Birds are able to recognize and learn to avoid attacking unpalatable, chemically defended butterflies after unpleasant experiences with them. It has also been suggested that birds learn to avoid prey that are efficient at escaping. This, however, remains poorly documented. Here, we argue that butterflies may utilize a variety of escape tactics against insectivorous birds and review evidence that birds avoid attacking butterflies that are hard to catch. We suggest that signaling difficulty of capture to predators is a widespread phenomenon in butterflies, and this ability may not be limited to palatable butterflies. The possibility that both palatable and unpalatable species signal difficulty of capture has not been fully explored, but helps explain the existence of aposematic coloration and escape mimicry in butterflies lacking defensive chemicals. This possibility may also change the role that putative Müllerian and Batesian mimics play in a variety of classical mimicry rings, thus opening new perspectives in the evolution of mimicry in butterflies.
1. This article reports the responses of wild, adult jacamars to butterflies with distinct coloration types in central Brazil. Fully aposematic species, i.e. those exhibiting bright and/or contrasting colours on both wing surfaces (= A/A), were predominantly sight‐rejected by birds and, with one exception, the few butterflies attacked and captured were taste‐rejected afterwards.2. Aposematic and cryptic butterflies, i.e. those exhibiting bright and/or contrasting colours on the upper and cryptic colours on the underwings (= A/C) were sight‐rejected while flying, when they show their conspicuous colours to predators. This suggests that birds associate butterfly colours with their difficulty of capture, as in the case of Morpho and several Coliadinae species. These butterflies, however, were heavily attacked at rest, when they are cryptic.3, Fully cryptic butterflies, i.e. those exhibiting cryptic colours on both wing surfaces (= C/C) did not elicit sight rejections by birds. Comparisons involving the number of attacks and the capture success of flying and resting individuals showed no significant differences in species more frequently observed like some cracker butterflies (Hamadryas feronia and H. februa) and Taygetis laches. Compared with the A/C Coliadinae, these butterflies showed a lesser, although not significantly different, ability to escape while flying, but a greater and significantly different ability to escape while at rest.4, A hunting tactic of jacamars, which consists of following flying A/C and C/C butterflies on sight, and waiting until they perch to locate and attack them, is described for the first time.
Although titanium (Ti) is known to elicit a foreign body response when implanted into humans, Ti implant healing resembles normal wound healing in terms of inflammatory cell recruitment and inflammation persistence. Rough implant surfaces may present better conditions for protein adsorption and for the adhesion of platelets and inflammatory cells such as neutrophils. Implanted biomedical devices initially interact with coagulating blood; however, direct contact between the oxide layer of the implant and neutrophils has not been completely described. The aim of the present study is to compare the behaviours of neutrophils in direct contact with different Ti surfaces. Isolated human neutrophils were placed into contact with Ti discs, which had been rendered as 'smooth' or 'rough', following different surface treatments. Scanning electron microscopy and flow cytometry were used to measure cell adhesion to the surfaces and exposure of membrane proteins such as CD62L and CD11b. Topographic roughness was demonstrated as higher for SLA treated surfaces, measured by atomic force microscopy and elemental analysis was performed by energy dispersive X-ray, showing a similar composition for both surfaces. The adhesion of neutrophils to the 'rough' Ti surface was initially stronger than adhesion to the 'smooth' surface. The cell morphology and adhesion marker results revealed clear signs of neutrophil activation by either surface, with different neutrophil morphological characteristics being observed between the two surface types. Understanding the cellular mechanisms regulating cell-implant interactions should help researchers to improve the surface topography of biomedical implant devices.
This study compares the diet of the Galbula ruficauda between sexes, seasons (rainy season and dry season) and two locations relatively close to each other along a gallery forest of the Maranhão River and one of its tributaries in central Brazil. Additional comparisons involving the results obtained in this study with data on the diet of this bird in another site in Central Brazil and a forest site in Costa Rica were also carried out. Insects attacked and consumed by wild birds in central Brazil belong to seven orders including: Hymenoptera, Diptera, Lepidoptera, Odonata, Coleoptera, Orthoptera e Mantodea. Small insects like Diptera and micro-Hymenoptera constituted the most abundant items in the diet of this bird, followed by relatively large Hymenoptera (especially wasps), Lepidoptera, Odonata, Coleoptera, Orthoptera and Mantodea. Comparisons involving the proportion of these items in the birds' diet showed no significant differences between sexes, but showed strong differences between seasons. Comparisons involving different locations in Central Brazil showed significant differences in some cases but not in others. Comparisons involving locations in central Brazil and data obtained in Costa Rica also furnished strong significant differences between them.
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