Zonotrichia Albicollis Research Articles

Prior residence has a gradual influence on dominance in captive white-throated sparrows

Abstract. To investigate the influence of prior residence on dominance in captive white-throated sparrows, Zonotrichia albicollis, 28 groups of six birds each were studied in outdoor aviaries during winter. After periods of prior residence ranging from 2 to 45 days, the three highest-ranking birds in each of two aviaries were placed together in one of the aviaries and the three lowest-ranking birds from each aviary were placed together in the other aviary. The influence of prior residence increased gradually over at least 2 weeks to an asymptote at which individuals with the advantage of prior residence dominated newcomers in approximately 90% of the cases. In the initial groupings of unfamiliar birds, when only intrinsic features of individuals influenced dominance, only size (as indicated by wing length) correlated with dominance. The gradual increase in dominance of residents over newcomers suggests that prior residence is not used for conventional settlement of disputes. This influence of prior residence on dominance provides a mechanism for the tendency of an individual white-throated sparrow in the field to dominate more opponents at the centre of its range than at the edge.

The spatial extent and relative influence of landscape-level factors on wintering bird populations

The influences of the landscape matrix (complex of habitats surrounding a study plot) and within-patch vegetation were studied in bird communities wintering in the piedmont of Georgia, USA. Variation at the landscape and within-patch levels was controlled to reduce the likelihood of confounding and spurious relationships. The landscape matrix within 500 m of each study plot was quantified from aerial photographs. Statistical models using landscape matrix and within-patch vegetation variables explained 73–84% of variation in bird abundance and diversity among sites with landscape matrix variables accounting for 30–90% of the variation. Variation in bird species richness and diversity was explained solely by landscape variables. Models for individual species such as Carolina Wrens (Thyrothorus ludovicianus) and Rufous-sided Towhees (Pipilo erythrophthalmus) had r2 > 0.80, with the landscape matrix variables accounting for the majority of this variation. However, other species like Northern Cardinals (Cardinalis cardinalis) and White-throated Sparrows (Zonotrichia albicollis) were most strongly influenced by within-plot vegetation. The landscape influence extended beyond habitats immediately adjacent to the study plots as indicated by significant variables describing variation in more distant habitat patches. These analyses illustrate a technique for comparing the strength of within-patch versus landscape influences and measuring the spatial extent of the landscape influence in fine-grained landscapes. Report No. 3955, Environmental Sciences Division, Oak Ridge National Laboratory.

Postfledging parental care in the White-throated Sparrow (Zonotrichia albicollis)

We studied parental care in White-throated Sparrows (Zonotrichia albicollis) during the last 4 days of the nestling period and the first 4 days of the fledgling period. Both parents made more provisioning trips and delivered more food to fledglings than to nestlings. Though male and female parents provided nestlings with equal amounts of food, female parents provided fledglings with more food than did male parents. Fledglings received fewer items per trip than did nestlings. This suggests that fledging was associated with a change in parental foraging strategies. Postfledging parental care did not differ between broods from late nests and broods that were to be followed by a second nesting attempt.

Effects of fenitrothion on survival, behavior, and brain cholinesterase activity of white-throated sparrows (Zonotrichia albicollis)

White-throated sparrows (Zonotrichia albicollis) were fed six concentrations of dietary fenitrothion (0, 25, 40, 60, 90, and 200 ppm) for 5 d to determine effects on survival, behavior, and brain cholinesterase (ChE) activity. Each bird was observed for 5 min/d for 5 d before, during, and 3 d after exposure, and activities were categorized. Brain ChE activity of birds dying during exposure and of birds surviving 3 d after exposure was measured. The 5-d LC50 was 49.8 ppm, with 100% mortality occurring in the 90- and 200-ppm groups. All birds dying during the exposure period had brain ChE activities depressed more than 2 sd below control activity, and level of inhibition was positively related to dietary concentration (p = 0.04). ChE activities of birds surviving exposure were inhibited from 41 to 58% of control activity. The 25-, 40-, 60-, and 90-ppm groups increased time spent foraging during the exposure period over pretreatment rates, whereas the 200-ppm group showed a decrease. Birds that died during the 5-d treatment period weighed 30% less than survivors. There was also a trend for decreased time spent hopping in all fenitrothion-treated groups. Frequency of singing declined in all groups, including controls, throughout the exposure period and increased slightly during the recovery period. Fenitrothion residues available to birds in spruce bud-worm larvae were only 0.7 to 1.2 ppm wet weight 3 h after aerial application at 210 g active ingredient per hectare.

Aggressive Performance as a Behavioral Correlate of Plumage Polymorphism in the White-Throated Sparrow (Zonotrichia Albicollis)

Abstract Morph and sex-specific differences in aggressive performance were examined in the white-throated sparrow. Among the four morph/sex classes, white-striped males had the strongest response to white-striped models and were the most likely to approach and attend song playbacks independently. The slightly weaker responses of tan-striped males and white-striped females were similar to each other. Tan-striped females were the least aggressive. Aggression by white-striped females enabled tan-striped male x white-striped female pairs to perform as well, or better, than white-striped male x tan-striped female pairs. Tan-striped males paired earlier than white-striped males. An increased prevalence of territorial tan-striped males corresponded to the arrival of females on the breeding grounds. The data are consistent with the hypothesis that negative assortative mating benefits tan-striped males through the supplemental aggression of white-striped females. However, the apparent preference of white-striped females for tan-striped males suggests that there are benefits to negative asortative mating other than those that might arise from differences in aggressive performance.

Singing in Relation To Social Dominance and Testosterone in White-Throated Sparrows

Abstract Singing by white-throated sparrows Zonotrichia albicollis during the winter in natural situations occurred most frequently among birds with high rank in a dominance hierarchy. Genetic morph, age and sex had no significant influence on singing during winter. Among testosterone-implanted birds in small groups in large aviaries, dominance rank strongly influenced singing. Testosterone-treated birds with top rank sang most frequently, those with second rank less, and those with lower rank never. As a testosterone-treated bird's rank changed in the course of regroupings with new opponents, its frequency of singing also changed. Dominance in a group thus interacted with testosterone to promote singing. In addition, grouped birds in May before treatment with testosterone did not sing. As a consequence, it seems likely that the normal seasonal development of territorial behavior and singing involves cascading interactions of endocrine states and social circumstances.

The White-Throated Sparrow That Stayed

The White-Throated Sparrow That Stayed

Temporal Relationships in White-Throated Sparrow Song

Bird song has been likened to human music for centuries (e.g., Anonymous 1717, Hartshorne 1973). The analogy between bird song and music is perpetrated to some degree by the use of musical terms to describe avian vocalizations: individual sound elements are called and strings of notes are called songs. In most modern studies of song this analogy has fallen out of favor (e.g., Dobson and Lemon 1977). However, recent studies have shown that fixed relationships between the frequencies of adjacent notes, a defining feature of human music, occur in the songs of several species, and the birds seem to use this feature to recognize their songs (e.g., see Weary et al. 1991). The aim of the present study was to determine if there are other predictable relationships between notes. In particular we investigated whether the duration of song notes sung by White-throated Sparrows (Zonotrichia albicollis) are correlated. When an individual produces a relatively long first note, do the subsequent notes tend to be longer? These temporal relationships between notes are termed rhythm when describing music. The familiar tune is still recognized when it is sped up or slowed down (changes in tempo), because the temporal relationships between the notes (and internote intervals) are maintained. The only formal study of rhythm perception in nonhuman animals was done in the laboratory on European Starlings (Sturnus vulgaris) (Hulse et al. 1984). This study showed that birds can learn to discriminate rhythmic from arrhythmic sound patterns, and can generalize this discrimination over changes in tempo. How important are the temporal relationships among sounds in nature? For birds, there is some evidence that these relationshipsare important. Becker's (1982) review pointed to several temporal features of song that are important in species recognition. For example, the manipulation of the intervals between notes in a song affects recognition in several species, including White-throated Sparrows (Falls 1963). Also, interspecific comparisons have demonstrated that birds which sing longer songs also tend to use greater intervals to separate them (Dobson and Lemon 1975, Weary and Lemon 1988). Thus, certain aspects of timing do seem important in bird song. Other evidence is harder to interpret. For example, Lambrechts and Dhondt (1987) found that during the course ofa song, Great Tits (Parus major) tend to sing with progressively longer intervals between notes. The rhythmic aspect of this behavior is that when Great Tits produce longer inter-note intervals, they also produce longer inter-phrase intervals (phrases consist of groups of notes). The arrhythmic aspect is that there is no corresponding increase in the duration of the notes themselves. Thus, in one respect Great Tits maintain rhythm over a change in tempo, but in another they do not.

Song Sparrows Learn from Limited Exposure to Song Models

BORROR, D. J., AND W. W. H. GUiN. 1965. Variation in White-throated Sparrow songs. Auk 82:26-47. DossON, C. W., AND R. E. LEMON. 1975. Re-examination of the monotony-threshold hypothesis in bird song. Nature, Lond. 257:126-128. DossON, C. W., AND R. E. LEMON. 1977. Bird song as music. J. Acoust. Soc. Am. 61:888-890. DOOLING, R. J. 1982. Auditory perception in birds, p. 95-177. In D. E. Kroodsma and E. H. Miller [eds.], Acoustic communication in birds. Vol. 1. Academic Press, New York. FALLS, J. B. 1963. Properties of birdsong eliciting responses from territorial males. Proc. Int. Omrnithol. Congr. 13:259-271. HARTSHORNE, C. 1973. Born to sing. Indiana University, Bloomington, IN. HULSE, S. H., J. HUMPAL, AND J. CYNX. 1984. Discrimination and generalization of rhythmic and arrhythmic sound patterns by European Starlings (Sturnus vulgaris). Music Percep. 1:442-464. HURLY, T. A., R. G. WEISMAN, L. RATCLIFFE, AND I. JOHNSRUDE. 1991. Absolute and relative pitch production in the song of the White-throated Sparrow (Zonotrichia albicollis). Bioacoustics 3:81-91. LAMBRECHTS, M., AND A. DHONDT. 1987. Differences in singing performance between male Great Tits. Ardea 75: 43-52. NELSON, D. A. 1988. Feature weighting in speciessong recognition by the Field Sparrow, Spizella pusilla. Behaviour, 106: 158-182. WEARY, D. M. 1990. Categorization of song notes in Great Tits: which acoustic features are used and why? Anim. Behav. 39:450-457. WEARY, D. M., AND R. E. LEMON. 1988. Evidence against the continuity-versatility relationship in bird song. Anim. Behav. 36:1379-1383. WEARY, D. M., R. G. WEISMAN, R. E. LEMON, T. CHIN, AND J. MONGRAIN. 1991. Veeries use frequency ratio to sing and recognize songs. Auk 108:977981.

Songs of Two Mexican Populations of the Western Flycatcher Empidonax difficilis Complex

HURLY, T. A., L. RATCLIFFE, D. M. WEARY, AND R. WEISMAN. In press. White-throated Sparrows (Zonotrichia albicollis) can perceive pitch change using frequency ratio independent of frequency difference. J. Comp. Psych. MARLER, P. 1960. Bird songs and mate selection, p. 348-367. In W. E. Lanyon and W. N. Tavolga [eds.], Animal sounds and communication. American Institute of Biological Sciences, Washington, DC. NELSON, D. A. 1989. The importance of invariant and distinctive features in species recognition of bird song. Condor 91:120-130. RICE, W. R. 1989. Analyzing tables of statistical tests. Evolution 43:223-225. RICHARDS, D. G. 1981. Estimation of distance of singing conspecifics by the Carolina Wren. Auk 98:127-133. SHACKLETON, S. A. 1991. Singing behaviour of Black-capped Chickadees (Parus atricapillus). M.S .thesis, Queen's University, Kingston, Ontario, Canada. WEARY, D. M., R. G. WEISMAN, R. E. LEMON, T. CHIN, AND J. MONGRAIN. 1991. Use of the relative frequency of notes by Veeries in song recognition and production. Auk 108:977-981. WEISMAN, R., AND L. RATCIFFE. 1989. Absolute and relative pitch processing in Black-capped Chickadees, Parus atricapillus. Anim. Behav. 38:685692. WEISMAN, R., L. RATCLIFFE, I. JOHNSRUDE, AND T. A. HURLY. 1990. Absolute and relative pitch production in the song of the Black-capped Chickadee. Condor 92:118-124.

Relative Frequency Parameters and Song Recognition in Black-Capped Chickadees

Marler (1960) proposed that those features of bird song which are least variable should be most important for species recognition (termed the invariant features hypothesis). This hypothesis has been tested on several species of song birds, with mixed results. For example, Field Sparrows (Spizella pusilla) and Chipping Sparrows (S. passerina) do not use least variable features to classify conspecific song (Nelson 1989). On other hand, Veeries (Catharus fuscescens) and White-throated Sparrows (Zonotrichia albicollis) do use features with very little variation to recognize conspecific song. Altering normally stereotypic between-note frequency ratios in these species' songs reduces amount of aggressive response to playback (Weary et al. 1991, Hurly et al. 1990). Similarly, Chiffchaffs (Phylloscopus collybita) and Firecrests (Regulus ignicapillus) respond less strongly to playback of songs where within-note frequency sweeps have been altered (Becker 1982). Black-capped Chickadee (Parus atricapillus) song consists of two pure tonal notes: (see NORM in Fig. 1). Frequency descends during fee note (termed glissando), and there is a drop in frequency between fee and bee (termed pitch interval; Weisman et al. 1990). The frequency ratio of glissando (fee-start/fee-end), and ratio of pitch interval (fee-end/bee) are highly stereotypic, varying by less than two percent among and within birds in populations from Alberta, Wisconsin and Ontario (Weisman et al. 1990). The frequency at any given point within a song is highly predictable from any other point, that is, highly correlated to all other points. Although chickadees shift their songs over a wide range of absolute frequencies (Shackleton 1991), glissando and pitch interval remain constant. Playback studies conducted in laboratory showed that adult male Blackcapped Chickadees respond less aggressively to songs where pitch interval (fee-end/bee) had been altered, compared to normal songs (Weisman and Ratcliffe 1989). Therefore, to examine importance of glissando (fee-start/fee-end) to song recognition in this species, we played back songs to wild males in which we altered both of these relative frequency parameters. METHODS

Timing of Cranial Pneumatization in White-Throated Sparrows

To assess correlates of the timing of cranial pneumatization in wintering Whitethroated Sparrows (Zonotrichia albicollis), we repeatedly determined the stage of pneumatization of marked individuals in the field following autumnal migration. There were pronounced differences among individuals and among years in the timing of cranial pneumatization. Pneumatization occurred later in larger individuals, as indicated by wing length, but the timing of pneumatization was not related to dates of arrival in wintering areas nor to social dominance.

White-throated sparrows (Zonotrichia albicollis) can perceive pitch change in conspecific song by using the frequency ratio independent of the frequency difference.

In the ascending songs of white-throated sparrows (Zonotrichia albicollis), the first note (Phrase 1) is sung lower than the remaining notes (Phrase 2). The production of this frequency change is more reliably predicted by the frequency ratio (Phrase 2 - Phrase 1) than by the frequency difference (Phrase 2 - Phrase 1). To determine whether sparrows use the ratio rather than the difference to identify ascending songs, we transposed a low-frequency song upward in frequency, maintaining a normal frequency difference but altering the frequency ratio, and we transposed a high-frequency song downward in the same way

White-throated sparrows (Zonotrichia albicollis) can perceive pitch change in conspecific song by using the frequency ratio independent of the frequency difference.

White-throated sparrows (Zonotrichia albicollis) can perceive pitch change in conspecific song by using the frequency ratio independent of the frequency difference.

Comparing Actual and Random Distributions of Nearest Neighbors

Pearson (1991) watched (Spizella pusilla) and White-throated (Zonotrichia albicollis) feeding on artificial patches of three sizes. He compared the observed distributions of distances between nearest neighbors in small groups with computer-generated expected distributions. Two principal results were given (presented here in reverse order from Pearson's paper). First, both species occurred disproportionately often on portions of the patches near a nearby pile. Pearson concluded the birds were attracted to Second, observed distributions of distances between birds differed from Monte Carlo (computer-generated) distributions and differed between the two species for most combinations of group size and patch size. The Monte Carlo method was complete spatial randomness (CSR; Diggle 1983: 4), presumably accomplished by generating a pseudorandom X-value and Y-value for each point. The points were constrained only to be at least 1 cm apart; 1,000 nearest-neighbor distances were generated for each group size in this manner. Pearson's (1991) conclusions were derived from differences between the spacing of real and Monte Carlo-generated birds, although he stated that spacing behavior could not be separated from these birds' affinity for cover. The conclusions are valid only to the extent that CSR represents a realistic expectation of the birds' behavior in the absence of social interactions. However, because the birds were attracted to the pile, we know that they did not conform to CSR. In the absence of social interactions, one would expect nearest-neighbor distances on average to be less than those predicted by the purely random model, because the birds were bunched at one end. Fortunately, Pearson's (1991) detailed data allow construction of a more suitable alternative model. Values for X are computed pseudorandomly, as in Pearson's study. Values for Y are computed by using a weighted pseudorandom number generator (Robertson 1977), based on the known distributions in Pearson's figures 4 and 5. The weighted values cast birds on the plane with a preference for proximity to a brush pile at Y of zero; for instance, they place 72% of the computer-generated Field Sparrows within the closest 5 cm of a small patch when group size is two. The alternative model (Fig. 1) differs greatly from Pearson's (1991) figure 1. Although the mean may not be a meaningful measure of central tendency in these distributions, the recalculated means are 0.61 to 0.64 those of Pearson's model. They differ by 3 to 14 cm. Although Pearson's interesting conclusions about differences between spacing behaviors of the two species of sparrows may be unaffected, his conclusions about the degree of randomness in their spacing (Pearson 1991:fig. 3) are not supported by his data when a more realistic distribution of birds is used for comparison. The alternative model for random spacing with a preference for cover (Fig. 1) assumes that the sparrows have no overall preference for certain regions in the X direction, that the six zones described in Pearson (1991) are an accurate description of the birds' use of space, and that positions in X and Y are uncorrelated. Pearson did not test these assumptions, nor can they be tested from the published data. Comparison of the alternative weighted model with observed distributions, though more valid, is probably less powerful than comparison of Pearson's (1991) purely random model. This is because the birds' distribution in the Y direction is determined both by a known preference for Y of zero and by a suspected minimum or preferred distance between birds. Thus, using the observed Y distribution taints the model with an unknown component of social spacing itself. Monte Carlo methods allow testing for spatial patterning when conventional methods fail (Diggle 1983, Krebs 1989, Manly 1991). The technique of using weighted number generators (Larkin 1982) extends Monte Carlo methods to some situations in which distributions in one or more dimensions are not purely random.

Borrelia burgdorferi in Ticks (Acari: Ixodidae) from Coastal Virginia

Ixodid ticks removed from hosts and from vegetation during March-November 1987 at sites in coastal Virginia and North Carolina were examined for Borrelia burgdorferi. B. burgdorferi was evident in nine (22%) Ixodes cookei Packard removed from rice rats (Oryzomys palustris), a white-footed mouse (Peromyscus leucopus), and raccoons (Procyon lotor); four (6%) Amblyomma americanum (L.) removed from raccoons; and two (3%) Dermacentor variabilis (Say) removed from a raccoon and a rice rat. B. burgdorferi was also detected in Ixodes dentatus Marx removed from a brown thrasher (Toxostoma rufum), a Carolina wren (Thryothoros ludovicianus), and a towhee (Piplio erythrophthalamus); and in Haemaphysalis leporispalustris (Packard) removed from a brown thrasher and a white-throated sparrow (Zonotrichia albicollis) netted at Kiptopeke Beach, Va. Two Ixodes dammini Spielman, Clifford, Piesman & Corwin were collected on Parramore Island; one specimen was examined for spirochetes, and it was infected with B. burgdorferi. No spirochetes were detected in host-seeking A. americanum and Amblyomma maculatum Koch removed from vegetation. The plasma of one P. leucopus and sera obtained from two P. lotor contained antibodies to B. burgdorferi. All infected ticks and the seroreactive hosts were collected from the Eastern Shore of Virginia.

An experimental study of brood division in white-throated sparrows

Parental care towards experimentally restrained white-throated sparrow, Zonotrichia albicollis, fledglings was examined for evidence of brood division. Brood division occurred in 14 of 17 broods and was characterized by distinct but overlapping preferences by parents for particular brood members. The combined efforts of the parents usually resulted in an even distribution of resources among the brood. However, in some cases, brood division caused some fledglings to receive more food than others. Within-brood variation in food received was correlated with the difference between parents in parental effort. Brood division was maintained by the location of the young for some parents and by the identity of the young for other parents. It is suggested that changes in brood mobility might necessitate a shift in the cues used to discriminate between fledglings in order for parents to maintain brood division through the post-fledging period.

Song output and stimulation of the female in white-throated sparrows

We investigated the importance of song length and singing rate in stimulating female white-throated sparrows, Zonotrichia albicollis. In November 1988 ten female and one male white-throated sparrow were captured during the fall migration. To enhance the expression of sexual receptivity, the females were implanted with 17-beta-estradiol silastic pellets. Using the visual stimulus of a non-singing male to further enhance the expression of sexual receptivity in the females, we found that females gave a greater response, in the form of copulation displays, to a five-note versus a two-note version of a typical male white-throated sparrow song. Each version was played back at four songs per minute. In May 1990 birds were captured and treated as before, except that the two-note song was played at ten songs per minute and the five-note song at four songs per minute. Therefore, each female heard twenty notes per minute. In the second experiment, the females did not show a statistical difference in response to the two- and five-note song playbacks. We interpret the results of the second experiment as indicating the song rate as well as song length is important in stimulating female white-throated sparrows because increasing the rate of the two-note song brought the response up to the level of response we obtained to the five-note song played at the slower rate. We conclude that in white-throated sparrows, song output is important for female stimulation.

Mitochondrial DNA Variation and the Phylogeny of Zonotrichia

Mitochondrial DNA Variation and the Phylogeny of Zonotrichia

Social Inertia and Hormonal Control of Aggression and Dominance in White-Throated Sparrows

Abstract To investigate the effects of familiarity with opponents on the activation of aggression and dominance by testosterone (T) in white-throated sparrows Zonotrichia albicollis, we studied birds in groups of five or six in outdoor aviaries and in a free-living population. Experiments were conducted between January and April, when plasma levels of endogenous gonadal hormones were low. Previously published experiments (ARCHAWARANON & WILEY, 1988) showed that when subjects were given subcutaneous implants of T, held individually in cages for one week, and then grouped with unfamiliar opponents, they established dominance over controls with empty implants. In contracts, the present study showed that low-ranking birds given subcutaneous implants of T and returned to their original groups and aviaries did not change in dominance rank nor in aggression scores over a period of two weeks. When these birds were regrouped with unfamiliar opponents in new aviaries, their dominance ranks and aggression scores increased. This rise in dominance rankings and aggression scores did not result from any effects of regrouping in the absence of hormonal treatments. The sexes did not differ in their responses to these treatments. In the field, T implants markedly increased some individuals' frequencies of aggression but had little or no effect on dominance relationships. The absence of behavioral changes in stable groupings after hormonal treatment, called social inertia, indicates that birds recognize the relative dominance of previous opponents, at least when encountered in familiar locations. Results from the field experiment thus suggest that white-throated sparrows can recognize at least 20 opponents. Hormonal state has more influence on dominance relationships of strangers than on those of opponents familiar with each other in familiar locations.