Francisco Dénes

University of São Paulo | USP · Department of Ecology (IB)

Estimating abundance and population size is essential for many ecological and conservation studies of parrots. Achieving these goals requires methods that yield reliable estimates, but parrot traits can make them difficult to detect, count, and capture. We review established and emergent sampling and analytical methods used to estimate parrot abund...

Despite of the widespread co-occurrence of multiple invaders, little is known on their combined ecological impacts and on their effects on different life stages of native species. We assessed the joint impacts of four non-native mammals (cattle, horse, European hare Lepus europaeus, and wild boar Sus scrofa) on seed surplus and seedling abundance o...

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effect...

Declines in raptor populations often result from the transformation of natural habitats to anthropogenic land uses, but the rate of population change can vary greatly among species. Declines associated with land transformation have been linked to loss of foraging habitat, prey resources and nest sites due to expanding cultivation, overgrazing and d...

Inference and estimates of abundance are critical for quantifying population dynamics and impacts of environmental change. Yet imperfect detection and other phenomena that cause zero inflation can induce estimation error and obscure ecological patterns. Recent statistical advances provide an increasingly diverse array of analytical approaches for e...

To recover species at risk, it is necessary to identify habitat critical to their recovery. Challenges for species with large ranges (thousands of square kilometres) include delineating management unit boundaries within which habitat use differs from other units, along with assessing any differences among units in amounts of and threats to habitat...

To recover species at risk, it is necessary to identify habitat critical to their recovery. Challenges for species with large ranges (thousands of square kilometres) include delineating management unit boundaries within which habitat use differs from other units, along with assessing amounts of and threats to habitat over time. We developed a repro...

Parrots stand out among birds because of their poor conservation status and the lack of available information on their population sizes and trends. Estimating parrot abundance is complicated by the high mobility, gregariousness, patchy distributions, and rarity of many species. Roadside car surveys can be useful to cover large areas and increase th...

BACKGROUND Invasive Africanized honey bees potentially compete with cavity‐nesting birds in South America. However, the impacts of this competition and its conservation consequences to threatened species are poorly known. We quantified the presence of these bees and assessed their competition for cliff cavities used by nesting Lear's macaws Anodorh...

Invasive Africanized honey bees potentially compete with cavity‐nesting birds in South America. However, the impacts caused by this competition and its conservation consequences to threatened species are poorly known. We quantified the presence of these bees and assessed its competition for cliff cavities used by nesting Lear's macaws Anodorhynchus...

Recent research on boreal birds has focused on understanding effects of human activity on populations and their habitats. As bird populations continue to decline, research is often intended to inform conservation and management policies and practices. Research produced under the typical "loading dock" model by Western-trained researchers often fail...

Estimating the population abundance of landbirds is a challenging task complicated by the amount, type, and quality of available data. Avian conservationists have relied on population estimates from Partners in Flight (PIF), which primarily uses roadside data from the North American Breeding Bird Survey (BBS). However, the BBS was not designed to e...

Estimating distribution and abundance of species depends on the probability at which individuals are detected. Butterflies are of conservation interest worldwide, but data collected with Pollard walks - the standard for national monitoring schemes - are often analyzed assuming that changes in detectability are negligible within recommended sampling...

The extinction of ecological functions is increasingly considered a major component of biodiversity loss, given its pervasive effects on ecosystems, and it may precede the disappearance of the species engaged. Dispersal of many large-fruited (>4 cm diameter) plants is thought to have been handicapped after the extinction of megafauna in the Late Pl...

Anecdotic citations of food wasting have been described for parrots, but we lack a comprehensive knowledge about the extent of this behaviour, and its ecological and evolutionary implications. Here, we combine experimental and observational approaches to evaluate the spatial, temporal, typological and taxonomic extent of food wasting by parrots, to...

Aim Most large‐scale species distribution models assume spatially constant habitat selection throughout a species' geographic range. However, there is evidence this assumption may not be valid for a number of boreal bird species, which could lead to biased predictions of density and distribution in range‐wide models. Our goal was to test for and qu...

While Psittaciformes (parrots and allies) are well-recognized as highly-mobile seed predators, their role as seed dispersers has been overlooked until very recently. It remains to be determined whether this role is anecdotic or is a key mutualism for some plant species. We recently found that the large nut-like seeds of the two South American Arauc...

Knowledge about the population size and trends of common bird species is crucial for setting conservation priorities and management actions. Multi-species large-scale monitoring schemes have often provided such estimates relying on extrapolation of relative abundances in particular habitats to large-scale areas. Here we show an alternative to infer...

Counts of territorial (singing) male Eurasian reed warblers (A. scirpaceus) and Great reed warblers (A. arundinaceus). Censused localities and their UTM coordinates (initial and final coordinates for lotic water stretches, and a central coordinate for localities corresponding to lentic water) are provided according to ED 50 datum. The type of marsh...

Seed dispersal is one of the most studied plant–animal mutualisms. It has been proposed that the dispersal of many large-seeded plants from Neotropical forests was primarily conducted by extinct megafauna, and currently by livestock. Parrots can transport large fruits using their beaks, but have been overlooked as seed dispersers. We demonstrate th...

Parrots are largely considered plant antagonists as they usually destroy the seeds they feed on. However, there is evidence that parrots may also act as seed dispersers. We evaluated the dual role of parrots as predators and dispersers of the Critically Endangered Parana pine (Araucaria angustifolia). Eight of nine parrot species predated seeds fro...

Mutually enhancing organisms can become reciprocal determinants of their distribution , abundance, and demography and thus influence ecosystem structure and dynamics. In addition to the prevailing view of parrots (Psittaciformes) as plant antagonists, we assessed whether they can act as plant mutualists in the dry tropical forest of the Bolivian in...

The White-collared Kite (Leptodon forbesi Swann, 1922), previously known by the holotype and three specimens from northeastern Brazil from the late 1980s, is considered by many as a juvenile variant of the Grey-headed Kite (L. cayanensis Latham, 1790). We present new morphological evidence from museum specimens of both species, including a previous...

PalavRas-chave: Procellariiformes, Diomedea exulans, Diomedea dabbenena, albatroz‑errante, albatroz‑de‑tristão, Brasil, taxonomia, conservação. abstRact: Recently, the genus Diomedea has undergone several taxonomic changes, resulting in the split of D. exulans (lato sensu) and D. epomophora (lato sensu) into six different species. Of these, D. exul...

The currently accepted albatross taxonomy, based on characters of external morphology, plumage patterns, tail shape, bill size and coloration, organization of the plates of the bill, and, more recently, molecular data such as cytochrome-b gene sequences, resulted in a division of the family Diomedeidae into four genera: Diomedea, comprising the gre...