4. THE SOUTH AFRICAN CLIFF SWALLOW

Short, L.L. &; Horne, J. F. M. 1980, Vocal and other behaviour of the Green Barbet in Kenya. Ostrich 51:219–229.

Brief field studies of the Green Barbet Stactolaema olivacea in coastal Kenya, with emphasis on vocalizations, document its social behaviour, including communal roosting of four birds in a cavity. Green Barbets are aggressive, interacting strongly with a number of species. Erecting of the crown feathers, cocking of the tail, and woodpeckerlike swinging movements characterize displays. Wing Flutters and audible Bill Wiping are visual-auditory displays. Vocalizations include the Grating Call, Kek Call, Chuk Call and Chowp Call. These are agonistic and agonistic-reproductive in function. The Chowp Call comprises the song, used in simultaneous singing and duetting.     

Diversity and status of sea turtle species in the Gulf of Guinea islands

In West Africa, the Gulf of Guinea islands are important nesting places for four sea turtle species. The Green turtle (Chelonia mydas), the Hawksbill (Eretmochelys imbricata), the Olive Ridley (Lepidochelys olivacea) and the Leatherback (Dermochelys coriacea) turtles nest on Bioko's southern beaches. The Green, Hawksbill and Leatherback turtles breed on Príncipe and São Tomé. The Leatherback turtle nests, at least, on Annobón. The Leatherback turtle is reported on the four islands for the first time, and the Olive Ridley turtle for Bioko. Bioko is probably the most important island in terms of number of species and nesting individuals; the Green turtle being the most abundant species. However, the nesting places are at present restricted to barely 20 km along the coastline. On Príncipe and São Tomé, the most common species is the Hawksbill turtle. Sea turtle nesting populations are being severely depleted on the four islands. The main causes of cverexploitation are the meat and egg trade on Bioko and the Hawksbill shell-craft trade on São Tomé and Príncipe.     

Vocal Diversity and Taxonomy of Nomascus in Cambodia

It is usually thought that Nomascus gabriellae is the only Nomascus sp. in Cambodia. We studied vocal diversity among different wild populations of Nomascus in Cambodia to assess their taxonomic relationships and to examine whether their vocal patterns correspond to forms previously described for Nomascus leucogenys siki and Nomascus gabriellae. We tape-recorded crested gibbon songs in southern Mondulkiri Province, in central Rattanakiri Province, and in 2 different districts of the Virachey National Park in northern Rattanakiri. We also tape-recorded typical songs of Nomascus leucogenys siki near the type locality of the taxon in the Bach Ma National Park in central Vietnam. We analyzed 40 song bouts from different gibbon groups, including 151 phrases of 33 females and 235 phrases of 39 males. Discriminant analyses revealed marked separation of the most southern songs (Mondulkiri) from those of all other localities. Vocal differences among the 3 gibbon populations in northeast Cambodia (Rattanakiri) are less pronounced; they do not differ more among each other than each of them differs from the northernmost sample from Bach Ma (Vietnam). Vocal characteristics of the study populations revealed no cline, and populations do not differ significantly in vocal variability. We conclude that Cambodian crested gibbons represent 2 distinct taxa: Those from southern Mondulkiri are Nomascus gabriellae, those from northeast Cambodia (Rattanakiri) closely correspond to the sample from Bach Ma (Vietnam) and, together with the latter, represent a different taxon. We provisionally assign them to Nomascus leucogenys siki because of the close geographic distance between Bach Ma and the type locality of the taxon. We postulate that a taxonal boundary exists between southern Mondulkiri and central Rattanakiri and discuss the possible factors that may have acted as distribution barriers.     

Structure and Evolution of the Mitochondrial Control Region of Leaf Beetles (Coleoptera: Chrysomelidae): A Hierarchical Analysis of Nucleotide Sequence Variation

Abstract To assess the levels of variation at different evolutionary scales in the mitochondrial (mt) control region of leaf beetles, we sequenced and compared the full mt control region in two genera (Chrysomela and Gonioctena), in two species within a genus (Gonioctena olivacea and G. pallida), in individuals from distant populations of these species in Europe, and in individuals from populations separated by moderate (10- to 100-km) to short (<5-km) distances. In all individuals, a highly repetitive section consisting of the tandem repetition of 12 to 17 imperfect copies of a 107- to 159-bp-long core sequence was observed. This repetitive fragment accounts for roughly 50% of the full control-region length. The sequence variability among repeated elements within the control region of a given individual depends on the species considered: the variability within any G. olivacea individual is much higher than that within G. pallida individuals. Comparisons of the repeated elements, in a phylogenetic framework, within and among individuals of G. olivacea and G. pallida suggests that the repetitive section of the control region experienced recurrent duplications/deletions, leading to some degree of concerted evolution. Comparisons between Chrysomela and Gonioctena control regions revealed virtually no significant sequence similarity, except for two long stretches of A's and several [T(T)A(A)] repeats, all found in the control region of other insect orders. Our analyses allowed us to identify portions of the control region with enough variation for population genetic or phylogeographic studies.     

Geographic variation and divergence of songs in the Olive Sparrow species complex

Phenotypic traits such as songs are important in species recognition. Variation in acoustic traits can form barriers to gene flow and promote speciation. Therefore, understanding song divergence is crucial in groups with controversial taxonomy such as Olive Sparrows (Arremonops rufivirgatus), a widespread Neotropical species of songbird with multiple allopatric populations. Taxonomic authorities disagree on the number of Olive Sparrow subspecies, placing them into either two or three main groups. These groups may represent separate species based on morphological traits, but trait divergence within the complex has not been examined. We studied geographic variation in the characteristics of the songs of Olive Sparrows at two geographical levels: among three proposed groups and among five allopatric populations. In a second analysis, we evaluated the strength of acoustic divergence within the complex by comparing acoustic distances among groups and allopatric populations of Olive Sparrows with the acoustic distance among three recognized species in the genus Arremonops. We analyzed 802 songs from 174 individuals across 81 locations and measured 12 variables to describe the fine structural characteristics of the songs of Olive Sparrows, Green-backed Sparrows (A. chloronotus), Black-striped Sparrows (A. conirostris), and Tocuyo Sparrows (A. tocuyensis). We found significant acoustic variation in the Olive Sparrow complex at both geographical levels. Our divergence analysis also revealed that vocal divergence within the complex is similar to or greater than that found between recognized species in the genus. Together, these results suggest that acoustic diversity within the Olive Sparrow complex probably originated by isolation in tandem with selective and/or non-selective factors.     

Temperature Effects on the Temporal Properties of Calling Songs in the Crickets <Emphasis Type="Italic">Gryllus fultoni</Emphasis> and <Emphasis Type="Italic">G. vernalis</Emphasis>: Implications for Reproductive Isolation in Sympatric Populations

Two closely related wood-cricket species, Gryllus fultoni (Orthoptera: Gryllidae) and G. vernalis, produce similar calling songs, consisting of 3-pulse chirps. Analysis of field and laboratory recordings of calling songs showed that, after correction to a common temperature, there was a divergence in chirp and pulse rates between far allopatric populations of G. fultoni and populations sympatric with G. vernalis. To determine whether the divergence in calling songs potentially provides reproductive isolation between G. fultoni and G. vernalis throughout the temperature range over which these insects sing, we recorded calling songs of lab-reared G. fultoni and G. vernalis populations between 18 and 28°C. Mean chirp rate significantly differed between sympatric and far allopatric G. fultoni populations as well as between sympatric G. fultoni and G. vernalis populations. Although there was a significant difference in mean pulse rate between sympatric G. fultoni and G. vernalis populations, pulse rate did not differ between sympatric and far allopatric G. fultoni populations in the laboratory study. Considering the magnitudes of differences in calling song characters discriminated by females of G. fultoni and the mean differences and the variability in calling song characters between the two species, the joint difference in chirp and pulse rates may be adequate for species discrimination over most of the range at which these crickets breed.     

Some Aspects of the Nesting Behavior and Reproductive Biology of Sea Turtles

Basic reproductive data from 21 green turtle (Chelonia mydas),8 leatherback (Dermochelys coriacea), 7 hawksbill (Eretmochelysimbricata), 7 olive ridley (Lepidochelys olivacea),6 loggerhead(Caretta caretta), 1 Kemp's ridley (Lepidochelys kempi), and1 flatback (Chelonia depressa) populations are provided. Someintraspecific and interspecific relationships between size ofnester and clutch, egg size and hatchling size are analyzed.Measurements of reproductive rates (=numbers of hatchlings perfemale per year) in 11 populations varied from 35 to 200 inan olive ridley and loggerhead colony, respectively. Nestingbehavior of each species is described in terms of type of nestingemergence and time spent on the nesting beach (=chelonery).The relatively large number of yolkless eggs laid by many leatherbacksand by some hawksbills invites further study. Some aspects ofsea turtle nesting behavior and reproduction are compared tothose of other chelonians.     

Tetranucleotide markers from the loggerhead sea turtle (Caretta caretta) and their cross-amplification in other marine turtle species

The loggerhead sea turtle (Caretta caretta) is a federally threatened species and listed as endangered by the World Conservation Union (IUCN). We describe primers and polymerase chain reaction (PCR) conditions to amplify 11 novel tetranucleotide microsatellite loci from the loggerhead sea turtle. We tested primers using samples from 22 females that nested at Melbourne Beach, Florida (USA). Primer pairs yielded an average of 11.2 alleles per locus (range of 4–24), an average observed heterozygosity of 0.83 (range 0.59–0.96), and an average polymorphic information content of 0.80 (range 0.62–0.94). We also demonstrate the utility of these primers, in addition to primers for 15 loci previously described, for amplifying microsatellite loci in four additional species representing the two extant marine turtle families: olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata), green turtle (Chelonia mydas), and leatherback (Dermochelys coriacea).     

Termites and the turnover of dead wood in an arid tropical environment

Summary The role of sunbirds (Nectariniidae) in the pollination ecology of Strelitzia nicolai (Musaceae) was studied for one year in a coastal dune forest in Zululand, South Africa. It was found that S. nicolai produced large quantities of low quality nectar (1.74 j/l); that nectar production was highest during the day-time; and that the flowers displayed several characteristics attractive to bird-visitors. The flowers were large, conspicuous and provided the birds with a perch, facilitating easy access to the nectar. Flowers were visited by four species of sunbirds: Olive Sunbird Nectarinia olivacea, Grey Sunbird N. veroxii, Black Sunbird N. amethystina, and Collared Sunbird Anthreptes collaris. Sunbirds visited the flowers throughout the year, and apparently cued into changes in the flower angle as an indication of nectar flow rates. Sunbirds perched on the flowers in a manner which effected pollination, the pollen being transferred to the stigma via the birds' feet. Besides the sunbirds, there were other visitors (bushbabies, monkeys and insects) to the flowers, but they did not visit the flowers frequently nor did they appear to be significant pollinators. The high seed set of S. nicolai in the study area attests to the efficacy of the sunbirds as pollinators.     

Evidence of olive ridley mitochondrial genome introgression into loggerhead turtle rookeries of Sergipe, Brazil

The coastline of Sergipe state hosts the main Brazilian nesting sites of Lepidochelys olivacea (Eschscholtz, 1829). The second most abundant species of turtles in Sergipe is Caretta caretta (Linnaeus, 1758). Both sea turtle species, respectively known as olive ridley and loggerhead, are currently listed as endangered by the International Union for the Conservation of Nature and Natural Resources. The genetic diversity of the Sergipe loggerhead population (N = 51) was assayed by analyzing 627 bp from the control region of mitochondrial DNA in nesting females. Three haplotypes were identified: CC-A4, CC-A24 and CC × LO. The last one was recorded for specimens considered hybrids because they represent L. olivacea’s mtDNA, but had the external morphology of C. caretta or of a mixture of both species. Based on the two types of hybrids, it was hypothesized that at least two hybridization events had occurred: a more ancient hybridization event, accompanied by introgression (F2 or later backcrosses), and a recent one (F1), both of which involving the same L. olivacea haplotype. The incidence of L. olivacea mitochondrial genome introgression into the C. caretta rookeries was only observed in Sergipe, which could be related to the large numbers of L. olivacea in this region and an overlap of reproduction periods and distribution areas of both species. This may also be associated to global warming since it might alter the sex ratio of sea turtles, thus facilitating interspecific mating. Awareness of gene flow between these species will significantly influence the development and implementation of adequate management strategies.     

Bioko: critically important nesting habitat for sea turtles of West Africa

We evaluate the conservation status and threats faced by sea turtle nesting populations at Bioko Island, Equatorial Guinea (Central Africa). Beaches were monitored to obtain a detailed sea turtle nest census and, where possible, tagging of adult females was undertaken. Four sea turtle species were found nesting in the area: the green turtle (Chelonia mydas), the leatherback (Dermochelys coriacea), the olive ridley (Lepidochelys olivacea) and the hawksbill (Eretmochelys imbricata); with the former two species nesting in regionally important numbers. Nesting activity was concentrated between November and February, with a peak in December–January. Tagging and recapture of green turtles in two consecutive seasons suggested an estimated 560 (interquartile range: 420–1,681) and 414 (interquartile range: 190–1,255) nesting females in the area, respectively. Estimated numbers of nesting leatherbacks ranged from 123 to 215 and 243 to 293 in the first and second season, respectively. The other two species were less abundant (olive ridley: 19–29 and 28–43; hawksbill: 4–10 and 2 turtles). Data were compared with more recent surveys in the area and contextualised with information on human related threats. Despite the size of nesting stocks, ongoing permitted and illegal take of adult turtles at the nesting site constitutes a serious threat for these breeding aggregations. Additionally, tag returns from throughout the Gulf of Guinea suggest that the level of take in regional fisheries may also be a major threat.     

Nuclear markers reveal a complex introgression pattern among marine turtle species on the Brazilian coast

Surprisingly, a high frequency of interspecific sea turtle hybrids has been previously recorded in a nesting site along a short stretch of the Brazilian coast. Mitochondrial DNA data indicated that as much as 43% of the females identified as Eretmochelys imbricata are hybrids in this area (Bahia State of Brazil). It is a remarkable find, because most of the nesting sites surveyed worldwide, including some in northern Brazil, presents no hybrids, and rare Caribbean sites present no more than 2% of hybrids. Thus, a detailed understanding of the hybridization process is needed to evaluate natural or anthropogenic causes of this regional phenomenon in Brazil, which could be an important factor affecting the conservation of this population. We analysed a set of 12 nuclear markers to investigate the pattern of hybridization involving three species of sea turtles: hawksbill (E. imbricata), loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea). Our data indicate that most of the individuals in the crossings L. olivacea × E. imbricata and L. olivacea × C. caretta are F1 hybrids, whereas C. caretta × E. imbricata crossings present F1 and backcrosses with both parental species. In addition, the C. caretta × E. imbricata hybridization seems to be gender and species biased, and we also found one individual with evidence of multispecies hybridization among C. caretta × E. imbricata × Chelonia mydas. The overall results also indicate that hybridization in this area is a recent phenomenon, spanning at least two generations or ～40 years.     

Divergence in mating signals correlates with genetic distance and behavioural responses to playback

Animals use acoustic signals to defend resources against rivals and attract breeding partners. As with many biological traits, acoustic signals may reflect ancestry; closely related species often produce more similar signals than do distantly related species. Whether this similarity in acoustic signals is biologically relevant to animals is poorly understood. We conducted a playback experiment to measure the physical and vocal responses of male songbirds to the songs of both conspecific and allopatric‐congeneric animals that varied in their acoustic and genetic similarity. Our subjects were territorial males of four species of neotropical Troglodytes wrens: Brown‐throated Wrens (Troglodytes brunneicollis), Cozumel Wrens (T. beani), Clarion Wrens (T. tanneri) and Socorro Wrens (T. sissonii). Our results indicate that birds respond to playback of both conspecific and allopatric‐congeneric animals; that acoustic differences increase with genetic distance; and that genetic divergence predicts the strength of behavioural responses to playback, after removing the effects of acoustic similarity between subjects’ songs and playback stimuli. Collectively, these results demonstrate that the most distantly related species have the most divergent songs; that male wrens perceive divergence in fine structural characteristics of songs; and that perceptual differences between species reflect evolutionary history. This study offers novel insight into the importance of acoustic divergence of learned signals and receiver responses in species recognition.     

Song frequency correlates with latitude and individual body size in the cicada <Emphasis Type="Italic">Mogannia formosana</Emphasis> Matsumura (Hemiptera: Cicadidae)

Analyses of acoustic variation between and within populations can help to clarify the evolution and diversification of cicada calling songs. In this study, we analyzed the acoustic variation in the calling song of Mogannia formosana within Taiwan and between Taiwan and Green Island to assess the effects of geographic locations. Furthermore, chorusing males in the Green Island population were recorded and collected from the same habitat site during the same time period to investigate the relationship between individual body size and the acoustic features of calling songs. Among populations of M. formosana, we found that most of the acoustic variation in M. formosana calling songs was associated with frequency parameters, in which six frequency parameters changed significantly with latitude on the island of Taiwan. In contrast, temporal parameters, which were associated with principal components corresponding to less acoustic variation than that of the first principal component, were also found to be significant among populations but did not show consistent trends of difference with latitude. However, the geographically isolated Green Island population exhibited the lowest number of short echemes in segment B, which is the diagnostic structure employed to separate M. formosana from other M. species. This finding suggests that the temporal pattern of segment B in the calling songs of M. formosana might be important for both population differentiation and interspecific recognition. In a chorus of the Green Island population, the sound frequency of the last short echeme was found to be significantly correlated with individual body size. The possible role played by sexual selection in shaping sound frequency as a result of its reliable association with body size was discussed. We suggest that, in comparison with temporal elements, the frequency elements of segment B in calling songs of M. formosana in chorus can serve as a more reliable indicator of body size for female mate choice.     

SONG MIMICRY AND SPECIES STATUS OF THE GREEN WIDOWFINCH VIDUA CODRINGTONI

Summary

Payne, R. B., Payne, L. L. &; Nhlane, M. E. D. 1992. Song mimicry and species status of the Green Widowfinch Vidua codringtoni. Ostrich 63:86-97.

The Green Widowfinch Vidua codringtoni mimics the songs of the Redthroated Twinspot Hypargos niveoguttatus, its apparent foster species, in Zimbabwe, Zambia and Mala?i. Of 38 male Green Widowfinches, 37 mimicked the twinspot; one mimicked a firefinch and not the twinspot. A wild-captured juvenile developed mimicry of twinspot song after six months and retained its mimicry through the next year. Male Green Widowfinches have glossy breeding plumage (green to blue), black wings, white bill and bright orange feet, a colour combination unlike other widowfinches in their range in southern Africa. Females are marginally distinguishable from other widowfinch species. Green Widowfinches occur together locally with Black V. funerea nigerrima, Purple V. purpurascens and Steelblue V. chalybeata Widowfinches and do not interbreed with them. The four species of widowfinches in southern Africa each have distributional ranges within the limits of their foster species.     

Comparison of the mating behaviour between two sympatric species,Nezara antennata andN. viridula (Heteroptera: Pentatomidae), with special reference to sound emission

Mating behaviour and associated songs were compared between 2 sympatric congeneric species,Nezara antennata andN. viridula, between which interspecific mating was known to occur under natural conditions. The fundamental sequence of mating behaviour for these species was the same. Three kinds of songs were recorded from each sex ofN. antennata. ForN. viridula, 4 kinds of male songs and 3 kinds of female songs were recorded. The songs which corresponded with definite behavioural bouts were distinct between these species. Some consideration was made as to why interspecific differences in the songs did not sufficiently engender ethological isolation. In addition, some geographic variations in the songs were shown among Yugoslavian (Čokl et al. 1972), American (Harris et al. 1982) and Japanese populations ofN. viridula. These variations were relatively inconspicuous when compared with the interspecific differences fromN. antennata.     

Differentiation of Mating Vocalizations in Birds: Acoustic Features in Mainland and Island Populations and Evidence of Habitat-Dependent Selection on Songs

Local environments can act as selective agents on some characteristics of birds’ songs, whereas other song traits may not reflect local genetic adaptation. Geographic variation in songs of two Australian bird species (red‐capped robins Petroica goodenovii, western gerygones Gerygone fusca) was studied to examine one component of the ‘habitat‐dependent selection’ hypothesis. This hypothesis suggests that: (1) the detailed spectral characteristics of male songs are an evolved response to local habitat conditions affecting signal propagation and detection and (2) parallel evolution of other fitness traits sets up the potential for assortative mating by female choice. To examine the first part of the hypothesis, I made comparisons among widespread mainland populations and an island population using two levels of analysis: a typological analysis of song morphology (phonology: notes, syllables, syntax, temporal pattern, repertoires) and a spectral analysis of acoustic characteristics of songs (mean frequency, Wiener entropy, frequency modulation) using an automated procedure of feature extraction (Sound Analysis Pro). Spectral analysis was also used to extract values of the same acoustic features from the background sound environment of each recorded population. The typological analysis revealed no differences among mainland populations of either species, but large differences between mainland songs and those on the island. In contrast, the spectral analysis revealed acoustic divergence among populations, both mainland and island. For both species, Wiener entropy of songs correlated negatively with that of the ambient sound environment, consistent with predictions of the habitat‐dependent selection hypothesis of environmental selection on signal design.     

Entre Ríos Seedeater (Sporophila zelichi): a species that never was

ABSTRACT Entre Ríos Seedeaters (Sporophila zelichi), also called Zelich's Seedeaters, White‐collared Seedeaters, and Narosky's Seedeaters, are one of the rarest birds in the Neotropics. However, doubts have been raised about the validity of this species. Therefore, I evaluated the systematic status of Entre Ríos Seedeaters based on analysis of previously unpublished vocal and habitat data. I tested four hypotheses regarding the systematic status of S. zelichi: Good Species Hypothesis (valid species), Hybridization Hypothesis (hybrid S. palustris×S. cinnamomea), Color Morph Hypothesis I (morph of S. cinnamomea), and Color Morph Hypothesis II (morph of S. palustris). The songs and preferred habitat of S. zelichi are indistinguishable from those of Marsh Seedeaters (S. palustris), and the songs of both forms have exhibited similar changes from the early 1990s to 2003–2007. In contrast, the songs and preferred habitat of Chestnut Seedeaters (S. cinnamomea) differ from those of S. zelichi. Therefore, the Good Species Hypothesis is rejected by vocalization and habitat data, the Hybrid Hypothesis is undermined by the absence of shared vocal characters and limited habitat overlap of the proposed parental forms S. cinnamomea/S. palustris, and Color Morph Hypothesis I is rejected by both song and habitat data. However, Color Morph Hypothesis II is supported by both song and habitat data. Thus, I propose that S. zelichi be considered a color morph of S. palustris.     

THE INFLUENCE OF THE ENVIRONMENT ON BREEDING SUCCESS OF A SUBURBAN POPULATION OF CRESTED BARBETS TRACHYPHONUS VAILLANTII

Van Zyl, A.J. 1994. The influence of the environment on the breeding success of a suburban population of Crested Barbets Trachyphonus vaillantii. Ostrich 65: 291–296.

I studied the breeding biology of the Crested Barbet Trachyphonus vaillantii in Colbyn, a suburb east of Pretoria, South Africa, for nine breeding seasons from 1981 to 1989 to examine patterns in annual breeding success, breeding attempt success in multiple broods, and rainfall. The modal incubation period was 14 days and the nestling period ranged from 28 to 31 days. Average clutch size for all the years was 3,3 eggs/clutch and there was no significant difference in clutch size or number of young fledged/nest between years. On average, Crested Barbet pairs made 2,4 breeding attempts/season. There was no difference in clutch size or breeding success between the breeding attempts. Crested Barbets nesting in natural nests laid on average larger clutches than those in artificial nestboxes, but had non-signficantly lower breeding success. Failure to raise Crested Barbet chicks was attributed to parasitism by Lesser Honeyguides Indicator minor, bee swarms occupying nestboxes, and flooding of natural nests. Breeding performance was not correlated with rainfall or adult body size. The suburban environment may be less variable than a natural environment, resulting in a stable breeding Crested Barbet population.     

Song structure variability in passerine birds: Random variation or direct informative changes

The variability of the fine song structure was studied in the wood warbler (Phylloscopus sibilatrix), willow warbler (Ph. trochilus), greenish warbler (Ph. throchiloides viridanus), chaffinch (Fringilla coelebs), and gray shrike thrush (Colluricincla harmonica). The increase in the number of similar elements per phrase is shown to be related to the conspecific and heterospecific male-male song interactions in these birds. The responses of wood warbler males to playback conspecific songs with standard and prolonged (in the number of similar elements) second phrases differ significantly. The initial phrases of willow warbler songs become significantly longer in the populations with a high density as compared to those in populations of low density. The increase in the variability of both phrase combinations and song duration is shown to be related also to the song interaction with conspecific males for the willow warbler, greenish warbler, chaffinch, and gray shrike thrush. The within-song type variations turned out to play an important role during male-male interactions of different species. The results obtained suggest that similar ways of song responses may be quite widespread among passerine birds and reflect the general principles of changes in the song structure during acoustic interactions.