Ornitología Neotropical

Avifauna Neotropical: ecología y conservación

Juan F Freile — 2024-06-14

BIOLOGÍA REPRODUCTIVA DEL CHINCHERO ENANO O CHINCHERO EXCAVADOR XIPHORHYNCHUS FUSCUS

Alejandro Bodrati — 2024-03-17

Despite recent advances, the knowledge scarcity on Furnariidae forest species reproduction continues to bias ideas and limit the understanding of avian life history. We studied the reproductive biology of the Lesser Woodcreeper (Xiphorhynchus fuscus; Dendrocolaptinae), which nests in tree cavities, to contribute observations toward ideas about evolution and ecology. In the Atlantic Forest of Argentina (2007–2022), we inspected 26 nests (total: 333 visits), color-banded nine adults, conducted 180 h of focal observations at 11 nests, and analyzed patterns of nest survival and parental care using linear models in R. Lesser Woodcreepers laid two or three white eggs (mean±SE = 2.8±0.1; N = 16) on a bed of bark flakes. One adult (possibly female) carried out construction, incubation, feeding, and nest hygiene, but we frequently observed a second adult (possibly male) singing from 'preferred' perches, sometimes approaching the nest tree in response to alarm calls from the nest. Attending adults brought bark to their nests throughout incubation (19 days) and occasionally during nestling (21 days; range: 20–23). In the absence of adults, eggs and young nestlings were left covered with bark. Nest attention (daytime percentage an adult was inside the cavity) was 63±3% during incubation, fell to 38±9% in the first 4 days after hatching, and approximately 0% after nestlings were 10 days old and had open pin feathers. Nestlings were fed almost exclusively arthropods, and the feeding rate increased as brooding declined. Nest survival was 0.984 (95% CI: 0.970–0.992) daily or 0.50 (0.26–0.70) for the nesting period. For four of six broods, when nestlings fledged, a second adult (possibly a male) participated minimally. Our observations cover the mating system and division of parental care in Furnariidae, the advantages of covering eggs and nestlings, and the possibility that males increase parental care during the vulnerable fledgling stage.

BREEDING BIOLOGY OF THE LOGGERHEAD SHRIKE LANIUS LUDOVICIANUS IN CENTRAL MEXICO

Octavio Soto Rojas — 2024-03-17

The Loggerhead Shrike Lanius ludovicianus has an exceptionally broad distribution in North America, with the southernmost populations found in central Mexico. The species has experienced severe declines throughout its range, and thus, is of conservation concern, particularly in USA and Canada. Life history data is scarce for Mexico, where both resident and migratory populations are found. In this study we provide information on the breeding biology of a population of Loggerhead Shrikes near the southern limit of its distribution in central Mexico. Based on data from 70 nests over three breeding seasons (2007–2009), we estimated the average nest density as 0.85 nests/ha with most nests built in mesquite trees Prosopis laevigata. Average clutch initiation date was March 28, with variation among years. The breeding period averaged 3.5 months, starting at the end of February, and extending to early June. The laying period averaged 4.6 days, incubation averaged 18 days, and the average brooding period 16.6 days, for a total average of 39.2 days from egg laying to the end of brooding. Clutch size averaged 4.1 eggs (range 2–5) with a mode of four eggs. The nesting success for the three years combined was 64.3% (range 54.5–68.9%). Daily survival rate was estimated to be 0.749 using logistic exposure. The average number of fledglings at successful nests was 1.5. Predation was the main cause of nest failure, accounting for 35.7% of all active nests. In general, life history traits of this Mexican Loggerhead Shrike population are like those reported for breeding populations in more northern parts of its range; however, clutch size was smaller and average incubation period was significantly longer, probably because of latitudinally-related environmental factors.

HIGH FREQUENCY OF BATS IN THE DIET OF THE BARN OWL TYTO ALBA IN A LOWLAND DRY FOREST IN TOLIMA, COLOMBIA

Laura María Baldrich — 2024-06-10

The cosmopolitan distribution of the Barn Owl Tyto alba and its relatively well documented diet through the study of pellets have provided evidence of the broad diversity of prey it relies on. In most studies, both in tropical and temperate regions, rodents are its main prey, with other small mammals and vertebrates, and insects complementing its diet. Although bats have been recorded in the diet of T. alba at many localities, they seldom represent an important part of its diet. This study describes the diet of a small colony of T. alba from a mosaic of agricultural fields, pastures for cattle ranching and tropical dry forests in Tolima, central Colombia. Overall, we collected 516 pellets between 2016 and 2017 in a non-systematic manner, and recovered 335 skulls of rodents (67%), bats (29%), birds (3%) and shrews (1%), as well as invertebrate prey. The large proportion of bats in the diet of T. alba in this study is only matched by a few other studies, and further documents the wide range of prey included in the diet of this nocturnal raptor. This is one of the first studies on the diet of T. alba in tropical dry forests in Colombia and complements the existing data on its diet in the American tropics and worldwide.

OFFSPRING SEX RATIO IS RELATED WITH LAYING DATE AND HATCHING SEQUENCE IN THE MAGELLANIC PENGUIN SPHENISCUS MAGELLANICUS

Marcelo Bertellotti — 2024-07-10

We analyzed the variation in the secondary sex ratio of Magellanic Penguin Spheniscus magellanicus breeding in six colonies on the Patagonian coast of Argentina. We tested the effects of laying date and hatching sequence on the probability of producing sons and daughters. The global secondary sex ratio did not differ from equality, and there were no differences among the colonies. However, regardless of the colony, laying date, and hatching sequence, there was a significant effect on the proportion of males and females reared. Pairs that were laid early in the breeding season were more likely to raise a male. In addition, offspring that hatched first were more likely to be male than those that hatched second. Our results are consistent with the adaptive importance of producing males, likely the costliest sex, early in the breeding season or early in the brood when food resources are still abundant.

BIRD COMMUNITIES RESPOND TO THE SEASONAL FRUIT AND FLOWER AVAILABILITY IN A FRAGMENTED TROPICAL ANDEAN LANDSCAPE

Mariana Villegas — 2024-07-11

Fire is one of the main causes of fragmentation in tropical Andean forests. Fragmentation can influence plant reproductive phenology, which in turn affects bird communities. In the Bolivian Yungas, we investigated how the seasonal availability of fruits and flowers affects bird richness, abundance and bird community composition in forest edges and adjacent bracken (Pteridium ferns) dominated areas. We captured birds with mist nets at eight sites during the dry, transition and wet seasons, and recorded fruit and flower availability through phenological observations and plant collections. We examined variation in species richness and abundance using generalized linear mixed-effects models, and bird species composition in each season using multivariate analyses. Fruit availability was higher in the transition and wet seasons, and lowest in the dry season, while flower availability did not differ among seasons. Bird species richness and abundance were significantly higher in bracken areas, although there was significantly lower fruit availability than at the forest edge, and these were mainly generalist bird species that may be tolerant to disturbance. Total bird abundance increased with higher fruit availability in both habitats, and with flower availability at the forest edge. Bird species composition differed between forest edges and bracken areas in the transition and the wet seasons, being influenced by fruiting and flowering phenology in the dry and transition seasons, and elevation in all seasons. Our results show the varying seasonal influence of plant reproductive phenology on avian communities of disturbed habitats, although other large scale factors associated with fragmentation may also shape bird communities.

PREVALENCE OF WHITE SPOTTING IN THE PLUMAGE OF THE FULVOUS WREN CINNYCERTHIA FULVA IN THE BOLIVIAN ANDES

Rhayza Cortes-Romay — 2024-09-12

We assessed the prevalence of white-spotting in the plumage of a Fulvous Wren Cinnycerthia fulva population and present evidence that this phenomenon occurs in other species populations. We captured and observed individuals with varying white facial patches in Cotapata National Park (La Paz, Bolivia). Fifty-two percent of the captured individuals (N=17) showed some degree of white feathering; in all cases, white patches occurred only on the head and fitted the description of ‘white-spotting’, a pattern likely associated with age, physical fitness and status. In avian community surveys, we often observed Fulvous Wrens attending mixed-species flocks, and 36% of all the flocks had at least one individual with facial white-spotting. An examination of photographic records of the species showed that spotting occurs in other populations, with most records from Bolivia showing some degree of facial white-spotting. Our study exemplifies the utility of citizen-science platforms for documenting atypical plumage in wild bird populations.

NECTAR ROBBING BY THE RED-TAILED COMET SAPPHO SPARGANURUS: THE VALUE OF CITIZEN SCIENCE TO DOCUMENT INFREQUENT BEHAVIOR IN BIRDS

Luciana Telleria — 2024-03-17

Nectar robbing by hummingbirds, the extraction of nectar using perforations instead of the corolla, is seldom documented in the literature. Here, we present the first photographic record of nectar robbing by the Red-tailed Comet Sappho sparganurus in Bolivia and examine published and photographic evidence of this behavior. We found no published evidence of nectar robbing by Red-tailed Comets in peer-reviewed literature. However, we found that about 4% of the photographs of hummingbird-flower interactions involving this species on citizen science platforms showed clear nectar robbing behavior. Our results suggest that nectar robbing is not an uncommon behavior for the Red-tailed Comet and highlight the hidden, yet immense, value of citizen science photographic databases to document avian natural history and behavior.

ACTIVE ANTING BEHAVIOR IN RED-CRESTED CARDINAL PAROARIA CORONATA AND RUFOUS-COLLARED SPARROW ZONOTRICHIA CAPENSIS

Mario Luis Chatellenaz — 2024-09-10

Over 200 bird species exhibit a behavior known as anting, wherein birds spread ants or other arthropods, along with their secretions, to their plumage. Anting is hypothesized to serve purposes such as controlling skin bacteria or fungi, repelling ectoparasites, alleviating skin irritation during molting, or pre-treating ants prior to ingestion. In this note, I present the first records of anting behavior in an adult Red-crested Cardinal Paroaria coronata, and in an adult and a juvenile Rufous-collared Sparrow Zonotrichia capensis. These birds rubbed ants of Camponotus mus (Formicidae: Formicinae) on their feathers. The cardinal rubbed the ants on the remiges of both wings, similar to the juvenile sparrow, while the adult sparrow applied them on its fairly deteriorated rectrices. In none of the cases were the ants consumed. These observations suggest that, at least in adult sparrows, the application of ants responded to the presence of ectoparasites.