Zenaida Auriculata Research Articles

Contrary to phylogenetic predictions, crown coloration of the Eared Dove is not regulated by sex hormones

The mechanisms regulating plumage coloration appear to be phylogenetically conserved in avian species: the plesiomorphic character state is estrogen-dependent regulation, while testosterone, luteinizing hormone, and non-hormonal control are derived states. Limited data exist on the underlying regulatory processes of sexual dichromatism in the Eared Dove ( Zenaida auriculata (Des Murs, 1847)). Since the Columbiformes order is close to basal branches, we hypothesized that estrogen and testosterone play a central role in the regulation of crown plumage coloration in the Eared Dove. To test this, we subjected adult males to a forced molt accompanied by an exogenous increase of estradiol and testosterone to determine whether the presence of these hormones during molting modified the spectrophotometric characteristics of the plumage. No significant differences were found between treatments and controls in the colorimetric variables hue, ultraviolet saturation, and brightness. Similarly, the avian visual model showed no perceptible changes in chromatic and achromatic signals in the individual male adults. We also analyzed the effects of estrogen and testosterone on the growth speed of the new feathers. The hormone-treated groups increased in the speed of molting compared to the control group. These results suggest that the Eared Dove is an exception to basal branch models: rather than regulating coloration, sex hormones speed up the growth of the new feathers.

Dinámica estacional de la comunidad de aves en parques urbanos y cementerios de Buenos Aires, Argentina

Urban green spaces play a fundamental role in bird conservation in cities. Although the role of urban parks in conserving bird diversity has been explored on a global scale, the analysis of the role of cemeteries has been scarcer. This study aimed to describe and compare the seasonal dynamic of different components of avian taxonomic diversity and composition in two types of urban green areas, parks and cemeteries, in the Autonomous City of Buenos Aires (Argentina). Birds were counted at fixed counting points of 100 m radius in three parks and three cemeteries, and rarefaction curves were used to compare their taxonomic diversity between parks and cemeteries during the breeding and non-breeding seasons. In general, bird diversity (measured as species richness and Shannon and Simpson diversity index) was higher in cemeteries than in parks and during the breeding season, showing greater variation in cemeteries. Bird composition changed between seasons, with Zenaida auriculata being the most common species during the breeding season and Myiopsitta monachus the most abundant during the non-breeding season. However, the composition of the avian community (the most common and abundant species) was similar between parks and cemeteries. Our results suggest that cemeteries are green spaces of great importance since they add heterogeneity to the urban landscape, providing a greater diversity of micro-habitats capable of housing a higher number of species than parks. The higher degree of seasonal variation in the bird community in cemeteries suggests that these habitats help maintain the natural seasonal dynamics.

Field Availability and Avoidance of Imidacloprid-Treated Soybean Seeds and Cotyledons by Birds.

Treated seeds and their cotyledons can present a toxicological risk to seed-eating birds. To assess whether avoidance behavior limits exposure and consequently the risk to birds, three fields were sown with soybeans. Half of the surface of each field was sown with seeds treated with 42 g/100 kg seed of insecticide imidacloprid (T plot, treated) and the other half with seeds without imidacloprid (C plot, control). Unburied seeds were surveyed in C and T plots at 12 and 48 h post-sowing. Damaged seedlings were surveyed in C and T plots at 12 days post-sowing. The abundance and richness of birds was surveyed at the field level (without distinguishing between C and T plots) before, during, and after sowing, and 12 days post-sowing. Unburied seed density was higher in the headlands of the T plots than in the C plots, but did not differ between 12 and 48 h. The damage to cotyledons of seedlings was 15.4% higher in C plots than in T plots. The abundance and richness/ha of birds that eat seeds and cotyledons were lower after sowing, indicating a deterrent effect on birds by sowing imidacloprid-treated seeds. Although the variation in seed density over time does not allow solid conclusions to be drawn about the avoidance of seeds treated by birds, the seedling results suggest an aversive effect of imidacloprid-treated soybeans on birds. The dominant species was the eared dove (Zenaida auriculata), whose risk of acute poisoning by imidacloprid in soybean seeds and cotyledons was low, according to its toxicity exposure ratio, foraged area of concern, and foraged time of concern. Environ Toxicol Chem 2023;42:1049-1060. © 2023 SETAC.

Evaluation of lead exposition length on the liver and intestinal histoarchitecture of eared dove (Zenaida auriculata).

Lead (Pb) is a metal that can produces irreversible damage in living organisms. Some studies had reported that Pb produces histophysiological alterations in the digestive system (mainly liver) of birds; however, the effect of this metal on small intestine has not been fully examined. Additionally, little information is available on Pb disturbances in native birds of South America. The present study aimed to evaluate the effect of different Pb exposure times on blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity and on the histological and morphometric characteristics of the digestive system (liver and proximal intestine) of eared doves (Zenaida auriculata). A decrease of the blood δ-ALAD activity, dilatation of blood vessels and leukocyte infiltrates in intestinal submucosa and muscular layers, and reduction of the enterocyte nuclear diameter and Lieberkühn crypts area were observed. In liver were noted steatosis, proliferation of bile ducts, dilated sinusoids, leukocyte infiltrates, and melanomacrophage centers. The portal tract area and the thickness of the portal vein wall were increased. In conclusion, the results showed that Pb produces histological and morphometric alterations on the liver and small intestine according to the exposure time, which should be considered when the dangerousness of environmental pollutants is evaluated in wild animals.

Annual molt period and seasonal color variation in the Eared Dove´s crown.

Molting is an important process in which old and worn feathers are exchanged for new ones. Plumage color is determined by pigments such as carotenes, melanin and by the ultrastructure of the feather. The importance of plumage coloration has been widely studied in different groups of birds, generally at a particular time of the year. However, plumage coloration is not static and few studies have addressed the change in plumage color over time and its relationship to reproductive tasks. The Eared Dove (Zenaida auriculata, Des Murs, 1847) has a melanistic coloration with sexual dichromatism in different body regions. The Eared Dove´s crown is the most exposed body region during the bowing display. Our objective was therefore to accurately determine the molting period of the crown feathers and study the seasonal variation in their coloration in females and males. Our findings indicate a molting period of 6 months (January to June). The new feathers are undergoing changes in their coloration from July to December. During that period we apply an avian vision model then enabled us to reveal a seasonal variation in the coloration of the crown feathers in both sexes, as given by a change in the chromatic distances. The highest values in the chromatic distances towards the reproductive period are given by a change in the UV-violet component of the spectrum, indicating changes in the microstructure of the feather. This change in crown coloration towards the breeding season could be linked to reproductive behaviors.

Blood feeding patterns of the Culex pipiens complex in equestrian land uses and their implications for arboviral encephalitis risk in temperate Argentina.

Blood feeding patterns of mosquitoes are a key component in the dynamics of arboviral encephalitides transmission. In temperate Argentina, the members of the Culex pipiens complex include Cx. pipiens molestus, Cx. quinquefasciatus and their hybrids. To characterize their blood feeding patterns, adult resting mosquitoes were collected monthly during the warm season in urban and rural equestrian fields. The availability of birds and domestic mammals per site was characterized. The blood source and the complex member were successfully identified for 89 specimens using PCR. Blood of 19 vertebrate species was isolated including four mammals (most common feeds from dog, Canus lupus 19% of the blood meals; and horse, Equus caballus 18%) and 15 birds (picazuro pigeon, Patagioenas picazuro 11%; eared dove, Zenaida auriculata 10%; chicken, Gallus gallus 9%). The Forage Ratio (FR), calculated as the proportion of feeds taken from a given host species with respect to that host availability in the environment, suggested preference for dog by all members of the complex (FR ≥4.5). On the contrary, FR values suggested avoidance for horse by Cx. quinquefasciatus and the hybrid (FR ≤0.8), and a use proportional to its abundance by Cx. pipiens molestus (FR=1.1-1.2 in urban and rural sites, respectively). FR values suggesting preference were obtained for avian species of the orders Passeriformes (7 species in total) and Columbiformes (5) by all members of the complex (FR ≥ 3.3), whereas values for monk parakeet (Myiopsitta monachus, Psiitaciformes) suggested avoidance by Cx. quinquefasciatus in urban sites (FR=0.4) and by Cx. pipiens molestus in rural sites (FR=0.3) but not in urban sites (FR=1.4). A mammal-bird index (MBI, from -1 all avian to +1 all mammalian blood meals) was calculated for each member of the complex and urbanization category. Values were negative for Cx. quinquefasciatus (MBIurban = -0.60, MBIrural = -0.33) and positive for Cx. pipiens molestus (MBIurban = 0.20, MBIrural = 0.60), indicating a higher proportion of feeds taken on birds and mammals, respectively, regardless of the urbanization category. In temperate Argentina, the members of the Cx. pipiens complex fed both on horses and on birds, thus representing a real risk of transmission of arboviral encephalitides from avian enzootic cycles to horse epizootics.

Oil-con hybrids as a potential tool to prevent eared dove damage to sunflower crops

Abstract Eared doves (Zenaida auriculata) cause significant economic damage to mature sunflower in Argentina. Empirical evidences indicate that some sunflower hybrids (e.g. confectionary and stripped oilseed) might be less susceptible to bird damage than others (e.g. black oilseed). However, these less susceptible hybrids could imply a trade-off between damage reduction and oil content on the seeds. In this work, we investigated the potential of a new oil-con hybrid types (OC: oilseed × confectionary cross) as a tool to prevent eared dove damage to sunflower crops. We compared the performance (damage values), morphological characteristics and nutritive quality of this hybrid compared to other three standard sunflower hybrids (BO: black oilseed, SO: striped oilseed, and CON: confectionary), both in the field and in cages. In both tests, doves significantly selected BO and SO hybrids over CON and OC hybrids. The OC hybrid was not selected, despite its high nutritional value. Results suggest that achene size could be an important morphological trait influenced eared dove selection of hybrids, independently of other seed characteristics. Based on these results, the OC hybrid tested in this study seems to be a promising tool for preventing eared dove damage to sunflower in Argentina.

Evaluación de la nicarbazina como herramienta de manejo para disminuir los daños por paloma torcaza (Zenaida Auriculata)

Eared doves (Zenaida auriculata) cause losses in confined cattle production and damage in agricultural crops. Because to population size and limitations in the current available techniques, contraceptive methods appear as a complementary alternative to reduce damage in Uruguay. The objective of this thesis was to study the feasibility of nicarbazin as a contraceptive for eared doves. The acceptance of three presentations of bait (0.5 % nicarbazin) was evaluated: OvoControlS® pellets; mixture of OvoControlS® with cracked corn; and cracked OvoControlP® pellets. Intake of each presentation per bird and per day was measured in 10 eared doves. Cracked OvoControlP® was the only formulation with a weekly average consumption greater than 1,0 g/dove/day. Later, the nicarbazin dose to significantly reduce reproduction in 11 pairs of doves was determined at the aviary. Three experimental phases were used: pre-treatment (reproductive cycle before contraceptive was supplied), treatment (cycle under the effect of nicarbazin) and recovery (cycle after interrupting the product). Bait intake per day (g/pair) and reproductive variables were recorded. A 62 % statistical reduction in the number of viable eggs and successful fledgling was found in the treatment phase vs. pre-treatment. This was reversed after stopping the intake of the product, since there were no statistically significant differences in the number of eggs between pre-treatment and recovery. The average consumption of bait per day in the pairs that produced zero or one fledgling was significantly higher than pairs that had two fledglings in the treatment. Finally, a bait management system was established and its efficiency was evaluated to supply it to eared doves in two farms with cattle raised under confinement. We worked with two experimental phases offering the feed in bait stations (EDC): pre-treatment (pelleted poultry ration mixed with wheat) and treatment (a contraceptive and wheat mix). Number of birds in EDC and food consumption were evaluated. The number of eared doves in the EDC was significantly higher than individuals from other bird species. The contraceptive intake per dove in both experiments was 0.19 and 0.12 g/dove/day, not reaching the minimum dose necessary to cause an effect on reproduction of the specie. We conclude that nicarbazin is an effective contraceptive for eared doves. Research should continue in the development of contraceptive bait, evaluation in nesting site and an integrated bird management plan.

Territorial expansion of Zenaida auriculata (Aves: Columbidae) in the Brazilian Amazon

ABSTRACT Birds are considered bioindicators of environmental quality because they are sensitive to environmental changes. The eared dove (Zenaida auriculata) is associated with open areas, has low sensitivity to environmental changes and is widely distributed in Brazil, although it is not typically found in the Amazon region. We analyzed the biogeographic expansion of this species in the Brazilian Amazon through searches carried out on digital citizen science platforms. The records of Z. auriculata were related with the area of accumulated deforestation in the biome. We identified 804 records of Z. auriculata in the Brazilian Amazon, of which 259 were in areas where its occurrence had been previously unknown. We show that the species has been expanding its geographic distribution, clearly overlapping with deforested areas.

Avoidance of neonicotinoid-treated seeds and cotyledons by captive eared doves (Zenaida auriculata, Columbidae)

Farmland birds can be exposed to neonicotinoids through the ingestion of treated unburied seeds and cotyledons. The aim of this study was to evaluate the avoidance of sorghum with imidacloprid, clothianidin or thiamethoxam, soybean with imidacloprid, and soybean cotyledons with imidacloprid or thiamethoxam on eared doves (Zenaida auriculata). Doves were fed with test food (untreated and neonicotinoid-treated sorghum, soybean or soybean cotyledons) and maintenance food (seed mix) for 3–5 days to study the repellency (primary repellency and conditioned aversion) and anorexia caused by neonicotinoid-treated food, followed by a 7-day period on maintenance food to study the persistence of the anorexic effect after neonicotinoid exposure. Immediately afterward, the same doves were exposed to treated test food during a second period of 3–5 days to study the potential reinforcement of food avoidance. Finally, doves were fed with untreated test food to test the capacity of the pesticide to induce conditioned food aversion against untreated food in subsequent encounters. Intoxication signs and differences of body weight were determined. With sorghum, the three neonicotinoids produced a decrease in the consumption of treated seeds by >97% compared to control birds. However, this was not enough to prevent the death of 3/8 and 1/8 of the doves exposed to imidacloprid and clothianidin, respectively. Anorexia was clearly observed with neonicotinoid-treated sorghum. The birds did not avoid the untreated sorghum after exposure to the treated sorghum, indicating that avoidance is not generalized to the type of food without an associated sensory cue. The results obtained with soybean seeds and cotyledons were less conclusive because captive doves hardly consumed these foods, even without neonicotinoid treatment. The avoidance of sorghum seeds treated with neonicotinoids was insufficient to prevent poisoning and death of eared doves.

CONTRIBUTION OF INFORMAL GREENSPACE TO BIRD CONSERVATION IN CITIES: A COMPARATIVE STUDY ON THE DIVERSITY OF BIRD COMMUNITIES IN VACANT LANDS, URBAN PARKS AND RESIDENTIAL AREAS

Vacant lands are part of the informal greenspace and could maintain native fauna in urban ecosystems. To provide scientific evidence that promotes bird conservation in cities, we compared different bird community attributes among vacant lands, urban parks, and residential areas in the city of Santiago de Chile. For this, we estimated taxonomic diversity in the three land uses, investigated the species richness and abundance (total and native, including three trophic guilds: granivores, insectivores and omnivores) among land-use types, and evaluated the influence of habitat variables on bird species richness and abundance recorded at sites. We found that vacant lands supported a diverse, with low species dominance, species rich and abundant bird community, comprised mainly by native granivorous and insectivorous birds. In contrast, birds with generalist diet (omnivores) reached high abundances in urban parks and residential areas. While parks and residential areas were dominated by a single omnivore species (Turdus falcklandii and the exotic Passer domesticus, respectively), in vacant lands a set of native species reached high abundances. They included granivorous birds (Sicalis luteola, Zenaida auriculata y Zonotrichia capensis) and insectivorous birds (Tachycineta meyeni y Anthus correndera). Sites with larger cover of herbaceous plants exhibited greater richness and abundance of native birds. In addition, sites with larger proportion of their area covered by bare ground exhibited greater abundance of native birds. Our results demonstrate that vacant lands maintain high bird diversity, as well as a high species richness and abundance of native birds with specialized diets (granivores and insectivores), offering new opportunities to conserve biodiversity in cities.

Choroid plexus papilloma in a free ranging eared dove (Zenaida auriculata)

Choroid plexus tumors (CPT) are rare neoplasms and histologically classified as choroid plexus papilloma (CPP), atypical choroid plexus papilloma (APP), and choroid plexus carcinoma (CPC). These neoplasms have been described in humans, domestic animals (canine, feline, equine, caprine) and some wild animals (cetaceans and Psittacidae birds). To our best knowledge, herein we report the first CCP in a free-ranging eared dove (Columbiformes; Zenaida auriculata, de Murs 1847). Histologically, the ventricle was dilated, with a papillary proliferation (arboriform pattern) in topography of CP. The neoplasm was well-differentiated, composed by a single layer of cuboidal cells, anchored in a delicate fibrovascular stroma. The neoplastic cells exhibited moderate stroma, with well-defined borders and round nuclei, with vesicular chromatin and inconspicuous nucleoli. Mitotic activity was low (<1 mitosis per 10 high-power fields). Immunohistochemistry for cytokeratin markers (AE1/AE3 antibody) were implemented, however, both neoplastic cells and normal epithelial tissues do not show immunoreactivity.

Local and landscape features of wooded streets influenced bird taxonomic and functional diversity

Wooded streets diminish the negative consequences of urban growth on biodiversity. However, bird use of wooded streets has been little studied, in most cases analyzing bird species richness and abundance in developed countries. In this study, we analyzed the relationship between environmental variables of wooded streets of Buenos Aires City (Argentina) and bird taxonomic and functional diversity as well as species and functional trait composition. We placed 26 100m × 50m transects within the wooded streets of the urban center. Bird surveys were performed during the austral spring and summer. Species richness, Pielou’s evenness, Shannon index, Functional dispersion (FDis), and species and functional trait composition were analyzed. Taxonomic and functional diversity were negatively related to pedestrian and motorized vehicle traffic. On the other hand, taxonomic diversity was related positively to streets with varied tree heights. Native taxonomic diversity and functional diversity increased near green areas. The coverage of high buildings was negatively related to the native taxonomic diversity. Bird species associated with humans, such as the Rock Dove (Columba livia) and the Eared Dove (Zenaida auriculata) increased their abundances in sites with high pedestrian and motorized traffic. The House Wren (Troglodytes aedon), the Baywinged Cowbird (Agelaioides badius), and the Red-bellied Thrush (Turdus rufiventris) were positively related to varied tree heights. Birds that feed on the ground and the undergrowth were negatively associated with the coverage of high buildings. It is imperative to preserve green areas and to control motorized vehicle traffic in order to improve the environmental quality of wooded streets for supporting bird diversity.

Window Collisions by Birds in Brazil: Epidemiologic Factors and Radiographic and Necropsy Assessments.

Birds are among the most visually proficient group of animals on the planet; however, their inability to visualize and discriminate translucent glass structures results in an extreme number of deaths worldwide from high-speed collisions. Despite reports of avian glass collisions in North America, only a few studies have been developed to understand this problem in South America, and none evaluated radiographic and postmortem findings. One hundred cadavers were examined radiographically and postmortem, and data from 186 collision reports were analyzed for seasonality (website and manual reports and cadavers). A total of 34 different species of birds within 22 families were evaluated for this study, with the rufous-bellied thrush (Turdus rufiventris; n = 12), eared dove (Zenaida auriculata; n = 12), and ruddy ground dove (Columbina talpacoti; n = 10) being the most common species. Only 6 (27.7%) migratory species were reported: Sick's swift (Chaetura meridionalis), small-billed elaenia (Elaenia parvirostris), Black Jacobin (Florisuga fusca), Great kiskadee (Pitangus sulphuratus), Double-collared seedeater (Sporophila caerulescens), and Creamy-bellied thrush (Turdus amaurochalinus). Males (51) were more frequently reported than females (5), and 50.1% of the males had active gonads. Sex was unable to be determined in 44 birds. The most common radiographic lesion, noted in 16 of 82 (19.5%) animals, was loss of coelomic definition, suggestive of hemorrhage. Prevalent postmortem findings included skull hemorrhages (58/75, 77.3%) and encephalic contusions (47/73, 64.4%), followed by coelomic hemorrhages (33/81, 40.7%). Most of the window collisions (61/186, 32.8%) occurred during spring, the most common breeding season of avian species in Brazil. Cranioencephalic trauma was identified as the primary cause of mortality associated with birds flying into glass windows. Migration does not appear to be the main predisposing factor for window collisions by birds in Brazil. Increased activity and aggression related to breeding season, especially in males, may be a more important predisposing factor for window collision accidents.

FEEDING HABITS OF THE STYGIAN OWL (ASIO STYGIUS) AND THE SHORT-EARED OWL (A. FLAMMEUS) IN THE SOUTHWEST OF BOGOTÁ SAVANNA, CUNDINAMARCA, COLOMBIA

This study quantitively compares the diets of the Stygian Owl (Asio stygius) and the Short-eared Owl (A. flammeus) in the south-west of the Bogotá Savanna, Colombia. We identified 130 prey items from 111 A. stygius pellets and 579 prey items from 149 A. flammeus pellets. In terms of the numbers of preys, the diet of A. stygius consisted of the following: 88.1% birds, mainly pigeons, rails and cuckoos; and a smaller proportion of beetles (11.4%). In the diet of A. flammeus, insects were the most frequent prey item (59.8%), followed by rodents (39.8%), and birds (0.5%). In terms of biomass contribution, the main preys in the diet of A. stygius were Eared Doves (Zenaida auriculata) (54%) and Purple Gallinules (Porphyrio martinica) (19.3%), while the diet of A. flammeus consisted mainly of House Mice (Mus musculus) (65.2%). Diet diversity varied between the owl species: A. flammeus was more selective in its hunting habits, while A. stygius was more of an opportunistic predator. It is important to quantify the ecosystem services these owls provide not only by controlling M. musculus, Z. auriculata, and Shiny Cowbird (Molothrus bonariensis) populations, which can affect human well-being and threatened species populations, but also through secondary seed dispersion and birdwatching opportunities.

Bird Taxonomic and Functional Diversity in Three Habitats in Buenos Aires City, Argentina

Urban green spaces (UGS), such as parks and wooded streets, are open areas with vegetation that provide sustainability to urban areas. However, their role in conserving bird diversity in neotropical cities has scarcely been analyzed. The aim of this study was to analyze the variation of bird assemblages in non-wooded streets, wooded streets, and parks in Buenos Aires City, Argentina. We compared the taxonomic and functional diversity between these habitat types. We selected five non-wooded streets, five wooded streets, and five parks in the city. Bird surveys were performed in 100 m long and 50 m wide transects. We found that taxonomic diversity had the greatest value in the parks, followed by wooded streets, and then the non-wooded streets. Functional diversity was similar between habitats. The taxonomic and functional composition changed between habitats. Non-wooded streets were dominated by the Rock Dove (Columba livia) and the Eared Dove (Zenaida auriculata), whereas parks had the highest abundance of the Picazuro Pigeon (Patagioenas picazuro) and the Rufous-bellied Thrush (Turdus rufiventris). Non-wooded streets were dominated by omnivorous and granivorous species, whereas parks had a higher abundance of herbivorous and frugivorous species. The positive association between UGS and bird diversity highlights the role of UGS as biodiversity conservation sites in neotropical cities.

Population responses of pest birds across a forest cover gradient in the Chaco ecosystem

Industrial agriculture can trigger an increase in abundance of some bird species, promoting the emergence of pests, causing damage to crops and economic loss for farmers. Even though there are different strategies to control pest birds (chemicals, hunting, repellents, etc), in general they are inefficient. Moreover, these strategies can threaten non-target species, and toxic substances can be bioaccumulated in the food chain of wildlife animals. An alternative strategy (or at least complementary) could be the design of agricultural landscapes that balance natural habitats and crop production areas in a way that would not trigger the abundance increases of potential pest birds. We assessed population trends of four bird species (potentially agricultural pests) across a forest cover gradient, and consequently, a gradient of agricultural cover expansion, at a landscape level. The study was conducted in the Chaco forest, one of the most threatened ecosystems worldwide due to agricultural expansion. Studied species were Eared Dove (Zenaida auriculata), Spot-winged Pigeon (Patagioenas maculosa), Picazuro Pigeon (Patagioenas picazuro) and Monk Parakeet (Myiopsitta monachus), and their populations are often considered as the major pest birds for agriculture in several areas of Argentina and in other countries of South America. Abundances of birds species were measured in focal sites (forest patches) and the percentage of forest cover was estimated within buffers of 2000 m radius surrounding each site. A total of 12 local landscapes were surveyed. Results show that population responses (i.e. changes in abundance) to the gradient of forest cover were idiosyncratic. The main result shows that relative abundance of Eared Dove, the most abundant species, was triggered when landscapes had less than 16% of forest cover: landscapes with low forest cover (less than 10%) contained six times the relative abundance of Eared Dove than landscapes with a high percentage of forest cover (close to 100%). We propose that as pest birds in agroecosystems are a problem at the landscape or regional scale, solutions should be thought at such scale. In this context, landscapes in the region should conserve more than 16% of forest cover to attempt to control one of the most abundant pest bird species of South America.

Repellency, Anorexia and Aversion by Neonicotinoid-Treated Seeds and Cotyledons on Captive Eared Doves

Repellency, Anorexia and Aversion by Neonicotinoid-Treated Seeds and Cotyledons on Captive Eared Doves

Raptors, doves and fragmented landscapes: Overabundance of native birds elicit numerical and functional responses of avian top predators

The replacement of natural habitats by fields destined for agricultural-livestock production causes changes in species composition. Some species benefitting from these changes can become more abundant. Increased populations can alter trophic webs. In the center of Argentina, populations of the native eared dove (Zenaida auriculata) have increased significantly in several provinces to such an extent that the species has been declared a pest. In 2014, 20 transects were sampled monthly to determine spatial and temporal abundance fluctuations of two raptor species, the crested caracara (Caracara plancus) and the black-chested buzzard eagle (Geranoaetus melanoleucus) to increases in the population of eared doves. The diet of these birds of prey was determined over 10 years, between 2003-2007 and 2010-2015. The monthly average (± SD) of crested caracaras and black-chested buzzard eagles was 97.75 (± 33.6) individuals and 3.91 (± 3.0) individuals, respectively. The monthly average of eared doves during surveys was 63,460 (± 113,497) individuals. Although both raptor species strongly rely on eared doves as their main prey, only black-chested buzzard eagle's trophic niche breadth was determined by the presence of this prey by having a potential functional response. The crested caracara, by contrast, could show a numerical response to increase of eared dove abundance that was not evident with the black-chested buzzard eagle. Anthropogenic disturbances and habitat fragmentation are the main drivers of eared dove overabundance, whose populations can cause changes in the composition and structure of these two raptor communities and consequently disturb ecosystem processes.

NEW RECORDS OF BIRDS WITH ABERRANT PLUMAGE IN RIO GRANDE DO SUL, SOUTHERN BRAZIL

We present here six new cases of birds with aberrant coloring in the state of Rio Grande do Sul, Brazil. Records were made via non-systematized field activities. We suggested Progressive Greying in Zenaida auriculata, Turdus rufiventris, Leptasthenura setaria, Molothrus bonariensis and for Sporophila collaris a case of Dilution – pastel. The study contributes with new informations about chromatic anomalies in birds’ plumages in Southern Brazil, since these cases must be divulged in specialized literature.