Long‐distance movements and evidence of post‐breeding elevational movements by Cassin’s Vireos

Bird migration is often framed as a straightforward journey between one breeding site and one wintering site, but recent research has shown that the reality is often more complex. Many species of birds undertake short‐distance movements separate from long‐distance migration. Such movements appear to be common in species that breed in western North America, where mountainous terrain creates a mosaic of habitats and climatic conditions. However, individual‐based tracking studies have disproportionately focused elsewhere, leaving gaps in our understanding of the year‐round movements of western species. I used tracking data from light‐level geolocators and citizen science data from eBird to study the movements of Cassin’s Vireos (Vireo cassinii) breeding in the Sierra Nevada mountains of California, USA. During three breeding seasons (2013–2015), my observations suggested that Cassin’s Vireos vacate their breeding territories during the post‐breeding period in July and August. In April and May 2016, I tagged 22 Cassin’s Vireos with light‐level geolocators and, in April and May 2017, recaptured four that had retained their geolocators. Geolocator data showed that these four birds remained in the same geographic region as their breeding territories (likely the same mountain range) during the post‐breeding period in July and August 2016, ruling out the possibility of long‐distance movements during this time. Analysis of eBird citizen science data suggested that Cassin’s Vireos undertake short‐distance molt‐migration to higher elevations in the Sierra Nevada Mountains during the post‐breeding period. Geolocator data revealed that long‐distance fall migration took place in September and spring migration in April or May, and the four birds spent the winter in different parts of the Mexican winter range of Cassin’s Vireos. These results add to the body of literature on the complex movements of migratory songbirds breeding in the mountains of western North America, an understanding that will be important for effective conservation in the future.     

Serotonin modulates locomotory behavior and coordinates egg‐laying and movement in Caenorhabditis elegans

Biogenic amines have been implicated in the modulation of neural circuits involved in diverse behaviors in a wide variety of organisms. In the nematode C. elegans, serotonin has been shown to modulate the temporal pattern of egg‐laying behavior. Here we show that serotonergic neurotransmission is also required for modulation of the timing of behavioral events associated with locomotion and for coordinating locomotive behavior with egg‐laying. Using an automated tracking system to record locomotory behavior over long time periods, we determined that both the direction and velocity of movement fluctuate in a stochastic pattern in wild‐type worms. During periods of active egg‐laying, the patterns of reversals and velocity were altered: velocity increased transiently before egg‐laying events, while reversals increased in frequency following egg‐laying events. The temporal coordination between egg‐laying and locomotion was dependent on the serotonergic HSN egg‐laying motorneurons as well as the decision‐making AVF interneurons, which receive synaptic input from the HSNs. Serotonin‐deficient mutants also failed to coordinate egg‐laying and locomotion and exhibited an abnormally low overall reversal frequency. Thus, serotonin appears to function specifically to facilitate increased locomotion during periods of active egg‐laying, and to function generally to modulate decision‐making neurons that promote forward movement. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 303–313, 2001     

SEB‐3, a CRF receptor‐like GPCR,regulates locomotor activity states,stress responses and ethanol tolerance in Caenorhabditis elegans

The CRF (corticotropin‐releasing factor) system is a key mediator of the stress response. Alterations in CRF signaling have been implicated in drug craving and ethanol consumption. The development of negative reinforcement via activation of brain stress systems has been proposed as a mechanism that contributes to alcohol dependence. Here, we isolated a gain‐of‐function allele of seb‐3, a CRF receptor‐like GPCR in Caenorhabditis elegans, providing an in vivo model of a constitutively activated stress system. We also characterized a loss‐of‐function allele of seb‐3 and showed that SEB‐3 positively regulates a stress response that leads to an enhanced active state of locomotion, behavioral arousal and tremor. SEB‐3 also contributed to acute tolerance to ethanol and to the development of tremor during ethanol withdrawal. Furthermore, we found that a specific CRF₁ receptor antagonist reduced acute functional tolerance to ethanol in mice. These findings demonstrate functional conservation of the CRF system in responses to stress and ethanol in vertebrates and invertebrates.     

Species‐specific habitat preferences do not shape the structure of a crested newt hybrid zone (Triturus cristatus x T. carnifex)

Reproductive isolation barriers maintain the integrity of species by preventing interspecific gene flow. They involve temporal, habitat or behavioral isolation acting before fertilization, and postzygotic isolation manifested as hybrid mortality or sterility. One of the approaches of how to study reproductive isolation barriers is through the analysis of hybrid zones. In this paper, we describe the structure of a hybrid zone between two crested newt species (Triturus cristatus and T. carnifex) in the southern part of the Czech Republic using morphological, microsatellite, and mitochondrial (mtDNA) markers. Specifically, we tested the hypothesis that the structure of the hybrid zone is maintained by species‐specific habitat preferences. Comparing the genetic structure of populations with geographical and ecological parameters, we found that the hybrid zone was structured primarily geographically, with T. cristatus‐like populations occurring in the northeast and T. carnifex‐like populations in the southwest. Despite T. cristatus tending to occur in deeper ponds and T. carnifex on localities with more shading, the effect of both ecological parameters on the structure of the zone was minimal. Next, we corroborated that T. carnifex individuals and some hybrids possess mtDNA of T. dobrogicus, whose nuclear background was not detected in the studied hybrid zone. Hybridization between T. carnifex and T. dobrogicus (resulting in unidirectional mtDNA introgression) had to predate subsequent formation of the hybrid zone between T. cristatus and T. carnifex. Populations of crested newts in the southern part of the Czech Republic thus represent a genetic mosaic of nuclear and mitochondrial genomes of three species.     

Male and female rufous‐and‐white wrens do not match song types with same‐sex rivals during simulated territorial intrusions

In birds with song repertoires, song‐type matching occurs when an individual responds to another individual's song by producing the same song type. Song‐type matching has been described in multiple bird species and a growing body of evidence suggests that song‐type matching may serve as a conventional signal of aggression, particularly in male birds in the temperate zone. Few studies have investigated song‐type matching in tropical birds or female birds, in spite of the fact that avian biodiversity is highest in the tropics, that female song is widespread in the tropics, and that female song is the ancestral state among songbirds. In this study of rufous‐and‐white wrens Thryophilus rufalbus, a resident neotropical songbird where both sexes sing, we presented territorial males and females with playback that simulated a territorial rival producing shared and unshared songs. In response, both males and females sang matched song types at levels statistically equal to levels expected by chance. Furthermore, males and females exhibited similar levels of aggression and similar vocal behaviours in response to playback of both shared and unshared songs. These results indicate that rufous‐and‐white wrens do not use song‐type matching in territorial conflicts as a conventional signal of aggression. We discuss alternative hypotheses for the function of song‐type sharing in tropical birds. In particular, we point out that shared songs may play an important role in intra‐pair communication, especially for birds where males and females combine their songs in vocal duets, and this may supersede the function of song‐type matching in some tropical birds.     

Sexual dimorphism,phenotypic integration,and the evolution of head structure in casque‐headed lizards

Sexes can differ in features associated with differential reproduction, which can be used during courtship or aggressive encounters. Some traits tend to evolve independently between sexes and emerge as sexually dimorphic within the organismal phenotype. We characterize such a relationship by estimating the phenotypic integration of the head morphology and modularity of the crest in the casque‐headed lizards (Corytophanidae). In this clade, some species show extreme sexual dimorphism (e.g., head crests in the genus Basiliscus) while in others, both sexes are monomorphic. To characterize these patterns, we define phenotypic integration at the interspecific level as a pattern or network of traits evidenced by phylogenetically adjusted correlations that persist among species. At this level, modularity is an increased connectedness (e.g., higher correlation) among sections of these networks that persist in a lineage during the evolution of complex phenotypes. To test both concepts, we used phylogenetic geomorphometrics to characterize the head structure of corytophanid lizards, based on a time‐calibrated phylogeny that includes candidate fossil ancestors. We found evidence of an older diversification of corytophanids than previously reported (~67 vs. ~23.5 MYA) and show that this clade includes two morphological head architectures: (1) Sexually dimorphic crests present in males that are evolving independently from the rest of the head structure, and (2) full integration of the head morphology in monomorphic species. We propose that both architectures are optimal evolutionary trajectories of the parietal crest bones in the head of these lizards. In sexually dimorphic species, these bones are elongated and thinner, and gave rise to the extended crest used in male courtship displays. In monomorphic species, the parietal crest grew thicker in both sexes to allow for a better insertion of muscles associated with a stronger bite.     

Long‐term effectiveness of oral second‐generation antipsychotics in patients with schizophrenia and related disorders: a systematic review and meta‐analysis of direct head‐to‐head comparisons

Second‐generation antipsychotics (SGAs) are recommended for maintenance treatment in schizophrenia. However, comparative long‐term effectiveness among SGAs is unclear. Here we provide a systematic review and meta‐analysis of randomized trials lasting ≥?6 months comparing SGAs head‐to‐head in schizophrenia and related disorders. The primary outcome was all‐cause discontinuation. Secondary outcomes included efficacy and tolerability, i.e., psychopathology, inefficacy‐related and intolerability‐related discontinuation, relapse, hospitalization, remission, functioning, quality of life, and adverse events. Pooled risk ratio and standardized mean difference were calculated using random‐effects models. Across 59 studies (N=45,787), lasting 47.4±32.1 weeks (range 24‐186), no consistent superiority of any SGA emerged across efficacy and tolerability outcomes. Regarding all‐cause discontinuation, clozapine, olanzapine and risperidone were significantly (p<0.05) superior to several other SGAs, while quetiapine was inferior to several other SGAs. As to psychopathology, clozapine and olanzapine were superior to several other SGAs, while quetiapine and ziprasidone were inferior to several other SGAs. Data for other efficacy outcomes were sparse. Regarding intolerability‐related discontinuation, risperidone was superior and clozapine was inferior to several other SGAs. Concerning weight gain, olanzapine was worse than all other compared non‐clozapine SGAs, and risperidone was significantly worse than several other SGAs. As to prolactin increase, risperidone and amisulpride were significantly worse than several other SGAs. Regarding parkinsonism, olanzapine was superior to risperidone, without significant differences pertaining to akathisia. Concerning sedation and somnolence, clozapine and quetiapine were significantly worse than some other SGAs. In summary, different long‐term SGA efficacy and tolerability patterns emerged. The long‐term risk‐benefit profiles of specific SGAs need to be tailored to individual patients to optimize maintenance treatment outcomes.     

American marten and fisher do not segregate in space and time during winter in a mixed‐forest system

Understanding the mechanisms of coexistence between ecologically similar species is an important issue in ecology. Carnivore coexistence may be facilitated by spatial segregation, temporal avoidance, and differential habitat selection. American martens Martes americana and fishers Pekania pennanti are medium‐sized mustelids that occur sympatrically across portions of North America, yet mechanisms of coexistence between the two species are not fully understood. We assessed spatial and temporal partitioning in martens and fishers in the Upper Peninsula of Michigan, USA, using camera trap data collected during winter 2013–2015. To investigate spatial segregation, we used a dynamic occupancy model to estimate species’ occupancy probabilities and probabilities of persistence and colonization as a function of covariates and yearly occupancy probability for the other species. Temporal segregation was assessed by estimating diel activity overlap between species. We found weak evidence of spatial or temporal niche partitioning of martens and fishers. There was high overlap in forest cover selection, and both marten and fisher occupancy were positively correlated with deciduous forests (excluding aspen [Populus tremuloides]). There was strong temporal overlap (; CI = 0.79–0.82) with both species exhibiting largely crepuscular activity patterns. Co‐occurrence of martens and fishers appears to be facilitated by mechanisms not investigated in this study, such as partitioning of snow features or diet. Our results add additional insights into resource partitioning of mesocarnivores, but further research is required to enhance our understanding of mechanisms that facilitate marten and fisher coexistence.     

To pace or not to pace: a pilot study of four‐ and five‐gaited Icelandic horses homozygous for the DMRT3 ‘Gait Keeper’ mutation

The Icelandic horse is a breed known mainly for its ability to perform the ambling four‐beat gait ‘tölt’ and the lateral two‐beat gait pace. The natural ability of the breed to perform these alternative gaits is highly desired by breeders. Therefore, the discovery that a nonsense mutation (C>A) in the DMRT3 gene was the main genetic factor for horses' ability to perform gaits in addition to walk, trot and canter was of great interest. Although several studies have demonstrated that homozygosity for the DMRT3 mutation is important for the ability to pace, only about 70% of the homozygous mutant (AA) Icelandic horses are reported to pace. The aim of the study was to genetically compare four‐ and five‐gaited (i.e. horses with and without the ability to pace) AA Icelandic horses by performing a genome‐wide association (GWA) analysis. All horses (n = 55) were genotyped on the 670K Axiom Equine Genotyping Array, and a GWA analysis was performed using the genabel package in r . No SNP demonstrated genome‐wide significance, implying that the ability to pace goes beyond the presence of a single gene variant. Despite its limitations, the current study provides additional information regarding the genetic complexity of pacing ability in horses. However, to fully understand the genetic differences between four‐ and five‐gaited AA horses, additional studies with larger sample materials and consistent phenotyping are needed.     

Laterality in semi‐free‐ranging black and white ruffed lemurs (Varecia variegata variegata): head‐tilt correlates with hand use during feeding

Previous studies in human and chimpanzee infants have identified a predictive relationship between early rightward head orientation and later right hand use. Data from lemurs suggest a leftward bias in hand preference, but there are no data on head positioning. The purpose of this study was to examine the relationship between head and hand preferences in the black and white ruffed lemur (Varecia variegata variegata). Ruffed lemurs rotate the head vertically during chewing in a behavior called head‐tilting. Frequency of head‐tilting and bouts of unimanual hand use were measured during normal feeding in a semi‐free‐ranging population of lemurs. Subjects were provisioned at feeding platforms twice daily with fresh fruits, vegetables, and other food items. Sampling was spontaneous and all observations were videotaped. No group‐level bias was found for head‐tilting, but a left hand bias emerged for hand use. A positive relationship was found between direction of head‐tilting preference and direction of hand use preference such that left head‐tilts increased as left hand use increased. Furthermore, left head‐tilts increased as the degree of hand preference lateralization increased. When the hand used to bring food to the mouth just before head‐tilting was examined, there was a strong bias for the left hand to precede left head‐tilts. For right head‐tilts, however, lemurs were equally likely to use either hand before head‐tilting. Overall a strong relationship was found between the left hand and left head‐tilting in black and white ruffed lemurs, suggesting a common link between these behaviors. However, the direction of bias was different from that seen in human and chimpanzee studies. Additional studies on patterns of laterality would be informative for understanding how laterality has changed across the primate order and the adaptive significance of laterality in primates. Am. J. Primatol. 71:1032–1040, 2009. © 2009 Wiley‐Liss, Inc.     

Food deprivation and nicotine correct akinesia and freezing in Na+‐leak current channel (NALCN)‐deficient strains of Caenorhabditis elegans

Mutations in various genes adversely affect locomotion in model organisms, and thus provide valuable clues about the complex processes that control movement. In Caenorhabditis elegans, loss‐of‐function mutations in the Na⁺ leak current channel (NALCN) and associated proteins (UNC‐79 and UNC‐80) cause akinesia and fainting (abrupt freezing of movement during escape from touch). It is not known how defects in the NALCN induce these phenotypes or if they are chronic and irreversible. Here, we report that akinesia and freezing are state‐dependent and reversible in NALCN‐deficient mutants (nca‐1;nca‐2, unc‐79 and unc‐80) when additional cation channels substitute for this protein. Two main measures of locomotion were evaluated: spontaneous movement (traversal of >2 head lengths during a 5 second observation period) and the touch‐freeze response (movement greater than three body bends in response to tail touch). Food deprivation for as little as 3 min stimulated spontaneous movement and corrected the touch‐freeze response. Conversely, food‐deprived animals that moved normally in the absence of bacteria rapidly reverted to uncoordinated movement when re‐exposed to food. The effects of food deprivation were mimicked by nicotine, which suggested that acetylcholine mediated the response. Nicotine appeared to act on interneurons or motor neurons rather than directly at the neuromuscular junction because levamisole, which stimulates muscle contraction, did not correct movement. Neural circuits have been proposed to account for the effects of food deprivation and nicotine on spontaneous movement and freezing. The NALCN may play an unrecognized role in human movement disorders characterized by akinesia and freezing gait.     

A new method for catching cavity‐nesting birds during egg laying and incubation

ABSTRACT The physiological condition of female birds during the egg‐laying and incubation periods is of considerable interest and yet is relatively understudied in wild birds, primarily due to the difficulty of catching birds during this period without causing nest desertion. We therefore developed a box‐net to capture cavity‐nesting birds using sections of a mist‐net placed around a metal cubic frame. We captured female Great Tits (Parus major) as they left nest boxes during the egg‐laying and incubation periods and measured desertion rates. Using box‐nets, we captured 108 of 119 (90%) females during egg laying and 10 of 12 (83%) during incubation. Our recapture rate over two consecutive days during incubation was 50% (5 of 10). Females not captured left nest boxes before we attempted to capture them, escaped through a hole in the mist‐net, or remained in nest boxes for more than 2 h, after which we ended capture attempts. Overall, 22% of egg‐laying females deserted, with desertion rates highest early in the egg‐laying period. Desertion rates of females captured using box‐nets did not differ from those of undisturbed females. One of 10 females captured in a box‐net deserted during the incubation period. Box‐nets are portable, can be set up and taken down quickly and easily, and could potentially be used with nest boxes or natural cavities at any height. Box‐nets are easy to construct and adaptable for use with an array of cavity‐nesting birds, and can be an important tool for studying female physiology during egg laying and incubation.     

Pelvic function in anuran jumping: Interspecific differences in the kinematics and motor control of the iliosacral articulation during take‐off and landing

Although the anuran pelvis is thought to be adapted for jumping, the function of the iliosacral joint has seen little direct study. Previous work has contrasted the basal “ lateral‐bender ” pelvis from the “ rod‐like ” pelvis of crown taxa hypothesized to function as a sagittal hinge to align the trunk with take‐off forces. We compared iliosacral movements and pelvic motor patterns during jumping in the two pelvic types. Pelvic muscle activity patterns, iliosacral anteroposterior (AP) movements and sagittal bending of the pelvis during the take‐off and landing phases were quantified in lateral bender taxa Ascaphus (Leiopelmatidae) and Rhinella (Bufonidae) and the rod‐like Lithobates (Ranidae). All three species exhibit sagittal extension during take‐off, therefore, both pelvic types employ a sagittal hinge. However, trunk elevation occurs significantly earlier in the anuran rod‐like pelvis. Motor patterns confirm that the piriformis muscles depress the urostyle while the longissimus dorsi muscles elevate the trunk during take‐off. However, the coccygeoiliacus muscles also produce anterior translation of the sacrum on the ilia. A new model illustrates how AP translation facilitates trunk extension in the lateral‐bender anurans that have long been thought to have limited sagittal bending. During landing, AP translation patterns are similar because impact forces slide the sacrum from its posterior to anterior limits. Sagittal flexion during landing differs among the three taxa depending on the way the species land. AP translation during landing may dampen impact forces especially in Rhinella in which pelvic function is tuned to forelimb‐landing dynamics. The flexibility of the lateral‐bender pelvis to function in sagittal bending and AP translation helps to explain the retention of this basal configuration in many anurans. The novel function of the rod‐like pelvis may be to increase the rate of trunk elevation relative to faster rates of energy release from the hindlimbs enabling them to jump farther. J. Morphol. 277:1539–1558, 2016. © 2016 Wiley Periodicals, Inc.     

Home‐ranges,population densities,vocal behavior,and post‐fledging movements of Cipo Canasteros (Asthenes luizae,Furnariidae), a rock‐specialist endemic of the highlands of eastern Brazil

Cipo Canasteros (Asthenes luizae, Furnariidae) have a fragmented and limited range restricted to the campos rupestres (rupestrian grasslands) habitat in the Brazilian highlands of the Espinhaço Range, and little is known about their behavior, ecology, and population biology. From March 2009 to November 2010, we monitored birds (24 banded and 22 radio‐tracked) at two study sites at Serra do Cipó in the state of Minas Gerais, Brazil, to estimate their home‐range sizes and population density, and describe their habitat use, natal dispersal behavior, and vocal behavior. We found an average density of 8.7 paired adults/km² in our study areas or 22.9 paired adults/km² when considering only used habitats. The sex ratio was male‐biased (males/total adults = 0.68), adults exhibited high site fidelity, home‐ranges averaged 4.0 ha (fixed kernel 95%) or 3.5 ha (95% minimum convex polygon) in size, and both sexes defended territories year‐round. We recorded four main types of songs, including two uttered more often during the breeding season. We monitored the natal dispersal of two males and one female who moved maximum distances of 1238 m, 780 m, and 1056 m, respectively, from natal areas. Our results confirm that Cipo Canasteros are restricted to the rocky‐outcrop habitat of the campos rupestres. In part due to their habitat specialization, Cipo Canasteros are considered Near Threatened, but other factors contributing to their demographic fragility include the small number, and probably low survival, of females and low reproductive success due to predation and brood parasitism by cowbirds. Given these threats, along with their specialized habitat and restricted range, the future conservation of Cipo Canasteros will likely depend on the extent to which their campos rupestres habitat can be conserved.     

Within‐year movements and site fidelity of Purple Sandpipers during the nonbreeding season

ABSTRACT Although within‐year site fidelity to specific wintering sites allows shorebirds to use prior knowledge of resources and microhabitats, such fidelity may also make populations more vulnerable to extirpation in the event of increased predation pressure, habitat loss, or disturbance. In the eastern Atlantic, Purple Sandpipers (Calidris maritima) have been found to be highly faithful to specific sites in wintering areas. However, little is known about the use of wintering areas by these sandpipers along the coast of Maine. We quantified movements of 60 radio‐marked Purple Sandpipers in a bay near the mainland and on an offshore cluster of islands along the mid‐coast of Maine during two winters (2005–2006 and 2006–2007). Birds marked in early‐ and mid‐December remained until spring migration, with no evidence of onward migration. Mean maximum distances moved did not differ significantly between either males (8.6 ± 1.0 [SE] km; N= 30) and females (7.4 ± 0.8 km; N= 30) or juveniles (9.9 ± 1.6 km; N= 9) and adults (7.8 ± 1.1 km; N= 26). We also detected no monthly (January–May) differences in maximum distances moved. Sixty percent of marked individuals moved ≤5 km between the two most distant relocations and no birds moved >25 km during the 2‐ to 4‐month tracking period. We attribute the high site fidelity primarily to the plentiful prey base in the study area. During a 2‐d period with severe cold, feeding areas at locations protected from wave action became encased in ice and birds at these locations moved up to 10 km offshore to sites with less ice. Species with strong site fidelity, like wintering Purple Sandpipers, may be at higher risk in the event of large‐scale changes in their food base, increased predation pressure, habitat loss, or disturbance. However, the short‐distance movements made when intertidal feeding areas became encased in ice suggest that Purple Sandpipers could potentially move greater distances in response to changing conditions in their wintering areas.     

Density‐dependent offspring interactions do not explain macroevolutionary scaling of adult size and offspring size

Most life forms exhibit a correlated evolution of adult size (AS) and size at independence (SI), giving rise to AS–SI scaling relationships. Theory suggests that scaling arises because relatively large adults have relatively high reproductive output, resulting in strong density‐dependent competition in early life, where large size at independence provides a competitive advantage to juveniles. The primary goal of our study is to test this density hypothesis, using large datasets that span the vertebrate tree of life (fishes, amphibians, reptiles, birds, and mammals). Our secondary goal is to motivate new hypotheses for AS–SI scaling by exploring how subtle variation in life‐histories among closely related species is associated with variation in scaling. Our phylogenetically informed comparisons do not support the density hypothesis. Instead, exploration of AS–SI scaling among life‐history variants suggests that steeper AS–SI scaling slopes are associated with evolutionary increases in size at independence. We suggest that a positive association between size at independence and juvenile growth rate may represent an important mechanism underlying AS–SI scaling, a mechanism that has been underappreciated by theorists. If faster juvenile growth is a consequence of evolutionary increases in size at independence, this may help offset the cost of delayed maturation, leading to steeper AS–SI scaling slopes.     

Low‐intensity microwave irradiation does not substantially alter gene expression in late larval and adult Caenorhabditis elegans

Reports that low‐intensity microwave radiation induces heat‐shock reporter gene expression in the nematode, Caenorhabditis elegans, have recently been reinterpreted as a subtle thermal effect caused by slight heating. This study used a microwave exposure system (1.0 GHz, 0.5 W power input; SAR 0.9–3 mW kg^?1 for 6‐well plates) that minimises temperature differentials between sham and exposed conditions (≤0.1 °C). Parallel measurement and simulation studies of SAR distribution within this exposure system are presented. We compared five Affymetrix gene arrays of pooled triplicate RNA populations from sham‐exposed L4/adult worms against five gene arrays of pooled RNA from microwave‐exposed worms (taken from the same source population in each run). No genes showed consistent expression changes across all five comparisons, and all expression changes appeared modest after normalisation (≤40% up‐ or down‐regulated). The number of statistically significant differences in gene expression (846) was less than the false‐positive rate expected by chance (1131). We conclude that the pattern of gene expression in L4/adult C. elegans is substantially unaffected by low‐intensity microwave radiation; the minor changes observed in this study could well be false positives. As a positive control, we compared RNA samples from N2 worms subjected to a mild heat‐shock treatment (30 °C) against controls at 26 °C (two gene arrays per condition). As expected, heat‐shock genes are strongly up‐regulated at 30 °C, particularly an hsp‐70 family member (C12C8.1) and hsp‐16.2. Under these heat‐shock conditions, we confirmed that an hsp‐16.2::GFP transgene was strongly up‐regulated, whereas two non‐heat‐inducible transgenes (daf‐16::GFP; cyp‐34A9::GFP) showed little change in expression. Bioelectromagnetics 30:602–612, 2009. © 2009 Wiley‐Liss, Inc.     

Foraging behavior of Cerulean Warblers during the breeding and non‐breeding seasons: evidence for the breeding currency hypothesis

Birds require additional resources for raising young, and the breeding currency hypothesis predicts that insectivorous species exploit large soft‐bodied prey during the breeding season, but shift to small, likely hard‐bodied, prey during the non‐breeding season. To test this hypothesis, we examined prey use by Cerulean Warblers (Setophaga cerulea), foliage‐gleaning Nearctic‐Neotropical migrants, during the breeding and non‐breeding seasons. We collected data on foraging behavior during the breeding season (including observations of prey items fed to young) in upland mixed‐oak forest in southeastern Ohio in 2009 and 2010 and, during the non‐breeding season, in shade coffee in the Cordillera de Merida, Venezuela, in 2008–2009. Cerulean Warblers captured 7% more large prey (visible prey extending beyond the bill) during the breeding than the non‐breeding season, but foraged at similar rates during both seasons. Large, soft‐bodied prey appeared to be especially important for feeding young. We found that adults delivered large prey on >50% of provisioning visits to nests and 69% of identifiable large prey fed to nestlings were greenish larvae (likely Lepidoptera or caterpillars) that camouflage against leaves where they would tend to be captured by foliage‐gleaning birds. Availability of specific taxa appeared to influence tree species foraging preferences. As reported by other researchers, we found that Cerulean Warblers selected trees in the genus Carya for foraging and our examination of caterpillar counts from the central Appalachian Mountains (Butler and Strazanac 2000 ) showed that caterpillars with greenish coloration, especially Baileya larvae, may be almost twice as abundant on Carya than Quercus. Our results provide evidence for the breeding currency hypothesis, and highlight the importance of caterpillars to a foliage‐gleaning migrant warbler of conservation concern.