Mimus Saturninus Research Articles

How effective is camera trapping in monitoring grassland species in the southern Pampas ecoregion?

We assessed the efficiency of camera trapping in monitoring bird and mammal species in the grasslands of Tandilia Mountains by calculating the naïve occupancy, capture rate, and time to the first detection for each species. We compared the observed richness with the reported richness from online databases. We performed species accumulation curves to estimate the sampling effort necessary to detect bird species. We detected 50 bird and 15 mammal species. The top 5 bird species (Chalk-browed Mockingbird, Rufous-collared Sparrow, Rufous Hornero, Great Pampa-Finch, and Spotted Nothura) accounted for 48% of all detected individual birds, with naïve occupancy of 21-25% and mean times for the first detection between 6 and 9 days. The top 5 mammal species (Pampas fox, Large hairy Armadillo, European hare, Molina’s hog-nosed skunk, and Geoffroy’s cat) accounted for 81% of all detected individual mammals, with naïve occupancy of 32-77% and mean times for the first detection between 4 and 7 days. A sampling effort of 2 weeks was the optimal balance between effort and result qualities. We detected all the reported richness of mammals and half of the reported grassland-associated birds. We provide valuable information for future grassland species monitoring with camera trapping in Neotropical grasslands.

Co-parasitism in the face of predation: Effects of natural enemies on a neotropical mockingbird.

Co-parasitism is ubiquitous and has important consequences for the ecology and evolution of wild host populations. Studies of parasite co-infections remain limited in scope, with few experimental tests of the fitness consequences of multiple parasites, especially in natural populations. We measured the separate and combined effects of Philornis seguyi nest flies and shiny cowbirds Molothrus bonariensis on the fitness of a shared host, the chalk-browed mockingbird (Mimus saturninus) in Argentina. Using a two-factor experimental approach, we manipulated the presence of nest flies and cowbirds in mockingbird nests and assessed their effects on mockingbird haemoglobin levels, begging and provisioning rates, body size, and fledging success. We also monitored rates of nest predation in relation to parasitism by flies and cowbirds. Nest flies reduced the haemoglobin concentration, body size, and fledging success of mockingbirds, likely because mockingbirds did not compensate for parasitism by begging more or feeding their nestlings more. Cowbirds also reduced the fledging success of mockingbirds, even though they had no detectable effect on haemoglobin or body size. Nests with cowbirds, which beg more than mockingbirds, attracted more nest predators. There was no significant interaction between the effects of flies and cowbirds on any component of mockingbird fitness. The combined effects of nest flies and cowbirds were strictly additive. In summary, we show that nest flies and cowbirds both reduce host fitness, but do not have interactive effects in co-parasitized nests. Our results further suggest that predators exacerbate the effects of nest flies and cowbirds on their hosts. Our study shows that the fitness consequences of co-parasitism are complex, especially in the context of community-level interactions.

Mutualistic interaction network structure between bird and plant species in a semi-arid Neotropical environment

Mutualistic interactions between animals and plants are essential for ecosystem functioning, providing ecosystem services such as pollination and seed dispersal. The temporal dynamics of plant phenology and animal abundance, induced by seasonal variation in precipitation and resource availability, may influence the structure of animal-plant interaction network. In this paper, we analyzed the mutualistic network structure between birds and plants in a seasonally tropical dry forest in Brazil during the dry and rainy seasons. We recorded 160 interactions between 21 bird species and 11 plant species. In general, networks had low connectance (C = 26%), nestedness (wNODF = 27.54), and modular pattern (Qw = 0.33). Despite the number of interactions being higher in the rainy season, network parameters were consistent across the seasons and presented no explicit differences. However, the network connectance was slightly higher in the rainy season than in the dry season, while the specialization index was higher in the dry season than in the rainy season. Elaenia sp., Mimus saturninus, and Cyanocorax cyanopogon were the bird species that presented the highest number of links. On the other hand, Xiquexique gounellei, Cereus jamacaru, and Pilosocereus pachycladus were the most consumed plant species. The generalized pattern observed suggests that bird-plant interaction in Caatinga may be appropriate to the variable and irregular patterns found in dry forests. Our data reinforce the role of species of the Cactaceae family in maintaining bird communities in semiarid environments. Therefore, due to the high functional importance of those cacti species in influencing both the network stability and the species maintenance in the community, priority attention should be given to them in conservation programs.

New reports of parasitism by Synhimantus (Dispharynx) nasuta (Rudolphi, 1819) (Nematoda: Acuariidae) in wild birds in Brazil.

The aim of this study was to register the first occurrence of Synhimantus (Dispharynx) nasuta (Nematoda: Acuariidae) in some species of wild birds in Brazil. In addition, the aim was to deepen the knowledge about the morphology of this species through analysis using scanning electron microscopy. Nematodes were collected in wild birds of the species Turdus leucomelas, T. rufiventris, Mimus saturninus, Pitangus sulphuratus, Megascops choliba, Tyto furcata, and Falco sparverius. The morphological and morphometric data observed in the nematodes prove that these parasites are S. (D.) nasuta. This study also provides morphological data from light microscopy and scanning electron microscopy (SEM), as well as the morphometry of this nematode in each host species. Therefore, the current study confirms the first record of this nematode in F. sparverius and T. furcata in South America and, at the same time, these findings expand the host range of this parasite species worldwide, through the first records in M. choliba, M. saturninus, T. leucomelas and T. rufiventris.

Spatial segregation between the native Tropical mockingbird and the invader Chalk-browed mockingbird (Passeriformes: Mimidae) along a Neotropical natural-urban gradient

Spatial segregation between the native Tropical mockingbird and the invader Chalk-browed mockingbird (Passeriformes: Mimidae) along a Neotropical natural-urban gradient

Effects of the association between Mimus saturninus and Furnarius rufus on their foraging and alert behaviors

Effects of the association between Mimus saturninus and Furnarius rufus on their foraging and alert behaviors

Preferential Begging Responses of Shiny Cowbirds to the Conspecific Chatter Call

Avian brood parasites lay their eggs into the nests of other species, which incubate them and raise the chicks until their independence. Despite living their early weeks of life surrounded by heterospecifics, young brood parasites have the ability to recognize and associate to conspecifics after independence. It has been proposed that the initial conspecific recognition develops when a young parasite encounters a unique species-specific signal that triggers the learning of other aspects of the producer of the signal. For cowbirds (Molothrus spp.), this species-specific signal is hypothesized to be the chatter call. Young birds also could express auditory biases, which in some cases lead to discrimination in favor of conspecific songs. Therefore, the perceptual selectivity for chatters might be also present in nestlings. Our aim was to assess if nestlings of the shiny cowbird (M. bonariensis) present a preferential begging response to conspecific chatter calls. We evaluated if they respond more to the parasitic vocalization than host chicks and if they respond more to the chatter than to heterospecific nonhost calls. We tested shiny cowbird chicks reared by chalk-browed mockingbirds (Mimus saturninus) or house wrens (Troglodytes aedon) and host chicks, as control species. We randomly presented to 6-day-old chicks the following playback treatments: (1) conspecific chatter calls, (2) host calls, used as positive controls, and (3) nonhost calls, used as negative control. We measured if chicks begged during the playback treatments and the begging intensity. When responding to the playback of chatter calls, shiny cowbird chicks begged at a higher frequency and more intensively than host chicks. Shiny cowbird chicks reared by mockingbirds begged more intensively to playbacks of conspecific chatter calls than to host calls, while those reared by wrens begged with a similar intensity to playbacks of conspecific chatter and host calls. On the contrary, wren nestlings begged more intensively to playbacks of the wren call than to chatter calls. Mockingbird nestlings did not beg during any treatment. None of the three species begged during the playback of nonhost calls. Our results show that the chatter call produced a preferential begging response in cowbird nestlings, which may be the beginning of a process of conspecific recognition.

RECORD OF ABERRANT PLUMAGE IN Turdus rufiventris AND Mimus saturninus (AVES: PASSERIFORMES) IN SOUTHERN BRAZIL

Aberrant colorations are not considered unusual events in nature. Recently, several cases have been reported in articles and/or notes of scientific communication, thus contributing to the knowledge about these mutations in wildlife and reporting the affected species. Here, we bring two new records of wild birds with aberrant plumage in southern Brazil: one record of a leucistic Rufous-bellied Thrush (Turdus rufiventris) individual and the first record of progressive greying in the Chalk-browed Mockingbird (Mimus saturninus).

Street design in suburban areas and its impact on bird communities: Considering different diversity facets over the year

Several studies have shown that suburban areas have higher bird diversity than non-urban areas. Native vegetation cover, habitat complexity and socioeconomic variables of suburban areas have shown to influence bird richness and composition. However, few studies have explored the effect of street design on bird communities by analyzing different facets of diversity, such as taxonomic, functional and phylogenetic diversity. Moreover, few studies have explored bird-habitat relationships during an annual cycle. In this study, we analyzed total and native bird community differences between two street designs in a suburban area of Mar del Plata city (Argentina) during the breeding and non-breeding seasons. We surveyed streets and chicanes (street with a zigzag pattern), the latter being characterized by a smaller paved area and larger lawn cover than the former. Birds were counted along 100 × 50-m transects. Total bird taxonomic and functional diversity were higher in chicanes than in streets during both seasons, whereas bird richness was higher in chicanes than in streets during the non-breeding season. Native bird richness was higher in chicanes during both seasons, whereas native species diversity was higher in chicanes than in streets during the non-breeding season. Total and native evolutionary distinctiveness and native functional diversity did not vary between street designs or seasons. Total and native species composition were similar between street designs and seasons, but the Eared Dove (Zenaida auriculata), the Rufous Hornero (Furnarius rufus), the Chalk-browed Mockingbird (Mimus saturninus) and the Shiny Cowbird (Molothrus bonariensis) showed increased abundances in chicanes. The results suggest the importance of reducing paved road areas, with the consequent increase of vegetated areas and, therefore, of bird diversity in suburban areas. Our analysis highlights the need to conduct studies during an annual cycle for a better understanding of bird community dynamics in urban environments.

Variation in multicomponent recognition cues alters egg rejection decisions: a test of the optimal acceptance threshold hypothesis.

The optimal acceptance threshold hypothesis provides a general predictive framework for testing behavioural responses to discrimination challenges. Decision-makers should respond to a stimulus when the perceived difference between that stimulus and a comparison template surpasses an acceptance threshold. We tested how individual components of a relevant recognition cue (experimental eggs) contributed to behavioural responses of chalk-browed mockingbirds, Mimus saturninus, a frequent host of the parasitic shiny cowbird, Molothrus bonariensis. To do this, we recorded responses to eggs that varied with respect to two components: colour, ranging from bluer to browner than the hosts' own eggs, and spotting, either spotted like their own or unspotted. Although tests of this hypothesis typically assume that decisions are based on perceived colour dissimilarity between own and foreign eggs, we found that decisions were biased toward rejecting browner eggs. However, as predicted, hosts tolerated spotted eggs more than unspotted eggs, irrespective of colour. These results uncover how a single component of a multicomponent cue can shift a host's discrimination threshold and illustrate how the optimal acceptance threshold hypothesis can be used as a framework to quantify the direction and amount of the shift (in avian perceptual units) of the response curve across relevant phenotypic ranges. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

Utilização de poleiros artificiais por aves em áreas de restauração ecológica dos biomas Cerrado e Mata Atlântica no Brasil

Artificial perches are widely used in ecological restoration projects; however, the results of these works are yet to be summarized in a review. The goal of the present study was to describe the taxonomic structure of birds that utilized artificial perches, as well as determine the species of birds that most frequently utilized the perches in restoration areas of the Cerrado and Atlantic Forest biomes. We used secondary data obtained from a systematic review of literature available on digital sources. A total of 17 studies were obtained for the two biomes, 15 of which were analyzed. From these studies, 126 bird species were recorded, averaging 19.26 ± 8.30 SD species per study. Five species were categorized as frequent users of artificial perches (Pitangus sulphuratus, Tyrannus melancholicus, Mimus saturninus, Columbina talpacoti, and Tyrannus savana). These birds are predominantly generalist species, which disperse seed under the perches and this feeding habit of this group has implications for the restoration process. The large number of species that utilize artificial perches highlights the importance of these structures in supporting bird diversity, in addition to the promotion of bird ecosystem services.Keywords: nucleation, birdlife, ecosystem services, agroecosystems.

Parasitic egg rejection decisions of chalk-browed mockingbirds Mimus saturninus are independent of clutch composition.

Obligate avian brood parasites lay their eggs in nests of other host species, which assume all the costs of parental care for the foreign eggs and chicks. The most common defensive response to parasitism is the rejection of foreign eggs by hosts. Different cognitive mechanisms and decision-making rules may guide both egg recognition and rejection behaviors. Classical optimization models generally assume that decisions are based on the absolute properties of the options (i.e., absolute valuation). Increasing evidence shows instead that hosts' rejection decisions also depend on the context in which options are presented (i.e., context-dependent valuation). Here we study whether the chalk-browed mockingbird's (Mimus saturninus) rejection of parasitic shiny cowbird (Molothrus bonariensis) eggs is a fixed behavior or varies with the context of the clutch. We tested three possible context-dependent mechanisms: (1) range effect, (2) habituation to variation, and (3) sensitization to variation. We found that mockingbird rejection of parasitic eggs does not change according to the characteristics of the other eggs in the nest. Thus, rejection decisions may exclusively depend on the objective characteristics of the eggs, meaning that the threshold of acceptance or rejection of a foreign egg is context-independent in this system.

Breeding biology of Chalk-browed Mockingbird Mimus saturninus in a natural savanna of central Brazil

The Chalk-browed Mockingbird Mimus saturninus (Mimidae) is a common bird in savannas, grasslands, and farmlands, also occurring in urban areas. We studied its breeding biology in a Cerrado savanna inside a reserve at central Brazil, from 2003 to 2013. We monitored 74 nests, which were usually found in the more open phytophysiognomies of the Cerrado. The breeding season lasted from late August to late December. The nest is a cup built with twigs and generally placed on shrubs and small trees. Mean nest height above the ground was 1.3 ± 0.5 m (n = 73). Mean clutch size was of 2.9 ± 0.9 eggs (n = 63), ranging from one (possibly an incomplete clutch) to six eggs (possibly a communal nest). Incubation was asynchronous, the incubation period lasted 14.2 ± 0.9 days (n = 17 nests), and the nestling period lasted 14.1 ± 1.2 days (n = 21 nests). Nestling infestation by botfly larvae was common (60% of nests), but did not cause any nest loss. Its breeding season was similar to most birds of the Cerrado region, but its clutch size was larger. The Chalk-browed Mockingbird breeding biology in central Brazil is similar to that reported from the southern part of its distribution. The species is capable of multiple broods, has cooperative breeding and shows evidence of communal breeding, a rare behavior reported so far for Mimidae. The main difference between our study and those conducted with the Chalk-browed Mockingbird in Argentina, is the very low prevalence of brood parasites, demonstrating the importance of reserves to allow breeding with low brood parasitism rates.

Functional role of the invasive European Starling, Sturnus vulgaris, in Argentina

The introduction of exotic species may have severe effects on native ecosystems by disrupting communities and ecosystem services. Consequently, assessing the functional role of a species newly added to a community is an important task in order to identify native species at risk. In Argentina, the ecology of the invasive European Starling (Sturnus vulgaris) is poorly known and studies addressing its ecological role in bird communities are still lacking. We assessed the functional role of the European Starling by sampling bird communities across four vegetation types (Solanum grassland, Cynodon grassland, flood plain and forest patches) and making comparisons of body mass, and dietary and foraging traits of European Starling with native and other introduced bird species in east-central Argentina. The European Starling was functionally most similar to two widespread, generalist native passerines—the Bay-winged Cowbird (Agelaioides badius) and the Chalk-browed Mockingbird (Mimus saturninus)—and to the invasive House Sparrow (Passer domesticus), which together defined a functional group of terrestrial and foliage omnivores. European Starlings were more abundant in Solanum grasslands than in other vegetation types and showed significant vegetation-type overlap with functionally similar species. Moreover, abundance of European Starlings was positively correlated with bird abundance and diversity. Our results identify native species that are functionally equivalent to European Starlings, and, consequently, potentially subject to ecological impacts.

Inventario de aves del Barrio Centro de la ciudad de Luján, Buenos Aires, durante el poríodo no reproductivo

La conservación de la biodiversidad requiere del conocimiento previo sobre la distribución de los hábitats y de las especies silvestres que habitan en ellos. Conocer la diversidad ornitológica de las ciudades permite no solo conservar a las especies que habitan en ellas sino también a su entorno. El objetivo de este trabajo es presentar un inventario de la riqueza de aves que visitan y habitan las áreas verdes urbanas (AVU) del barrio centro de la ciudad de Luján (provincia de Buenos Aires) durante el periodo invernal. Se empleó el método de conteo por puntos de radio fijo, con una duración de 10 minutos en cada uno registrándose las especies observadas. Entre las 11 AVU se muestrearon 28 puntos, con 4 repeticiones en cada uno. Se registraron 29 especies distribuidas en 8 órdenes y 20 familias. Las familias mayormente representadas fueron: Columbidae (5 especies), Furnariidae (2 especies), Tyrannidae (2 especies), Turdidae (2 especies) y Thraupidae (2 especies). La especies más frecuentes fueron: Milvago chimango, Zenaida auriculata, Furnarius rufus, Pitangus sulphhuratus, Turdus rufiventris, Mimus saturninus y Passer domesticus. Se registraron tres especies exóticas: P. domesticus, Sturnus vulgaris y Columba livia. La mayor riqueza y frecuencia de especies se dieron en las AVU de mayor tamaño. Se plantea la importancia de conservar espacios verdes de gran tamaño dentro de las ciudades y realizar actualizaciones anuales del inventario de aves a través de programas de monitoreo sistemáticos. De esta manera, los datos recabados pueden ser utilizados como indicadores de calidad de los ecosistemas urbanos.

New host records of ticks (Ixodidae) infesting birds in an Atlantic Forest fragment in southeastern Brazil

Abstract We report new records for ixodid ticks in birds in an Atlantic Forest fragment, in the southeastern of the state of Rio de Janeiro, southeast Brazil. We collected 222 ticks: three females of Ixodes paranaensis and 40 larvae and 179 nymphs belonging to the genus Amblyomma, on 82 birds. The new records are: three semi-engorged females of Ixodes paranaensis collected on Cypseloides fumigatus, Apodidae; five nymphs of Amblyomma nodosum collected on Leucopternis lacernulatus, Geotrygon montana, Piaya cayana, Trogon viridis and Dysithamnus stictothorax; four nymphs of Amblyomma longirostre collected on Veniliornis maculifrons, Lepidocolaptes angustirostris, Machetornis rixosa and Tangara peruviana; two nymphs of Amblyomma calcaratum collected on Terenura maculata and Mimus saturninus; and five nymphs of Amblyomma tigrinum collected on Ramphocelus bresilius. Additionally, we also add tick records that have previously been reported from other fragments of the Atlantic Forest.

Experimental evidence for an antipredatory function of egg rejection behaviour in a common host of the brood-parasitic shiny cowbird

The rejection of foreign eggs is the most effective adaptation against brood parasitism in birds. Many hosts, however, show suboptimal responses towards parasitic eggs, which could reflect a compromise between the benefits and costs of egg rejection. Some large-sized hosts of the shiny cowbird (Molothrus bonariensis) accept any spotted parasite egg but reject a rarer pure white egg morph that occurs only in some parts of the parasite’s distribution. This behaviour is intriguing because it is not an effective defence against parasitism and recent evidences suggest that large-sized hosts could benefit from accepting cowbird eggs as this may dilute the risk of host egg losses at multiply parasitized nests. We studied whether rejection of pure white cowbird eggs can be driven by the increased predation risk of host nests parasitized with this conspicuous egg morph. We conducted a nest predation experiment using artificial clutches placed in natural, inactive nests of a large-sized host, the chalk-browed mockingbird (Mimus saturninus). Clutches consisted of two eggs resembling either one host plus one pure white cowbird egg, one host plus one spotted cowbird egg or two host eggs. Clutches with pure white eggs were more likely to be predated than those having either two host eggs or one host and one spotted cowbird egg, supporting an antipredatory function of egg rejection behaviour in mockingbirds. These results suggest that nest predation could operate as part of larger fitness trade-offs shaping host responses towards foreign eggs. Considering the role of nest predation in the studies of host rejection decisions would help to better understand the evolution and expression of antiparasite defences, especially when the hosts seem to behave suboptimally against costly brood parasitism. One major goal in avian brood parasitism research is to explain the evolution of host defences against parasite eggs and young. Some large-sized hosts of the shiny cowbird (Molothrus bonariensis) show an intriguing behaviour: they accept spotted cowbird eggs but reject a rare pure white egg morph that occurs only in some parts of the parasite’s distribution. Such behaviour provides little protection against parasitism, but it may serve as an antipredatory defence if conspicuous pure white eggs facilitate the detection of host nests to potential predators. Our study supports this idea by showing that pure white eggs increase the risk of nest predation compared to spotted host and cowbird eggs in a common large-sized host, the chalk-browed mockingbird (Mimus saturninus). These findings highlight the importance of considering the role of nest predation in the expression of hosts’ strategies against parasitism.

Molecular tracking of individual host use in the Shiny Cowbird - a generalist brood parasite.

Generalist parasites exploit multiple host species at the population level, but the individual parasite's strategy may be either itself a generalist or a specialist pattern of host species use. Here, we studied the relationship between host availability and host use in the individual parasitism patterns of the Shiny Cowbird Molothrus bonariensis, a generalist avian obligate brood parasite that parasitizes an extreme range of hosts. Using five microsatellite markers and an 1120‐bp fragment of the mtDNA control region, we reconstructed full‐sibling groups from 359 cowbird eggs and chicks found in nests of the two most frequent hosts in our study area, the Chalk‐browed Mockingbird Mimus saturninus and the House Wren Troglodytes aedon. We were able to infer the laying behavior of 17 different females a posteriori and found that they were mostly faithful to a particular laying area and host species along the entire reproductive season and did not avoid using previously parasitized nests (multiple parasitism) even when other nests were available for parasitism. Moreover, we found females using the same host nest more than once (repeated parasitism), which had not been previously reported for this species. We also found few females parasitizing more than one host species. The use of an alternative host was not related to the main hosts' nest availability. Overall, female shiny cowbirds use a spatially structured and host species specific approach for parasitism, but they do so nonexclusively, resulting in both detectable levels of multiple parasitism and generalism at the level of individual parasites.

New data on the taxonomy and distribution of ten Neotropical chewing lice of the genus Myrsidea (Phthiraptera: Menoponidae), including the description of a new species.

The new species Myrsidea alexanderi is described and illustrated ex Pheugopedius maculipectus (Troglodytidae) from Honduras. Redescriptions and illustrations are given for both sexes of Myrsidea chiapensis ex Calocitta formosa from Costa Rica, and the male of M. dissimilis ex Progne chalybea from Brazil. Also, seven other previously known species or subspecies of the louse genus Myrsidea are recorded and discussed from passerine birds of the Neotropical Region, as follows: Myrsidea antiqua, Myrsidea balteri, Myrsidea diffusa, Myrsidea nesomimi borealis, Myrsidea paleno, Myrsidea psittaci and Myrsidea serini. Our data increase knowledge of intraspecific morphological variability within these species, and also of their host and geographical distribution. New host-louse associations are: Agelaioides badius for M. psittaci; Basileuterus culicivorus and Myiothlypis leucoblephara for M. paleno; Mimus saturninus for M. nesomimi borealis; and Icterus dominicensis and Molothrus rufoaxillaris for Myrsidea sp.

Nest environment modulates begging behavior of a generalist brood parasite

In young birds, the intensity of the begging signal varies according to the chick’s internal condition (i.e., hunger or nutritional state) but may be additionally modulated by the external conditions experienced in the nest (e.g., nestmate competition or feeding success). Flexibility of begging in response to nest environment should be especially beneficial for the chicks of generalist brood parasites, which encounter diverse brood conditions depending on the host nest in which they are reared. We investigated variability in the begging behavior of an extreme generalist brood parasite, the shiny cowbird ( Molothrus bonariensis ). We compared visual and vocal begging variables of cowbird young of 5 days of age reared in nests of 2 common hosts, one smaller (house wren, Troglodytes aedon ) and one larger (chalk-browed mockingbird, Mimus saturninus ) than the parasite. Cowbird chicks were standardized for short-term hunger prior to recording and were similar in mass/condition in each host, but nevertheless begged more intensely in mockingbird than house wren nests, as indicated by increased stretching of the neck, lower latency to beg, increased time spent begging per bout and greater call rate. These results are consistent with young cowbirds adjusting their begging intensity based on the intrabrood competition of a given host, independent of need, an adaptability that likely contributes to their success as parasites utilizing diverse host species.