data were also examined.

The recent occurrence in western North America of wood warblers normally considered to be eastern migrants, especially in the fall, has been well documented by McCaskie and Banks (1964), Tenaza (1967), McCaskie (1970a, b), and others (see especially Audubon Field Notes). In light of the large number of records of these birds on the west coast, it is of interest to examine them from the standpoint of season and timing of occurrence and to contrast these with the usual migratory timing on the east coast. Comments are also made on the status of these species in the West.

Few studies of bird populations have been undertaken in desert communities. Previous studies in North American warm deserts were conducted by Hutchinson and Hutchinson (1941, 1942), Robert (1967), and Sheppard (1968) in California; Hensley (1954) and Tainter (1965) in Arizona; Raitt and Maze (1968) in New Mexico; and Dixon (1959) in Texas. Davis (1963) and Webster (1964) censused desert areas in Mexico. No study has been conducted in the northern Mohave

DURING THE last year in college, chemical engineers about to graduate ask again and again, "Now that I am about to become a chemical engineer, what will I do?" All young men starting in new work have this same dilemma to a greater or lesser degree, but with chemical engineers it seems to be particularly difficult because of the breadth and newness of the field. The first major difficulty which can be expected is confusion and difficulty in discovering not only what he is about to do but also exactly what his future goal will be. Just as a traveler can frequently cross half a continent without getting lost only to spend an exasperating hour and a half trying to find a certain house on an unmarked street in a small town, so the young engineer may find his first contacts with the intimacies of his profession confusing. I know men who modestly refer ...

Many biologists tackle only narrow research topics, and test or develop hypotheses just within their re- s~ricted fields. Natural history, exem- p ified by Phil De Vries’ excellent ni?w butterfly book, is seen by many a:; non-productive because it accumulates miscellaneous facts tt-at are relevant to a variety of prob- lems. This view is at least partly wrong, both in biology and in other fields considered to be paradigms of the scientific method. In physics, for example, theory alone did not pre- dizt the existence of the component units within protons and neutrons. Instead, post-war high energy ex- pccriments enjoyed massive funding bcecause of their military potential, as a l.esult of which a baffling variety of new subatomic particles were dis- covered. It was only in the 1960s that MArray Gell-Mann produced the qt.ark theory. He showed how many ‘ strange’ particles, as well as ordin- ar$/ protons and neutrons, could be explained if they were composed of a much simpler array of smaller ‘ quarks’ . The theory was of course mathematical, but its development WZIS similar to that of the theory of natural selection: an accumulation of cai.efully observed facts led to a major explanatory advance. Even to- daf, there is no theory in physics to predict whether or not quarks are themselves composed of yet smaller pa-titles. More ‘ particle natural his- tory’ will probably be needed before such a theory is forthcoming. P/lany areas of evolution and ecol- og>/ are inadequately understood: species diversity and speciation are just two examples. Tropical butter- flies, already so useful in evolution- ary biology, could provide key information. In addition, there are almost certainly questions that we

During ornithological studies in southern Nevada, we obtained noteworthy data on the occurrence and status of several species. Our observations support the suggestion of unstable breeding populations of certain species in the Spring Mountains (Johnson 1965). All records are for Clark County unless specified. Wing and tail measurements are in millimeters. Specimens collected are on deposit in the Biology Museum, University of Nevada, Las Vegas (UNLV) and in the collection of A. M. Rea (AMR), Tucson, Arizona. Additional material from the Museum of Verte

Differential foraging behavior by the sexes has been noted in several woodpeckers of the genus Dendrocopos (Kilham 1965, 1970, Ligon 1968a, 1968b, Jackson 1970, Short 1971, Willson 1970, Koch et al. 1970, Kisiel 1972). One species, the Ladder-backed Woodpecker (D. scalaris) has received little attention although there is a suggestion that the sexes forage in different ways (Short 1971). In this paper, I present data on the foraging of this species gathered from April 1970 through September 1971 on the Santa Rita Experimental Range, Pima Co., Arizona. In addition, comparisons are made with other species of the genus. STUDY AREA AND METHODS

Growth and development of birds have engendered considerable recent interest. Rate of increase in body weight is known for many species (Ricklefs 1968a, 1972), but development of homeothermy (e.g., Kendeigh 1939, Dawson and Evans 1957, 1960, Ricklefs and Hainsworth 1968), relative growth of organs and changes in body composition (Ricklefs 1967a, 1975, Myrcha and Pinowski 1969, Diehl et al. 1972) are poorly known. Few attempts have been made to correlate all these factors in one species (Diehl et al. 1972, Diehl and Myrcha 1973, Ricklefs 1975). Herein, we compare growth and development of the Rufous-winged Sparrow (Aimophila carpalis), which has a short nestling period (8-9 days), to those of the Cactus Wren (Campylorhynchus brunneicapillus), with a nestling period of 20 days (described in detail by Ricklefs and Hainsworth 1968 and Ricklefs 1975).

Since 1961 the author has spent considerable time in the field in Clark County, Nevada. The following records derived from this field work extend our knowledge of certain species which are considered uncommon to rare in southern Nevada. I am grateful to Charles G. Hansen, biologist, Desert Game Range, for access to his personal records and to the Desert Game Range Narrative Reports (DGRNR). All specimens are on deposit in the Biology Museum, Nevada Southern University. Porphyrula martinica. Purple Gallinule. Two individuals of this species were observed at Tule Springs Park, 13 miles northwest of downtown Las Vegas, in 1966. Single birds were observed there on 7, 8, and 20 September and a male (B-668, weight 183.2 g, left testis 8 x 2 mm, no fat) was collected on 8 September 1966. This constitutes the first record for Nevada. Charadrius semipalmatus. Semipalmated Plover. Spring records of this species for Henderson Slough, one mile north of Henderson, on 26 April 1967 (5 birds) and Tule Springs on 12 and 15 May 1967 (1 bird) supplement those of Grater (Condor 41:221, 1939) and Hayward et al. (Brigham Young Univ. Sci. Bull., Biol. Series 3:8, 1963). Fall records for Henderson Slough on 16 August (2 birds), 23 August (1 bird), and 2 September 1966 (2 birds), and for 1.5 miles west of Logandale on 13 September 1966 (10 birds) appear to be the first for this season in southern Nevada. Specimens were taken on 16 August (B-626, female, ovary 5 x 3 mm, weight 47.8 g, heavy fat), 23 August (B-655, female, ovary minute, 42.4 g, heavy fat), and 2 September (B-743, female, ovary 7 x 1.5 mm, 39.2 g, moderate fat). Charadrius alexandrinus. Snowy Plover. This species is an uncommon transient in Nevada. I have records of single birds of Henderson Slough on 16 and 23 August 1966. A female (B-627, ovary 5 x 3 mm, 31.2 g, light fat) was collected on 16 August. These appear to be the first fall records for southern Nevada. Arenaria interpres. Ruddy Turnstone. Alcorn (Condor 44:81, 1942) lists the single previous Nevada record of this species. A male (B-665, left testis 3 x 0.5 mm, 74.4 g, light fat) was collected 1.5 miles west of Logandale on 13 September 1966. Erolia bairdi. Baird's Sandpiper. Hayward et al. (op. cit., p. 9) give the only previous report of this species for southern Nevada. There is an unpublished record for Corn Creek on 22 April 1946 (DGRNR, January-April 1946). I have additional records for three birds 1.5 miles west of Logandale on 13 September 1966 (female collected, B-666, ovary 3 x 3 mm, 32.3 g, light fat) and for one at Tule Springs Park on 2 May 1967. Crocethia alba. Sanderling. The Sanderling has not been reported previously for southern Nevada. I saw a single bird at Tule Springs Park, 1-3 May 1966.

In recent years the author has accumulated records which help to clarify the status of the less common anatids in southern Nevada. I thank the Nevada Fish and Game Department for access to their records, donation of specimens (now on deposit in the Biology Museum, University of Nevada, Las Vegas), and the opportunity to examine hunters' bags at the Overton Wildlife Management Area (OWMA) in Moapa Valley, Clark County, during the 1968-69 hunting season. I also thank C. G. Hansen and R. Wauer for access to their personal records, R. C. Banks for identification of the scoter, and D. L. Pribble for assistance in the field. All locations are in Clark County unless specified. Whistling Swan. Olor columbianus. Previous records have been mainly for the northern part of the state where it winters (Alcorn 1946). Cottamrn (1936) and Zimmerman (1963) gave records for December and January in the south. I have records from 15 October (1968, OWMA) to 1 February (1964, OWMA) on larger bodies of water in Lincoln and Clark counties.

Cody (Condor 70:270, 1968) summarized the present knowledge of interspecific territoriality in hummingbirds. Apparently there is no known instance of interaction between Broad-tailed (Selasphorus platycercus) and Calliope (Stellula calliope) Hummingbirds. Reported here are two instances of interspecific territoriality between males of these two species in the Spring Mountains, Clark County, Nevada. The Broad-tailed Hummingbird is a common breeding bird in the montane forests of southern Nevada (Johnson, Condor 67:103, 1965) and territories are established by mid-May (pers. ohserv.). The Calliope Hummingbird is a rare transient in the same region (Austin, Condor 70:391, 1968). Interactions between the two species were first observed in Lee Canyon, 8900 ft, on 23 May 1966 in an open forest of aspen (Populus tremuloides), ponderosa and bristlecone pines (Pinus ponderosa and P. aristata), and white fir (Abies concolor), with an understory of snowberry (Symphoricarpos sp.) and currant (Ribes spp.). The latter were in bloom and are an important nectar source in spring and early summer. Here a calliope was first observed perched at the tip of a small fir. It flew down to feed on the Ribes several times and once hovered at the tip of a fir branch, apparently catching small insects. It always returned to the perch where it was first observed. A broad-tail flew to a currant about 10 ft from the perched calliope. The latter immediately attacked the former, pursued it up the canyon about 30 ft, and returned immediately to its perch. Shortly, another broad-tail approached from the opposite direction and was similarly pursued for about 15 ft. On both occasions both species called continuously. During the next 30 min, no further encounters were observed, although the broad-tails fed just beyond the point to which they had been pursued. An hour later the calliope, still perched in the same spot, was collected. A week later broad-tails were observed feeding in the area from which they had previously been chased. The second encounter was also in Lee Canyon, 8400 ft, on 3 June 1966. This area is dominated by ponderosa pine and white fir. The canopy is not as open as at the above site and there is less understory. Here another calliope was observed on the tip of a larger fir. Several times it hovered near the tips of branches. A broad-tail flew to a currant near the base of the fir and was pursued for about 20 ft, after which the calliope returned to the fir. No other encounter was observed in the succeeding 20 min. Two hours later the calliope was observed again, still in the same place. These appear to be the first records of interspecific aggression between Calliope and Broad-tailed Hummingbirds and add to the paucity of records of a migrant species occupying habitat which would otherwise be used by a related resident species. 1 Present address: Department of Biological Sciences, University of Arizona, Tucson, Arizona 85721. Accepted for publication 31 October 1968.

During the course of field studies in 1970 on the Santa Rita Experimental Range, Pima County, Arizona, we observed eight instances of interspecific aggression by Ash-throated Flycatchers (Myiarchus cinerascens) on Cassin's Sparrows (Aimophila cassinii). The former is a medium-sized tyrannid which nests in abandoned woodpecker holes in much of the southwestern United States and into M6xico. It forages mainly by hawking for insects from the upper limbs of trees. The sparrow is a ground-foraging species, feeding on seeds in winter and ground-inhabiting insects during the summer. Nests are placed near the ground in low vegetation. Its song is delivered in an upward arching flight from upper limbs of trees. The pattern of singing flights closely resembles the hawking maneuvers of the flycatcher. It was during the flight song that the sparrows were attacked by the flycatcher. The latter flew straight at the sparrow and usually knocked it to the ground. Apparently, the flycatcher was responding to a behavioral image which approximates its own foraging maneuvers. Selection against such behavior is probably weak since Cassin's Sparrow is rather restricted in its distribution and then only occurs in grasslands. On the other hand, strong selection pressures may operate to maintain this type of behavior in the flycatcher since it overlaps several potential competitors (Myiarchus spp., Tyrannus spp.). One other observation adds strength to the above suggestion. A Cactus Wren (Campylorhynchus brunneicapillus), flying about 3 m above the ground, suddenly made an upward jog in its straight line flight. This deviation was similar in form to a flycatcher foraging maneuver. Immediately, an Ashthroated Flycatcher, which was perched about 4 m away, flew at the wren and knocked it to the ground. These data were obtained during research supported by the US/IBP Desert Biome program under grant no. GB 15886 from the National Science Foundation.

birds during winter in north temperate regions is widely recognized (see Morse 1970 for references). However, there have been few attempts to quantify the interspecific relationships of members of foraging flocks. Most previous studies considered foraging behavior of members of the same genus during the breeding season (see Sturman 1968 for references), although Gibb (1954, 1960) discussed the foraging ecology of several species throughout the year, and Morse (1967a, b) studied the foraging ecology of unrelated species in summer and winter, respectively. Notably, Morse (1970) presented extensive data on foraging and interactions of mixed winter flock members in eastern North America.