Broadening Our Approaches to Studying Dispersal in Raptors

Dispersal is a behavioral process having consequences for individual fitness and population dynamics. Recent advances in technology have spawned new theoretical examinations and empirical studies of the dispersal process in birds, providing opportunities for examining how this information may be applied to studies of the dispersal process in raptors. Many raptors are the focus of conservation efforts; thus, reliable data on all aspects of a species\u27 population dynamics, including dispersal distances, movement rates, and mortality rates of dispersers, are required for population viability analyses that are increasingly used to inform management. Here, we address emerging issues and novel approaches used in the study of avian dispersal, and provide suggestions to consider when developing and implementing studies of dispersal in raptors. Clarifying study objectives is essential for selection of an appropriate methodology and sample size needed to obtain accurate estimates of movement distances and rates. Identifying an appropriate study-area size will allow investigators to avoid underestimating population connectivity and important population parameters. Because nomadic individuals of some species use temporary settling areas or home ranges before breeding, identification of these areas is critical for conservation efforts focusing on habitats other than breeding sites. Study designs for investigating raptor dispersal also should include analysis of environmental and social factors influencing dispersal, to improve our understanding of condition-dependent dispersal strategies. Finally, we propose a terminology for use in describing the variety of movements associated with dispersal behavior in raptors, and we suggest this terminology could be used consistently to facilitate comparisons among studies

Broadening Our Approaches to Studying Dispersal in Raptors

Dispersal is a behavioral process having consequences for individual fitness and population dynamics. Recent advances in technology have spawned new theoretical examinations and empirical studies of the dispersal process in birds, providing opportunities for examining how this information may be applied to studies of the dispersal process in raptors. Many raptors are the focus of conservation efforts; thus, reliable data on all aspects of a species\u27 population dynamics, including dispersal distances, movement rates, and mortality rates of dispersers, are required for population viability analyses that are increasingly used to inform management. Here, we address emerging issues and novel approaches used in the study of avian dispersal, and provide suggestions to consider when developing and implementing studies of dispersal in raptors. Clarifying study objectives is essential for selection of an appropriate methodology and sample size needed to obtain accurate estimates of movement distances and rates. Identifying an appropriate study-area size will allow investigators to avoid underestimating population connectivity and important population parameters. Because nomadic individuals of some species use temporary settling areas or home ranges before breeding, identification of these areas is critical for conservation efforts focusing on habitats other than breeding sites. Study designs for investigating raptor dispersal also should include analysis of environmental and social factors influencing dispersal, to improve our understanding of condition-dependent dispersal strategies. Finally, we propose a terminology for use in describing the variety of movements associated with dispersal behavior in raptors, and we suggest this terminology could be used consistently to facilitate comparisons among studies

Risk evaluations and condom use decisions of homeless youth: a multi-level qualitative investigation.

BackgroundHomeless youth are at higher risk for sexually transmitted infections and unwanted pregnancy than non-homeless youth. However, little is known about how they evaluate risk within the context of their sexual relationships. It is important to understand homeless youths' condom use decisions in light of their sexual relationships because condom use decisions are influenced by relationship dynamics in addition to individual attitudes and event circumstances. It is also important to understand how relationship level factors, sexual event circumstances, and individual characteristics compare and intersect.MethodsTo explore these issues, we conducted semi-structured interviews with 37 homeless youth in Los Angeles County in 2011 concerning their recent sexual relationships and analyzed the data using systematic methods of team-based qualitative data analysis.ResultsWe identified themes of risk-related evaluations and decisions at the relationship/partner, event, and individual level. We also identified three different risk profiles that emerged from analyzing how different levels of risk intersected across individual respondents. The three profiles included 1) Risk Takers, who consistently engage in risk and have low concern about consequences of risk behavior, 2) Risk Avoiders, who consistently show high concern about protection and consistently avoid risk, and 3) Risk Reactors, those who are inconsistent in their concerns about risk and protection and mainly take risks in reaction to relationship and event circumstances.ConclusionsInterventions targeting homeless youth should reflect multiple levels of risk behavior and evaluation in order to address the diversity of risk profiles. Relationship/partner-, event-, and individual-level factors are all important but have different levels of importance for different homeless youth. Interventions should be tailored to address the most important factor contributing to homeless youth reproductive needs

Potential factors influencing nest defense in diurnal North American raptors

Nesting habitat, predator type, and level of reproductive effort influence nest defense behaviors in many bird species, yet no study has examined these or other possible factors influencing nest defense in a cross-species comparison for raptors. Using data from the literature, we grouped the nest defense behaviors of 19 diurnal North American raptors into four categories based on a gradient of aggressiveness. For each species, we identified the cover types where nesting occurred, accessibility of nest location, assessed two indices of reproductive effort, and examined associations between these factors and nest-defense behavior. We also we examined responses by raptor species to different predator types including diurnal avian, nocturnal avian, mammalian (not human), and human. Most raptor species with high reproductive effort exhibited very aggressive nest defense. Most raptor species nesting in open cover types and species with accessible nests showed aggressive nest defense. While many raptors react aggressively toward diurnal and nocturnal avian predators, they exhibit less aggressive defense against potential human predators. Results from this study suggest that a variety of factors may influence nest-defense strategies used by diurnal raptors. However, more work is needed on the relative influence of these factors (including predation risk) and variation in raptor nest defense strategies before general patterns can be elucidated

Use of CT scanning and radiography as legal expert evidence in Paleontology (Trilobites of Morocco)

Altres ajuts: Associació d'Experts Jurídics de Catalunya dins del projecte APTC2019-PALEOThis study presents CT Scanning and radiography techniques applied to invertebrate paleontology, specifically to the detection of trilobites forgeries in Morocco. A well-known technique uses ultraviolet rays to detect falsified resin elements in trilobites. This technique is very effective for the trilobites of the Ordovician of Russia, although it is also used in specimens from other regions as we can see in figure 1: a topotype of the Upper Ordovician of Morocco, Uralichas hispanicus tardus Vela & Corbacho, 2009. This technique is not entirely reliable since it only detects the resin but not the density difference of different broken pieces that can be present in an authentic trilobite and its matrix, so these parts could belong to different specimens. This problem is solved with the utilization of a CT Scanning and in some cases with simple radiography. This paper presents mainly holotypes, paratypes and other specimens included in scientific articles, belonging to the Lower Ordovician, Upper Ordovician and Middle Devonian. The authenticity of the figured specimens are further substantiated and demonstrate that they retain the necessary characters to make an accurate description of the designated new species

Molluscan carbonate geochemistry and paleoceanography of the Late Cretaceous western interior seaway of North America

North Amerlc8 W8S inundated by fJ major eplcontlnental sea during ihe C:retaceo.us Period. The sOljihw6rd transgression of th.e northern Boreal See along the ~\festern Interior Seaway resulted in a meetlng with the northward edv6nclng waters from the GUlf of Mexico (Obradovich and Cobban, 1975). Th1s link was 1n eXlstence by late Albien time and 6llowed for the comm1ngl1ng of the prol1ferous Arctic and Gulf rnar1ne faunas (F1g. 1). By early Campanlan time, there was a widening of B6ffln Bay wlth a slrnult8neous subsidence 1n the Arct1c Archlpelago and Sverdrup 6as1n (W11liam and Stelck, 1975). Williams and Burk (1964) found 6 break 1n the marines sedlmentatlon in the f1anltoba area, suggesting Bland corlnectlon from the Dlstrlct of Keewatln through eastern M6fl1toba to the lake Sl~perlor reglon, lmplying that the only dlrect connection between the Interlor Sea with Baffln Bay, was yia the Arct1c. This hiatus was also documented by Meek and Hayden (1861) ln the United states between the Niobrara and Pierre Format1ons. Jeletzky (1971) suggested that the retreat of the sea towards the east was by a serles of strong pulses resultlng in the regression of the Campanlan and M66str1chtlan seas. During ttle Cretaceous1 the r1s1ng Corl1111era caused the western shoreline of the Interlor Sea to migrate eastwards and the Cordillera'l detritus produced deltaic cornplexes from the Mackenzie Valley to Ne\N Mexlcoo The foreland basin was continually subslding and thls down\",arplng aided in the eastward m1gration of the western shorel1ne. Thls also lndicates that trle water 'tIes becom1ng deeper in the central Plains sect10n of the Seaway (Fig. 2)

Evolution of Communal Roosting: A Social Refuge-Territory Prospecting Hypothesis

© 2018 The Raptor Research Foundation, Inc. Avian communal roosts provide insight into evolution and serve as focal points for conservation. Nonbreeding Crested Caracaras (Caracara cheriway; hereafter caracaras) use communal roosts, but evolutionary implications have not been explored. Though nonbreeding caracaras are nonmigratory, the scientific literature fails to explain seasonal differences in their movement and survival concurrent with seasonal consistency in their habitat and social ecology. In the Social Refuge-Territory Prospecting hypothesis we propose, socially subordinate nonbreeding caracaras precluded from breeding by habitat limitation use communal roosts as social refuges to avoid aggression from dominant territory holders during nonbreeding seasons, and engage in territory prospecting during breeding seasons. Communal roosts thus become central places from which to forage not for food, but for a breeding territory. Because foraging gains are stored as remembered information, competition costs resulting from public information are preempted. For the Social Refuge-Territory Prospecting hypothesis to be valid, two criteria need to be met. First, communal roost use needs to be higher during nonbreeding seasons. Second, a measure of fitness needs to be used to evaluate the hypothesis as an evolutionarily stable strategy. To meet these criteria, in this study we report that numbers of nonbreeding caracaras using a communal roost in Florida are higher during nonbreeding seasons (mean = 111.8 individuals/night) than during breeding seasons (mean = 60.7 individuals/night) as counted from August 2006-April 2009 (n = 407 counts). We also compare differential survival by season from previous work to demonstrate that by limiting exploratory movements to times when prospecting is most informative, nonbreeding caracaras balance maximizing survival against the likelihood of securing a breeding territory. Our hypothesis provides a unifying explanation for otherwise unexplained paradoxes in the ecology of nonbreeding caracaras, and may be useful in guiding conservation and expanding our understanding of the ecology of other communally roosting birds

Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins

Background: The deep-sea hypersaline anoxic basins (DHABs) of the Mediterranean (water depth similar to 3500 m) are some of the most extreme oceanic habitats known. Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB haloclines and brines, loriciferans are the only metazoan reported to inhabit the anoxic DHAB brines. Our goal was to further investigate metazoan communities in DHAB haloclines and brines. Results: We report observations from sediments of three DHAB (Urania, Discovery, L'Atalante) haloclines, comparing these to observations from sediments underlying normoxic waters of typical Mediterranean salinity. Due to technical difficulties, sampling of the brines was not possible. Morphotype analysis indicates nematodes are the most abundant taxon; crustaceans, loriciferans and bryozoans were also noted. Among nematodes, Daptonema was the most abundant genus; three morphotypes were noted with a degree of endemicity. The majority of rRNA sequences were from planktonic taxa, suggesting that at least some individual metazoans were preserved and inactive. Nematode abundance data, in some cases determined from direct counts of sediments incubated in situ with CellTracker (TM) Green, was patchy but generally indicates the highest abundances in either normoxic control samples or in upper halocline samples; nematodes were absent or very rare in lower halocline samples. Ultrastructural analysis indicates the nematodes in L'Atalante normoxic control sediments were fit, while specimens from L'Atalante upper halocline were healthy or had only recently died and those from the lower halocline had no identifiable organelles. Loriciferans, which were only rarely encountered, were found in both normoxic control samples as well as in Discovery and L'Atalante haloclines. It is not clear how a metazoan taxon could remain viable under this wide range of conditions. Conclusions: We document a community of living nematodes in normoxic, normal saline deep-sea Mediterranean sediments and in the upper halocline portions of the DHABs. Occurrences of nematodes in mid-halocline and lower halocline samples did not provide compelling evidence of a living community in those zones. The possibility of a viable metazoan community in brines of DHABs is not supported by our data at this time

Environmental Correlates of Nesting Success in Red-Shouldered Hawks

We evaluated the influence of weather on reproduction of the Red-shouldered Hawk (Buteo lineatus) in an agricultural landscape in south-central Florida where we found relatively high densities of successfully nesting hawks. We used a generalized linear modeling approach within an information-theoretic framework to examine the influence of total rainfall, rainfall frequency, and temperature on the timing of nesting, nesting success, and productivity of hawks during 1995-2000. The best models indicated an influence of rainfall frequency and laying period on hawk reproduction. During years with less frequent rainfall in the summer and fall months prior to the beginning of the breeding season, fewer pairs attempted to nest, and hawks nested later and had smaller clutch sizes and lower productivity. Hawks that nested later in the breeding season had lower hatching success and lower overall nest success. Although Red-shouldered Hawks are generally reported to inhabit forested landscapes throughout their range, a common feature seems to be a dependence on wetlands and riparian habitat for foraging. We propose that the proportion of wetlands throughout the landscape is a unique aspect of south-central Florida that may allow for persistence of unusually high numbers of hawks