scholarly journals Agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period

2016 ◽  
Vol 12 (6) ◽  
pp. 20160315 ◽  
Author(s):  
Scott Davies ◽  
Kendra B. Sewall
Keyword(s):  
Rural Areas ◽  
Ecological Factors ◽  
Plasma Testosterone ◽  
Breeding Period ◽  
Urban Birds ◽  
Breeding Sites ◽  
Territorial Aggression ◽  
Conspecific Density ◽  
Song Sparrows ◽  
Behavioural Difference

Urban birds often more vigorously defend their territories during simulated intrusions than do their rural counterparts, but the factors responsible remain unclear. To address this issue, we investigated whether the disparity in territorial aggression of urban and rural male song sparrows, Melospiza melodia , is individually consistent within a breeding period. Additionally, to better understand the physiological and ecological factors underlying this behavioural difference, we examined whether territoriality was associated with plasma testosterone, a hormone that contributes to elevated aggression in vertebrates, and/or conspecific density, a factor often positively related to aggression. The urbanization-related difference in territoriality was individually consistent within a breeding period. However, the elevated territorial aggression of urban birds was not associated with plasma testosterone and, counter to our predictions, conspecific density was lower in urban compared with rural areas. We suggest that other aspects of testosterone signalling and features of the socio-ecological environment, such as the availability of breeding sites, may underlie increased territorial aggression in urban birds.

Individual Variation in the Strength of Territory Defense in Male Song Sparrows: Correlates of Age, Territory Tenure, and Neighbor Aggressiveness

Behaviour ◽  
2004 ◽  
Vol 141 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Jeremy Hyman ◽  
Melissa Hughes ◽  
Stephen Nowicki ◽  
William Searcy
Keyword(s):  
Individual Differences ◽  
Reproductive Success ◽  
Extrinsic Factors ◽  
Territory Defense ◽  
Intrinsic Factors ◽  
Territorial Aggression ◽  
Male Song ◽  
Song Sparrows ◽  
Territory Owner ◽  
Older Males

AbstractIn many species, the ability to defend a territory is essential for a male to obtain any reproductive success at all, and even among territorial individuals, variation in the strength of territory defense could have a significant impact on how much reproductive success is obtained. Previous studies have documented consistent individual differences in the vigor with which male song sparrows (Melospiza melodia) defend their territories, as measured by the strength of their reactions to territorial intrusions simulated through song playback. Variation in the strength of defense could reflect intrinsic differences among individuals in their resource holding potential (RHP), or variation in extrinsic factors. In this study, we examined whether variation in the strength of territory defense corresponds to differences in intrinsic factors such as the age or experience of the territory owner, the extrinsic factor of the level of aggression shown by neighbours, or both. Results indicate that males that previously held territories on the study site, regardless of whether they were holding the same territory as the previous year, show higher levels of territory defense than males that are new to the study site, and, assuming that returning males are older males, suggest that age is more important than experience on a specific territory in determining strength of territory defense. In addition, we found evidence that males with high levels of territorial aggression tend to be spatially clustered. The pattern observed suggests that a combination of intrinsic and extrinsic factors contribute to the expression of individual differences in territorial aggression.

scholarly journals Rise-Up mist-netting (RUM): a mobile protocol for trapping wary territorial birds

2021 ◽  
Vol 61 ◽  
pp. e20216110
Author(s):  
Paulo Sérgio Amorim ◽  
Mariana Fonseca Rossi ◽  
André de Camargo Guaraldo
Keyword(s):  
Urban Area ◽  
Rural Areas ◽  
Urban Areas ◽  
General Public ◽  
Bird Species ◽  
Breeding Period ◽  
The Novel ◽  
Limited Space ◽  
Trapping Methods ◽  
Visual Impacts

Many bird species avoid traditional traps such as mist nets, thus alternative trapping methods are often needed. The Rufous Hornero (Furnariidae: Furnarius rufus) is one such species that was captured so far using conventional mist netting in rural areas or using nest-targeted traps, which risk nest damage and abandonment. Here we describe the novel rise-up mist-netting (RUM) protocol and its catchability for the wary and territorial Rufous Hornero in an urban area. The RUM trap allowed us quickly capturing 40 Rufous Hornero individuals even in paved parking lots and streets during the bird’s breeding period. The RUM is an active and targeted protocol that demands a single and quickly trainable field assistant. Therefore, it should also enable the capture of many understudied territorial but wary species. Moreover, it has enough mobility to fit studies in urban areas, and whenever researchers may deal with limited space and, at the same time, should reduce negative visual impacts to the general public of birds’ capturing and banding procedures.

scholarly journals Tolerance to Human Presence, a Comparison between Rural and Urban Birds in Southeastern Brazil

2021 ◽  
Vol 2 (3) ◽  
pp. 1-4
Author(s):  
Maria Cecília Barbosa de Toledo
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Bird Species ◽  
Urban Environments ◽  
Southeastern Brazil ◽  
Special Focus ◽  
Forest Fragments ◽  
Urban Birds ◽  
Human Presence ◽  
Individual Bird

Green urban areas such as parks, squares, gardens, and forest fragments present a large diversity of uses and conservation objectives. These spaces provide resources for many species of birds that are confronted with the necessity of living in proximity to humans. It is assumed that bird species that acquire resources in urban environments live in a constant state of fear to guarantee survival and reproduction. In this context, the objective of this study was to evaluate the tolerance of birds with respect to human presence in two distinct conditions, rural areas (low level of human presence) and urban areas (high level of human presence). The fieldwork was conducted in a city in the Southeast region of Brazil, and the methodology used the alert distance and flight initiation measurements based on the approach of an observer to the individual bird being focused. Our results suggest that individuals observed in urban areas rely on shorter alert and escape distances, especially males, adults, and birds that forage in interspecific flocks. We discuss the challenges and strategies with respect to escape characteristics of urban birds, with special focus on the economic escape theory. In general, our results support those from studies conducted in other urban areas in different biogeographic regions, and they will aid in comprehending the impacts caused by the increase in urban areas around the world.

Seasonal reproduction in the highveld mole-rat, Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

2002 ◽  
Vol 80 (5) ◽  
pp. 810-820 ◽  
Author(s):  
L Janse van Rensburg ◽  
N C Bennett ◽  
M van der Merwe ◽  
A S Schoeman
Keyword(s):  
Body Mass ◽  
Reproductive Tract ◽  
Plasma Testosterone ◽  
Breeding Period ◽  
Corpora Lutea ◽  
Seasonal Breeding ◽  
Nonbreeding Season ◽  
Ovarian Histology ◽  
Mole Rat ◽  
Reproductive Females

The highveld mole-rat, Cryptomys hottentotus pretoriae, is a cooperatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive-tract morphometrics, ovarian histology, and plasma oestrogen and progesterone concentrations were studied for both reproductive and non-reproductive females from 55 colonies, the main objective being to determine the inclination of this species towards seasonal breeding. Offspring are born from July through to November. However, qualitative analysis of ovarian histology revealed that reproductive females retain the potential for ovulation and subsequent production of corpora lutea during the late-summer nonbreeding period (December–March). Seasonal differences were found in ovarian morphometrics and hormone concentrations that are associated with enhanced follicular activation in April and May and subsequent conceptions from July through to November during the breeding period. The nonbreeding period coincides with maximal dispersal opportunities in the summer-rainfall areas inhabited by the highveld mole-rat. Body mass, reproductive-tract morphometrics, testicular histology, and plasma testosterone concentrations were determined for reproductive and non-reproductive males from 37 colonies. Available evidence suggests that there is a gradual increase in testicular mass for reproductive males as the breeding season approaches, but after September the testicular parameters fall. Seminiferous-tubule diameter was significantly greater in reproductive males but exhibited no seasonal variation. Testosterone concentrations were higher in reproductive males. Current data support a lack of gonadal regression in males during the nonbreeding season.

scholarly journals Are signals of aggressive intent less honest in urban habitats?

2019 ◽  
Author(s):  
Çağlar Akçay ◽  
Michelle L Beck ◽  
Kendra B Sewall
Keyword(s):  
Acoustic Noise ◽  
Visual Signals ◽  
Acoustic Properties ◽  
Urban Habitats ◽  
Urban Birds ◽  
Urban Noise ◽  
Song Sparrows ◽  
Soft Song ◽  
Close Range ◽  
Low Amplitude

Abstract How anthropogenic change affects animal social behavior, including communication is an important question. Urban noise often drives shifts in acoustic properties of signals but the consequences of noise for the honesty of signals—that is, how well they predict signaler behavior—is unclear. Here we examine whether honesty of aggressive signaling is compromised in male urban song sparrows (Melospiza melodia). Song sparrows have two honest close-range signals: the low amplitude soft songs (an acoustic signal) and wing waves (a visual signal), but whether the honesty of these signals is affected by urbanization has not been examined. If soft songs are less effective in urban noise, we predict that they should predict attacks less reliably in urban habitats compared to rural habitats. We confirmed earlier findings that urban birds were more aggressive than rural birds and found that acoustic noise was higher in urban habitats. Urban birds still sang more soft songs than rural birds. High rates of soft songs and low rates of loud songs predicted attacks in both habitats. Thus, while urbanization has a significant effect on aggressive behaviors, it might have a limited effect on the overall honesty of aggressive signals in song sparrows. We also found evidence for a multimodal shift: urban birds tended to give proportionally more wing waves than soft songs than rural birds, although whether that shift is due to noise-dependent plasticity is unclear. These findings encourage further experimental study of the specific variables that are responsible for behavioral change due to urbanization. Soft song, the low amplitude songs given in close range interactions, is an honest threat signal in urban song sparrows. Given its low amplitude, soft songs may be a less effective signal in noisy urban habitats. However, we found that soft song remained an honest signal predicting attack in urban habitats. We also found that birds may use more visual signals (rapid fluttering of wings) in urban habitats to avoid masking from acoustic noise.

scholarly journals Multiscale determinants of Pacific chorus frog occurrence in a developed landscape

2020 ◽  
Author(s):  
Jemma Green ◽  
Purnima Govindarajulu ◽  
Eric Higgs
Keyword(s):  
Rural Areas ◽  
Negative Impact ◽  
Spatial Scales ◽  
Rural Landscape ◽  
Landscape Conservation ◽  
Terrestrial Habitat ◽  
Breeding Sites ◽  
Impervious Cover ◽  
Primary Driver ◽  
Chorus Frog

Abstract Pacific chorus frog (Pseudacris regilla) populations have persisted despite urban and rural development throughout the species’ range; yet it is possible that P. regilla, like other anurans with which it historically co-occurred, will become extirpated from cities and suburbs if urbanization intensifies as predicted. An improved understanding of the conditions that enable this species to persist in developed landscapes is needed to identify and conserve suitable habitats. We investigated species-habitat relationships for P. regilla in a mixed urban-rural landscape in southwestern British Columbia, Canada, to identify potential criteria for habitat suitability. We conducted repeat auditory surveys of chorusing males at 52 potential breeding wetlands and modeled occupancy at 26 of these sites using local and landscape variables representing competing hypotheses and spatial scales of influence. The models that best explained P. regilla occupancy included a combination of terrestrial habitat and connectivity factors and the presence of non-native predators. We found that the proportion of impervious cover within 250 m of a wetland had the strongest negative impact on occupancy. Our findings suggest that availability of terrestrial habitat adjacent to breeding sites is the primary driver of species presence in the developed landscape. Conservation efforts should seek to limit impervious cover to less than 20% within a 250-m buffer around breeding wetlands. Further, restored and created wetlands in urban and rural areas may be more likely to support P. regilla if they are designed with a seasonal hydroperiod that excludes non-native aquatic predators and are placed in an area of high pond density.

scholarly journals Song sparrows Melospiza melodia have a home-field advantage in defending against sympatric malarial parasites

2016 ◽  
Vol 3 (8) ◽  
pp. 160216 ◽  
Author(s):  
Yanina Sarquis-Adamson ◽  
Elizabeth A. MacDougall-Shackleton
Keyword(s):  
Melospiza Melodia ◽  
The Other ◽  
Ecological Interactions ◽  
Breeding Sites ◽  
Song Sparrows ◽  
Capture Site ◽  
Fitness Consequences ◽  
Home Field Advantage ◽  
Fitness Consequence ◽  
Host Parasite

Hosts and parasites interact on both evolutionary and ecological timescales. The outcome of these interactions, specifically whether hosts are more resistant to their local parasites (sympatric) than to parasites from another location (allopatric), is likely to affect the spread of infectious disease and the fitness consequences of host dispersal. We conducted a cross-infection experiment to determine whether song sparrows ( Melospiza melodia ) have an advantage in dealing with sympatric parasites. We captured birds from two breeding sites 437 km apart, and inoculated them with avian malaria ( Plasmodium spp.) cultured either from their capture site or from the other site. Infection risk was lower for birds exposed to sympatric than to allopatric Plasmodium lineages, suggesting that song sparrows may have a home-field advantage in defending against local parasite strains. This pattern was more pronounced at one capture site than at the other, consistent with mosaic models of host–parasite interactions. Home-field advantage may arise from evolutionary processes, whereby host populations become adapted to their local parasites, and/or from ecological interactions, whereby host individuals develop resistance to the local parasites through previous immune exposure. Our findings suggest that greater susceptibility to novel parasites may represent a fitness consequence of natal dispersal.

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