Additive negative effects of Philornis nest parasitism on small and declining Neotropical bird populations

2018 ◽  
Vol 29 (03) ◽  
pp. 339-360 ◽  
Author(s):  
MARIANA BULGARELLA ◽  
MARTÍN A. QUIROGA ◽  
GEORGE E. HEIMPEL
Keyword(s):  
Bird Species ◽  
Field Studies ◽  
Habitat Destruction ◽  
Biological Information ◽  
Mortality Factor ◽  
Healthy Population ◽  
Small Populations ◽  
Negative Effects ◽  
Nest Parasitism ◽  
Bird Populations

SummaryThe declining-population paradigm holds that small populations are particularly vulnerable to anthropogenic influences such as habitat destruction, pollution and species introductions. While the effects of particular stressors, such as parasitism, may be unimportant in a large, healthy population, they can be serious and even devastating in situations characterised by a restricted geographic range, or by fragmented or reduced population sizes. We apply this idea to nest parasitism of threatened Neotropical bird species that exist in small populations, focusing on dipteran nest parasites in the genusPhilornis. We review the literature onPhilornisparasitism exerting negative pressure on bird populations that have become small and isolated due to human actions and present a new case ofPhilornisparasitism of a threatened hummingbird species. Our aim is to raise awareness about the exacerbating effect that nest parasites can have on small and declining bird populations; especially when biological information is scarce. The five reviewed cases involve two species of Darwin’s Finches in the Galápagos Islands attacked by the invasiveP. downsi, two species of hawks on islands in the Caribbean attacked by the nativeP. piciandP. obscura, and the Yellow CardinalGubernatrix cristatain southern South America attacked by an unknownPhilornisspecies. We also present new documentation of parasitism of a threatened hummingbird species in mainland Ecuador by an unidentifiedPhilornisspecies. We recommend more field studies to determine the presence of nest parasites in bird populations worldwide to improve understanding how nest parasites affect bird fitness and population viability and to allow time to act in advance if needed. Parasitism byPhilornismay represent a severe mortality factor in most already threatened bird species, putting them at greater risk of extinction. Therefore, parasitism management should be included in all threatened species recovery plans.

scholarly journals Macroecology of birds potentially susceptible to West Nile virus

2018 ◽  
Vol 285 (1893) ◽  
pp. 20182178 ◽  
Author(s):  
María J. Tolsá ◽  
Gabriel E. García-Peña ◽  
Oscar Rico-Chávez ◽  
Benjamin Roche ◽  
Gerardo Suzán
Keyword(s):  
West Nile Virus ◽  
Spatial Scales ◽  
Animal Health ◽  
Bird Species ◽  
Field Studies ◽  
Zoonotic Diseases ◽  
West Nile ◽  
Bird Populations ◽  
Time Space ◽  
Wildlife Pathogens

Zoonotic diseases transmitted by wildlife affect biological conservation, public and animal health, and the economy. Current research efforts are aimed at finding wildlife pathogens at a given location. However, a meta-analytical approach may reveal emerging macroecological patterns in the host–pathogen relationship at different temporal and spatial scales. West Nile virus (WNV) is a pathogen with worldwide detrimental impacts on bird populations. To understand macroecological patterns driving WNV infection, we aimed to recognize unknown competent reservoirs using three disease metrics—serological prevalence (SP), molecular prevalence (MP) and mortality (M)—and test if these metrics are correlated with the evolutionary history, geographical origin of bird species, viral strain, time–space and methodology. We performed a quantitative review of field studies on birds sampled for WNV. We obtained 4945 observations of 949 species from 39 countries. Our analysis supported the idea that MP and M are good predictors of reservoir competence, and allowed us to identify potential competent reservoirs. Furthermore, results indicated that the variability of these metrics was attributable to phylogeny, time–space and sample size. A macroecological approach is needed to recognize susceptible species and competent reservoirs, and to identify other factors driving zoonotic diseases originating from wildlife.

scholarly journals The Ghost of the Hawk: Top Predator Shaping Bird Communities in Space and Time

2021 ◽  
Vol 9 ◽  
Author(s):  
Daniel Burgas ◽  
Otso Ovaskainen ◽  
F. Guillaume Blanchet ◽  
Patrik Byholm
Keyword(s):  
Species Interactions ◽  
Species Distribution Model ◽  
Bird Species ◽  
Keystone Species ◽  
Distribution Model ◽  
Top Predator ◽  
Negative Effects ◽  
Bird Populations ◽  
Large Bird ◽  
Northern Goshawks

Despite the wide recognition that strongly interacting species can influence distributions of other species, species interactions are often disregarded when assessing or projecting biodiversity distributions. In particular, it remains largely uncharted the extent to which the disappearance of a keystone species cast repercussions in the species composition of future communities. We tested whether an avian top predator can exert both positive and negative effects on spatial distribution of other species, and if these effects persist even after the predator disappeared. We acquired bird count data at different distances from occupied and non-occupied nests of Northern goshawks Accipiter gentilis. Using a Bayesian joint species distribution model, we found that large bird species (preferred prey) are less abundant in the proximity of nests occupied by goshawks, whereas smaller species –expected to get protection from subordinate predators displaced by goshawks– more often showed an opposite association. These spatial differences level off gradually, but still persist for years after the goshawks have disappeared. This indicates that the composition of local bird populations and communities might be conditional on past species interactions. Therefore, endeavors centered around species distributions could largely benefit from acknowledging the local extinction of keystone species.

scholarly journals Weak Effects of Owned Outdoor Cat Density on Urban Bird Richness and Abundance

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 507
Author(s):  
Genevieve C. Perkins ◽  
Amanda E. Martin ◽  
Adam C. Smith ◽  
Lenore Fahrig
Keyword(s):  
Urban Areas ◽  
Bird Species ◽  
Lethal Effect ◽  
Bird Communities ◽  
Domestic Cats ◽  
Urban Birds ◽  
Negative Effects ◽  
Bird Populations ◽  
Bird Richness ◽  
Urban Bird

Domestic cats (Felis catus) are ubiquitous predators of birds in urban areas. In addition to the lethal effect of predation, there can also be sublethal, negative effects of domestic cats on individual birds. These effects have led to the inference that reducing outdoor cat densities would benefit urban bird communities. Here we estimate the likely result of policies/programs designed to reduce densities of owned outdoor cats in urban areas, estimating relationships between bird richness/abundance and cat densities across 58 landscapes in Ottawa, Ontario, Canada. We estimate that we would most likely observe one additional bird species, and 0.003 additional individuals per species, if policies/programs reduced owned outdoor cat densities to zero in an average landscape in Ottawa (with 130.2 cats/km2). However, these effects of cat density on birds were uncertain, with 95% confidence intervals crossing zero. Our findings—in combination with those of previous studies—suggest a need for research to resolve the apparent disconnect between the strong, negative effects of cats on individual urban birds and the weak, uncertain effects of cats on bird populations. Although measures that reduce owned outdoor cat densities are justified based on the precautionary principle, evidence to date does not support prioritizing these measures over those addressing threats that have consistently strong effects on bird populations.

scholarly journals An Assessment on Bird’s Diversity in Bagmati River Corridor

1970 ◽  
Vol 2 (1) ◽  
pp. 34-40
Author(s):  
Saroj Thapa ◽  
Shambhu Paudel ◽  
Dipak BK
Keyword(s):  
Public Perception ◽  
Habitat Degradation ◽  
Bird Species ◽  
Habitat Destruction ◽  
Conservation Area ◽  
Point Count ◽  
The Public ◽  
One Year ◽  
Bagmati River ◽  
River Corridor

Bagmati River is considered as a potential conservation area in terms of the bio-diversity conservation due to its unique and diversified habitat distribution. Due to various causes, the river is being polluted and hence habitat degradation rate is increasing. As a consequence, the direct effect is seen on birds inhabiting there. Aiming the assessment of bird's diversity, one year survey was conducted in Bagmati River from Tilganga Bridge to chobhar Gorge Bridge (here after termed as Bagmati river corridor) by applying the point count method .In the total enumeration, 100 of birds species were recorded among which 7 are listed in CITES appendix. The bird species that are regarded as globally threatened are not recorded in the study area. In this report, some potential patches in the study area, are described as hot spots, considering the higher probability of recording maximum number of birds species. The public voice is also collected to find out the public perception on the present status of birds of Bagmati river corridor using the questionaire method. Some causes of habitat destruction and some potential conservation measures are also mentioned. Key Words: Bagmati river corridor, Birds, Conservation, Hotspots, Diversity, Habitat   DOI: 10.3126/init.v2i1.2520 The Initiation Vol.2(1) 2008 pp34-40

scholarly journals The Occurence of Ecological Traps in Bird Populations: Is our Knowledge Sufficient? A Review

2012 ◽  
Vol 5 (3) ◽  
pp. 36-56 ◽  
Author(s):  
Petr Suvorov ◽  
Jana Svobodová
Keyword(s):  
Exotic Species ◽  
Species Conservation ◽  
Habitat Type ◽  
Bird Species ◽  
Ecological Trap ◽  
Native Communities ◽  
Bird Populations ◽  
Suburban Areas ◽  
Arable Fields ◽  
Insufficient Time

ABSTRACT Anthropogenic changes in a landscape create new cues for birds, which must permanently adapt to these. If landscape changes occur too quickly, individuals have insufficient time to develop adequate reactions. They may, therefore, preferentially nest in low-quality habitats, which can lead to diminished nesting success and to reduction of their population size. This is usually termed the ecological trap hypothesis. We reviewed 38 studies investigating this phenomenon and analysed whether relationships exist between ecological trap occurrence and geographical region, habitat type, and/or life strategies of bird species. Ecological traps were most often associated with the presence of exotic species. Exotic species can modify environmental conditions in ways to which native communities are not adapted. They have been mainly detected in open habitats. Such open habitats as arable fields and meadows are under greater human pressure, and rapid changes probably occur there more frequently. Although more studies from North America were investigated, the hypothesis was supported more frequently in European studies. This is possibly due to higher human population density and, hence, more frequent habitat changes. Our results show that an ecological trap is not likely associated with migration. Ground nests suffered fewer consequences of such traps than did other nest types. Although the implications of the ecological trap hypothesis in species conservation are undisputable, a more detailed approach is still needed. For instance, some habitat types, such as suburban areas, have been neglected in the context of ecological traps, as has been the phenomenon’s appearance in pristine habitats.

scholarly journals Low effect on open-farmland birds of young afforestations in heterogeneous Mediterranean croplands

2014 ◽  
Author(s):  
Juan S. Sánchez-Oliver ◽  
José M. Rey Benayas ◽  
Luis M. L.M. Carrascal
Keyword(s):  
Species Richness ◽  
Bird Species ◽  
Agricultural Landscapes ◽  
Tree Plantations ◽  
Conservation Value ◽  
Farmland Birds ◽  
Negative Effects ◽  
Bird Species Richness ◽  
Positive Effects ◽  
The One

Afforestation programs such as the one promoted by the EU Common Agricultural Policy have spread tree plantations on former cropland. These afforestations attract generalist forest and ubiquitous species but may cause severe damage to open habitat species, especially birds of high conservation value. We investigated the effects of young (< 20 yr) tree plantations dominated by pine P. halepensis on bird communities inhabiting the adjacent open farmland habitat in central Spain. We hypothesize that pine plantations with larger surface, and areas at shorter distances from plantations, would result in lower bird species richness and conservation value of open farmland birds. Regression models controlling for the influence of land use types around plantations revealed significant positive effects of distance to pine plantation edge on community species richness in winter, and negative effects on an index of conservation concern (SPEC) during the breeding season. However, plantation area did not have any effect on species richness or community conservation value. Our results indicate that pine afforestation of Mediterranean cropland in heterogeneous agricultural landscapes has an overall low detrimental effect on bird species that are characteristic of open farmland habitat.

Uncovering the Mitigating Psychological Response to Monitoring Technologies: Police Body Cameras Not Only Constrain but Also Depolarize

2021 ◽  
Author(s):  
Shefali V. Patil ◽  
Ethan S. Bernstein
Keyword(s):  
Law Enforcement ◽  
Strong Support ◽  
Field Studies ◽  
Negative Effects ◽  
Technological Advances ◽  
Ideological Divergence ◽  
Monitoring Technologies ◽  
Ideological Tensions ◽  
Shed Light ◽  
Psychological Benefit

Despite organizational psychologists’ long-standing caution against monitoring (citing its reduction in employee autonomy and thus effectiveness), many organizations continue to use it, often with no detriment to performance and with strong support, not protest, from employees. We argue that a critical step to resolving this anomaly is revisiting researchers’ fundamental assumptions about access to gathered data. Whereas previous research assumes that access resides nearly exclusively with supervisors and other evaluators, technological advances have enabled employee access. We hypothesize that with employee access, the psychological effects of monitoring may be far more complex than previously acknowledged. Whereas multiparty access may still decrease employee autonomy, it may also trigger an important psychological benefit: alleviating employees’ perceptions of polarization—the increasing social and ideological divergence between themselves and their evaluators. Access gives employees unprecedented opportunities to use the “objective” footage to show others their perspective, address evaluators’ erroneous assumptions and stereotypes, and otherwise defuse ideological tensions. Lower perceived polarization, in turn, attenuates the negative effects that low autonomy would otherwise have on employee effectiveness. We find support for these hypotheses across three field studies conducted in the law enforcement context, which has been a trailblazer in using technological advances to grant broad access to multiple parties, including employees. Overall, our studies shed light on the conflicting (and ultimately more innocuous) impact of monitoring and encourage scholars to break from prior approaches to account for its increasing egalitarianism.

scholarly journals Nine Years After the Exxon Valdez Oil Spill: Effects on Marine Bird Populations in Prince William Sound, Alaska

The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 723-737 ◽  
Author(s):  
David B. Irons ◽  
Steven J. Kendall ◽  
Wallace P. Erickson ◽  
Lyman L. McDonald ◽  
Brian K. Lance
Keyword(s):  
Oil Spill ◽  
Bird Species ◽  
Population Level ◽  
Prince William Sound ◽  
Negative Effects ◽  
Exxon Valdez ◽  
Marine Bird ◽  
Marine Birds ◽  
Exxon Valdez Oil Spill ◽  
Positive Effects

Abstract We compared post Exxon Valdez oil-spill densities of marine birds in Prince William Sound from 1989–1991, 1993, 1996, and 1998 to pre-spill densities from 1984–1985. Post-spill densities of several species of marine birds were lower than expected in the oiled area of Prince William Sound when compared to densities in the unoiled area. These negative effects continued through 1998 for five taxa: cormorants, goldeneyes, mergansers, Pigeon Guillemot (Cepphus columba), and murres. Black Oystercatchers (Haematopus bachmani) and Harlequin Ducks (Histrionicus histrionicus) exhibited negative effects in 1990 and 1991. Loons showed a weak negative effect in 1993. Black-legged Kittiwakes (Rissa tridactyla) showed relative decreases in 1989, 1996, and 1998 which may have been caused by shifts in foraging distribution rather than declines in populations. Glaucous-winged Gulls (Larus glaucescens) showed positive effects in most post-spill years. Murrelets and terns showed relative increases in 1993, 1996, and 1998. Generally, taxa that dive for their food were negatively affected, whereas taxa that feed at the surface were not. Effects for some taxa were dependent upon the spatial scale at which they were analyzed. Movements of birds and the mosaic pattern of oiling reduced our ability to detect oil-spill effects, therefore our results may be conservative. Several marine bird species were negatively affected at the population level and have not recovered to pre-spill levels nine years after the oil spill. The reason for lack of recovery may be related to persistent oil remaining in the environment and reduced forage fish abundance.

scholarly journals Diversity, Uses, and Threats in the Ghodaghodi Lake Complex, a Ramsar Site in Western Lowland Nepal

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Pramod Lamsal ◽  
Krishna Prasad Pant ◽  
Lalit Kumar ◽  
Kishor Atreya
Keyword(s):  
Aquatic Macrophytes ◽  
Irrigation System ◽  
Local Level ◽  
Bird Species ◽  
Habitat Destruction ◽  
Population Pressure ◽  
Conservation Strategies ◽  
Seepage Water ◽  
Ramsar Site ◽  
Anthropogenic Threats

This study documents aquatic and terrestrial/riparian biodiversity in an anthropogenically disturbed Ramsar site, the Ghodaghodi Lake complex, in the Western Nepal surveyed during the summer season (March-April) of 2007. The study site comprises three major interconnected lakes: Ghodaghodi (138 ha), Nakharodi (70 ha), and Bainshwa (10 ha). Five transect lines for aquatic macrophytes and three transect lines and 37 sampling plots were laid to sample terrestrial/riparian plants, birds, and animals. Five sample plots were established for fish and aquatic bird. A total of 45 species of aquatic macrophytes, 54 species of terrestrial/riparian vegetation, 19 fish species, 41 bird species, 17 mammals (endangered and vulnerable), and 5 reptiles (critically endangered, vulnerable, and near threatened) were recorded at the lake complex. Local people have used most of the aquatic and terrestrial plants for different purposes while many of the potential medicinal plant species were still untapped. Persistent anthropogenic threats, like excessive harvesting and poaching, habitat destruction—population pressure, forest fragmentation, siltation, fertilizer and pesticide seepage, water pollution, overgrazing, and unmanaged irrigation system found over the lake complex, endangered the existing biodiversity. The suggested remedial measures are further exploration of medicinal potential, prioritization of in situ biodiversity conservation strategies, and implementation of awareness program at local level against anthropogenic threats.

scholarly journals Unhatched eggs represent the invisible fraction in two wild bird populations

2020 ◽  
Vol 16 (1) ◽  
pp. 20190763 ◽  
Author(s):  
Nicola Hemmings ◽  
Simon Evans
Keyword(s):  
Life History ◽  
Wild Bird ◽  
Evolutionary Dynamics ◽  
Population Studies ◽  
Bird Species ◽  
Fertilization Failure ◽  
Bird Populations ◽  
Life History Data ◽  
Evolutionary Inference ◽  
The Invisible

Prenatal mortality is typically overlooked in population studies, which biases evolutionary inference by confounding selection and inheritance. Birds represent an opportunity to include this ‘invisible fraction’ if each egg contains a zygote, but whether hatching failure is caused by fertilization failure versus prenatal mortality is largely unknown. We quantified fertilization failure rates in two bird species that are popular systems for studying evolutionary dynamics and found that overwhelming majorities (99.9%) of laid eggs were fertilized. These systems thus present opportunities to eliminate the invisible fraction from life-history data.

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