Genetic and temporal patterns of multiple parasitism by brown-headed cowbirds (Molothrus ater) on song sparrows (Melospiza melodia)

2003 ◽  
Vol 81 (2) ◽  
pp. 281-286 ◽  
Author(s):  
C M McLaren ◽  
B E Woolfenden ◽  
H L Gibbs ◽  
S G Sealy
Keyword(s):  
Reproductive Success ◽  
High Frequency ◽  
Molothrus Ater ◽  
Host Choice ◽  
Melospiza Melodia ◽  
Song Sparrow ◽  
Brood Parasite ◽  
Host Nest ◽  
Song Sparrows ◽  
Genetic Techniques

Identifying the factors used by an avian brood parasite to select host nests is important in understanding the determinates of individual reproductive success, yet such factors are poorly known for most parasitic species. Insights into these factors may come from understanding the conditions under which female parasites lay more than one egg per host nest (multiple parasitism). Using genetic techniques we examined patterns of multiple parasitism on a preferred host, the song sparrow (Melospiza melodia), to determine some basic patterns of multiple parasitism. Multiple parasitism involved equal frequencies of the same female parasitizing the same nest again and two or more females parasitizing the same nest. The frequency of multiple parasitism increased as the season progressed. We also documented a high frequency of parasitism that was not synchronized with host laying. These laying patterns may be the result of cowbirds "making the best of a bad situation" or of suboptimal host choice by inexperienced, nonselective females.

scholarly journals How do Brown-Headed Cowbirds (Molothrus Ater) CAUSE NEST FAILURES IN SONG SPARROWS (MELOSPIZA MELODIA)? A REMOVAL EXPERIMENT

The Auk ◽  
2003 ◽  
Vol 120 (3) ◽  
pp. 772-783
Author(s):  
James N. M. Smith ◽  
Mary J. Taitt ◽  
Liana Zanette ◽  
Isla H. Myers-Smith
Keyword(s):  
Clutch Size ◽  
Breeding Season ◽  
Molothrus Ater ◽  
Melospiza Melodia ◽  
Removal Experiment ◽  
Song Sparrow ◽  
Failure Rates ◽  
Nest Failure ◽  
Song Sparrows ◽  
Egg Removal

Abstract A removal experiment was conducted to measure how much and by what mechanisms brood parasitic Brown-headed Cowbirds (Molothrus ater) cause nest failures in a commonly used host, the Song Sparrow (Melospiza melodia). When numbers of female cowbirds were reduced experimentally, nest failures fell from 65.0% (n = 663 nests) to 49.9% (n = 331). Cowbird reduction reduced the frequency of nest failure to one-third of control levels in Song Sparrows during the last 80 days of the sparrow's breeding season, the period when most parasitic laying took place. Cowbird reduction decreased nest failures strongly at the egg stage, and weakly at the nestling stage. Daily nest-failure rates were independent of whether or not a nest was parasitized by cowbirds. Two hypotheses were tested to explain how cowbirds cause host nests to fail: first, egg removal by female cowbirds lowers clutch size below a threshold where the host deserts; second, cowbirds cause host nests to fail by destroying entire clutches or broods. In support of the first hypothesis, desertion following parasitism and egg removal was less frequent when cowbird numbers were reduced (8.9% of n = 158 nests) than for unmanipulated controls (16.5% of n = 424 nests). In support of the second hypothesis, there were fewer cases where young were killed in the nest, or found dead near it, after cowbird numbers were reduced (2.5% of 158 nests) than in controls (4.7% of 424 control nests). In contrast, proportions of nests that failed after the disappearance of all eggs, young, or both, and after unparasitized clutches were deserted, increased when cowbird numbers were reduced. Although our study supports both hypotheses, cowbird-induced desertion had a greater effect on nest failure rates than did cowbird predation. Our study suggests that cowbird removal programs are likely to benefit commonly used and endangered hosts by reducing rates of nest failure.

scholarly journals The effects of habituation on boldness of urban and rural song sparrows (Melospiza melodia)

Behaviour ◽  
2021 ◽  
pp. 1-15
Author(s):  
Taylor Elaine Fossett ◽  
Jeremy Hyman
Keyword(s):  
Repeated Exposure ◽  
Melospiza Melodia ◽  
Song Sparrow ◽  
Rural Populations ◽  
Flight Initiation Distance ◽  
Urban Birds ◽  
Wildlife Species ◽  
Song Sparrows ◽  
Rural And Urban ◽  
Flight Initiation

Abstract As urbanization increases globally, wildlife species are changing their behaviour in many ways. Urban animals are often bolder, or less fearful of new stimuli, than rural animals. While adaptation can drive behavioural changes in urban animals, other factors, such as learning or habituation, can also lead to behavioural modifications. To determine how repeated exposure to a non-threatening human affects song sparrow (Melospiza melodia) behaviour in urban and rural habitat, we measured boldness as flight initiation distance (FID), for 5 consecutive days. We found that urban birds had consistently lower FID’s than their rural counterparts from days 1–4, yet there was no difference in rural and urban FID by trial 5. FID decreased over 5 days of repeated trials in the rural populations, but not the urban. These results suggest that habituation can occur quickly in rural birds and may account for the greater boldness we typically see in urban populations.

scholarly journals High Level of Song Sharing in an Eastern Population of Song Sparrow (Melospiza Melodia)

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Jennifer R. Foote ◽  
Colleen A. Barber
Keyword(s):  
Song Learning ◽  
Melospiza Melodia ◽  
Song Sparrow ◽  
First Year ◽  
Eastern Population ◽  
Song Sharing ◽  
Song Sparrows ◽  
The Mean ◽  
High Level ◽  
Song Types

Abstract Using shared songs is believed to be an integral part of neighbor communication and territory establishment strategies among many avian species with repertoires. Previous studies of two western subspecies of Song Sparrows (Melospiza melodia) reported a high level of song sharing among neighboring males, whereas studies of an eastern subspecies have reported a very low level. The purpose of our study was to investigate another population of the eastern subspecies to determine whether higher song-sharing levels existed within its range. Every song in the repertoire of 29 males was compared with the songs of all other males to assess the number of shared songs. For each male, we calculated the mean song-sharing level with neighbors and non-neighbors. Males shared, on average, 33% of their repertoire with neighbors, significantly more than they shared with non-neighbors (27% of their repertoire). Two first-year males learned whole song types from several individuals and preferentially learned the song types shared among those individuals. Our results suggest that the eastern and western subspecies may not differ genetically in the way they learn songs, because song-sharing levels and song learning in our population were more similar to those of the western subspecies than to those of other populations within its own subspecies. Song-sharing differences among eastern populations may be explained instead by factors acting at the level of individual populations. Niveau Élevé de Chants Partagés chez une Population de l'Est de Melospiza melodia

Testing the function of song-matching in birds: responses of eastern male song sparrows Melospiza melodia to partial song-matching

Behaviour ◽  
2008 ◽  
Vol 145 (3) ◽  
pp. 347-363 ◽  
Author(s):  
William Searcy ◽  
Rindy Anderson ◽  
Stephen Nowicki
Keyword(s):  
Average Distance ◽  
Aggressive Response ◽  
Melospiza Melodia ◽  
Song Sparrow ◽  
Song Type ◽  
Eastern Population ◽  
Partial Matching ◽  
Male Song ◽  
Song Sparrows ◽  
Song Types

AbstractSong-matching has been hypothesized to be a signal of aggressive intentions whereby matching an opponent signals that the singer is likely to attack. Theory predicts that an aggressive signal should impose a cost that enforces the signal's reliability. A receiver-dependent cost imposed by the matched bird's aggressive retaliation has been proposed for song-matching. We tested for such a cost for partial song-matching in an eastern population of song sparrows where males lack the shared song types necessary for song type matching, but can perform partial song-matching using shared song segments. We tested aggressive response, as measured by average distance to a playback speaker, to partial-matching songs and non-matching songs. We predicted a stronger aggressive response to partial-matching songs, as has been shown for whole song-matching in western song sparrow populations. The birds in our study responded no differently to partial-matching and non-matching songs. Neither the distance to the playback speaker nor singing responses differed between playback treatments. Our results do not support a receiver-dependent cost to partial song-matching, as would be expected if partial-matching is a direct threat. Instead, we suggest that partial song-matching functions as a signal of attention.

HOW DO BROWN-HEADED COWBIRDS (MOLOTHRUS ATER) CAUSE NEST FAILURES IN SONG SPARROWS (MELOSPIZA MELODIA)? A REMOVAL EXPERIMENT

The Auk ◽  
2003 ◽  
Vol 120 (3) ◽  
pp. 772 ◽  
Author(s):  
James N.M. Smith ◽  
Mary J. Taitt ◽  
Liana Zanette ◽  
Isla H. Myers-Smith
Keyword(s):  
Molothrus Ater ◽  
Melospiza Melodia ◽  
Removal Experiment ◽  
Song Sparrows

Costs of multiple parasitism for an avian brood parasite, the Brown-headed Cowbird (Molothrus ater)

2011 ◽  
Vol 89 (12) ◽  
pp. 1237-1248 ◽  
Author(s):  
C.B. Goguen ◽  
D.R. Curson ◽  
N.E. Mathews
Keyword(s):  
New Mexico ◽  
Intraspecific Competition ◽  
Molothrus Ater ◽  
Brood Parasite ◽  
Egg Survival ◽  
Host Nest ◽  
Egg Mortality ◽  
Nest Desertion ◽  
Nestling Period ◽  
Polioptila Caerulea

The Brown-headed Cowbird ( Molothrus ater (Boddaert, 1783)) is a generalist brood parasite that often lays into nests that contain conspecific eggs. Although it has often been assumed that this multiple parasitism reduces Cowbird survival, this has rarely been evaluated. We measured Cowbird survival in nests of the Blue-gray Gnatcatcher ( Polioptila caerulea (L., 1766)), Plumbeous Vireo ( Vireo plumbeus Coues, 1866), and Western Tanager ( Piranga ludoviciana (A. Wilson, 1811)) in New Mexico, USA. Our objectives were to measure the costs of intraspecific competition on Cowbird survival in multiply-parasitized nests, evaluate if these costs were related to host size, and to compare the costs of multiple parasitism relative to other mortality sources that occur over the entire nesting cycle. Intraspecific competition reduced Cowbird survival during the nestling period in nests of all three hosts, and was of particular importance in nests of the two smaller hosts. When all sources of egg mortality were considered, however, the costs of multiple parasitism were small compared with the large effects of predation and nest desertion. Given that multiple parasitism reduces Cowbird egg survival, it is unclear why Cowbirds multiply-parasitize. Possible explanations depend on an improved understanding of fecundity and level of host nest selectivity by female Cowbirds.

Foraging habitat and diet of Song Sparrows (Melospiza melodia) nesting in farmland: a stable isotope approach

2012 ◽  
Vol 90 (11) ◽  
pp. 1339-1350 ◽  
Author(s):  
J. Girard ◽  
A. Baril ◽  
P. Mineau ◽  
L. Fahrig
Keyword(s):  
North America ◽  
Melospiza Melodia ◽  
Food Sources ◽  
Song Sparrow ◽  
Foraging Habitat ◽  
Farmland Birds ◽  
Mean Values ◽  
Minimal Impact ◽  
Management Actions ◽  
Song Sparrows

Agricultural intensification has been linked to declines in farmland and grassland bird populations in Europe and in North America. One factor thought to be behind these declines is reduced invertebrate food abundance in the breeding season, leading to reduced reproductive success. However, little is known about foraging habitat or diet of farmland birds in North America. We used stable isotopes to study foraging habitat and diet of Song Sparrows ( Melospiza melodia (A. Wilson, 1810)), a common hedgerow-breeding bird, by collecting claw clippings of Song Sparrow nestlings from farms in eastern Ontario, Canada. Mean values of δ13C and δ15N were compared between claws and invertebrate food sources from adjacent land-cover types, using a Bayesian mixing model. The portion of nestling diet that came from seminatural and forage habitats was higher than expected, based on the proportion of seminatural and forage cover at the nest. This was particularly evident at nests with low seminatural cover, where hedgerows were the only noncrop habitat. The most important food sources for Song Sparrow nestlings were hoppers (Auchenorrhyncha) and caterpillars (Lepidoptera). Management actions to increase invertebrate abundance in hedgerows may benefit Song Sparrows and other farmland birds with minimal impact on crop yield.

scholarly journals Sheep in wolf's clothing: host nestling vocalizations resemble their cowbird competitor's

2008 ◽  
Vol 275 (1638) ◽  
pp. 1061-1065 ◽  
Author(s):  
Katie Pagnucco ◽  
Liana Zanette ◽  
Michael Clinchy ◽  
Marty L Leonard
Keyword(s):  
Parental Care ◽  
Molothrus Ater ◽  
Dynamic Interaction ◽  
Melospiza Melodia ◽  
Song Sparrow ◽  
Brood Parasites ◽  
Parental Provisioning ◽  
Egg Mimicry

Nestlings of many avian brood parasites are virtuosos at mimicking host nestling vocalizations, which, like egg mimicry, presumably ensures acceptance by host parents. Having been accepted, parasitic nestlings then often exaggerate the aspects of the host's display to increase parental care. Host nestlings may, in turn, exaggerate their vocalizations to keep up with the parasite, though this possibility has not been evaluated. We experimentally parasitized song sparrow ( Melospiza melodia ) nests with a brown-headed cowbird ( Molothrus ater ) chick to evaluate how host nestlings respond. Vocalizations emitted from experimentally parasitized nests were higher in frequency, and louder, than those from unparasitized nests, consistent with the cowbird exaggerating its signalling. In response, host nestlings exaggerated the frequency and amplitude of their vocalizations, such that they resembled the cowbird's while they ‘scaled back’ on calls per parental provisioning bout. Sparrows in parasitized nests were fed equally often as sparrows in unparasitized nests, suggesting that exaggerating some aspects of vocalization while scaling back on others can help host nestlings confronted with a cowbird. Our results support the recently proposed hypothesis that signalling in parasitized nests involves a dynamic interaction between parasitic and host nestlings, rather than a one-way process of mimicry by the parasite.

scholarly journals Risk allocation: acute and chronic predator exposure have contrasting effects on Song Sparrow (Melospiza melodia) singing behaviour

2019 ◽  
Vol 97 (3) ◽  
pp. 258-266
Author(s):  
Anne Margaret Ellison ◽  
Ron Ydenberg
Keyword(s):  
Risk Taking ◽  
Melospiza Melodia ◽  
Acute Exposure ◽  
Song Sparrow ◽  
Risk Allocation ◽  
Territorial Defense ◽  
Accipiter Cooperii ◽  
The Past ◽  
Song Sparrows ◽  
Predation Danger

Increasing the danger posed by predators may cause prey animals to alter their behaviour. For example, they may be more vigilant and so feed more slowly. Breeding male Song Sparrows (Melospiza melodia (A. Wilson, 1810)) spend much time in conspicuous, loud song, which is an important behaviour for territorial defense and for mate attraction. We measured their singing behaviour in relation to both chronic (active Cooper’s Hawk (Accipiter cooperii (Bonaparte, 1828)) nest nearby) and acute (playback of hawk calls) predator exposure. We found that proximity to a Cooper’s Hawk nest had little or no influence. In contrast, the response to acute exposure was strong and immediate: Song Sparrows reduced the song rate and the proportion of time spent singing, lowered perch height, and increased concealment. The decline in the amount of song during the few minutes following playback attributable to the acute exposure was 34.6%. We analyze these results in light of theories about how animals adjust risk taking in response to predation danger. Given that the numbers of their predators have risen steadily for the past few decades and affect the level of singing, we consider the implications for trend estimates of songbird populations based on surveys using auditory methods.

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