Background Research on variation in bill morphology has focused the role of diet. Bills have other functions, however, including a heat and water balance. The loss may be particularly important birds where is limiting. Song sparrows localized coastal dunes salt marsh edge (Melospiza melodia atlantica) are similar size to, but bills with 17% greater surface area than, those that live mesic habitats (M. m. melodia), pattern shared sparrows. We tested hypotheses can use their to dissipate "dry"...

In addition to the observed high diversity of species in tropics, divergence among populations same exists over short geographic distances both phenotypic traits and neutral genetic markers. Divergence suggests great potential for evolution reproductive isolation eventual speciation. birds, song can evolve quickly through cultural transmission result regional dialects, which be a critical component variation female preference. We examined male behavioral responses local nonlocal dialects two...

Physiological factors are rarely proposed to account for variation in the morphology of feeding structures. Recently, bird bills have been demonstrated be important convective and radiant heat sinks. Larger greater surface area than smaller could serve as more effective thermoregulatory organs under hot conditions. The radiating function should open habitats with little shade stronger winds. Furthermore, a means dumping without increasing water loss through evaporation, might play...

Soundscapes pose both evolutionarily recent and long-standing sources of selection on acoustic communication. We currently know more about the impact human-generated noise communication than we do how natural sounds such as pounding surf have shaped signals over evolutionary time. Based signal detection theory, hypothesized that phenotypes will vary with anthropogenic background levels similar mechanisms cultural evolution and/or behavioral flexibility may underlie this variation. studied...

Abstract Aim Bill size is positively correlated with average air temperature in several avian taxa. The conventional explanation for this pattern that the poorly insulated surface area of bill functions to dissipate excess heat hot climates or retain cold (Allen's rule). We hypothesize applicability Allen's rule depends upon season critical thermal stress, which may vary by location and species. previously found increases high summer song sparrows ( Melospiza melodia ) California, supporting...

Abstract Heat waves cause mass mortality of animals, including humans, across the globe annually, which has drawn new attention to how animals cope with high air temperatures. Recent field research explored behavioral responses temperatures, can influence reproductive success and mortality. Less well studied are effects temperatures on cognition, may underlie changes. Specifically, it is poorly known if cognitive declines occur at motor components behavior similarly affected. We tested zebra...

Abstract We tested the behavioral responses of breeding Sternula antillarum (Least Terns) to pedestrians and off-road vehicles show that disturbance source, intra-colony characteristics, environmental factors all influenced distance, at which birds were disturbed, as well duration their response. Our goal was inform wildlife buffer distances used protect S. Cape Hatteras National Seashore, North Carolina beyond. measured during routine activities 8 colonies experimental 3 colonies....

The hypothesis is tested that birds in hotter and drier environments may have larger bills to increase the surface area for heat dissipation. California provides a climatic gradient test influence of climate on bill size. Much experiences dry warm/hot summers coastal areas experience cooler than interior localities. Based measurements from 1488 museum skins, song sparrows showed increasing body-size-corrected coast declining far eastern desert. As predicted by Newton's convective transfer...

Abstract Darwin's finches have been the focus of intense study demonstrating how climatic fluctuations coupled with resource competition drive evolution a variety bill sizes and shapes. The bill, as other peripheral surfaces, also plays an important role in thermoregulation numerous bird species. avian is vascularized, while limbs specialized vasculature that facilitate heat loss or conservation (i.e. they are thermoregulatory windows). Galápagos Islands, home to finches, hot relatively dry...

Anthropogenic noise imposes novel selection pressures, especially on species that communicate acoustically. Many animals—including insects, frogs, whales and birds—produce sounds at higher frequencies in areas with low-frequency pollution. Although there is support for animals changing their vocalizations real time response to (i.e. immediate flexibility), other evolutionary mechanisms learn remain largely unexplored. We hypothesize cultural signal structures less masked by a mechanism of...

Abstract The soundscape acts as a selective agent on organisms that use acoustic signals to communicate. A number of studies document variation in structure, amplitude, or timing signal production correspondence with environmental noise levels thus supporting the hypothesis are changing their signaling behaviors avoid masking. time scale at which respond is particular interest. Signal structure may evolve across generations through processes such cultural genetic transmission. Individuals...

Abstract Background noise can interfere with acoustic communication. Signal modifications have the potential to increase signal‐to‐noise ratios and reduce masking effect of noise. Immediate signaling flexibility, a type vocal plasticity, allows animals modify their signal optimize transmission depending on ambient conditions. Results from previous studies provide conflicting evidence about whether expression immediate flexibility is dependent upon signaler having prior experience noisy...

Abstract Bill size is often viewed as a species‐specific adaptation for feeding, but it sometimes varies between sexes, suggesting that sexual selection or intersexual competition may also be important. Hypotheses to explain dimorphism in avian bill include divergence feeding niche thermoregulatory demands, intrasexual based on increased among males, female preference. Birds show seasonal changes due shifts the balance growth rate and wear, which diet endogenous rhythms growth. Insight into...

Sexual size dimorphism is expected to be more pronounced in vertebrates on islands, particularly trophic characters, as a response decreased interspecific competition for food. We found (based measurements of 1423 museum specimens) that bill was greater island than mainland populations song sparrows. However, varied among islands and positively correlated with high summer temperature size. Island sparrow bills follow the overall positive relationship California sparrows, which includes...

Summary Moult is critical for fitness many organisms several reasons: it allows growth and maintains the function of integument protection, thermoregulation communication. Feather moult in birds costly therefore typically does not overlap with migration or reproduction. In spring, rapid succession pre‐alternate moult, (if a migrant) breeding suggests that timing could constrain initiation breeding. A trade‐off between time spent moulting might also limit quality. The proximate basis well...

We used thermal imaging to show that two environmental factors - acute stress and diet influence thermoregulatory performance of a known window, the avian bill. The bill plays important roles in thermoregulation water balance. Given heat loss through is adjustable vasoconstriction vasodilation, can cause peripheral body surfaces, we hypothesized may bill's role as window. further influences dissipation from bill, given condition surface temperature another region (the eye region). measured...

We determined prevalence to feline immunodeficiency virus (FIV) antibodies, leukemia (FeLV) antigen, and Toxoplasma gondii antibodies in feral cats (Felis catus) on Mauna Kea Hawaii from April 2002 May 2004. Six of 68 (8.8%) 11 (16.2%) were antibody positive FIV antigen for FeLV, respectively; 25 67 (37.3%) seropositive T. gondii. Antibodies FeLV occurred all age sex classes, but only adult males. Evidence current or previous infections with two these infectious agents was detected eight 64...

We used high precision computed tomography (CT) and traditional radiography to study the nasal conchae, complex structures within cavity that condition air via countercurrent heat exchange. Air conditioning in conchae assists thermoregulation water balance, both of which pose challenges for many birds. hypothesized hot water-limited environments would select larger or more maximize moisture recapture during exhalation turn cause evolution deeper wider bills. provide first intraspecific...

ABSTRACT Inferring the environmental selection pressures responsible for phenotypic variation is a challenge in adaptation studies as traits often have multiple functions and are shaped by complex regimes. We provide indirect evidence that morphology of multifunctional avian bill primarily climate thermoregulatory ability Melospiza melodia (Song Sparrow) on California Channel Islands. Our research builds study M. museum specimens demonstrated positive correlation between surface area maximum...

The Winter Food Limitation Hypothesis (WFLH) states that winter food abundance is a dominant source of population limitation migratory birds. Evidence accumulating long-distance birds wintering in tropical climates have high overwinter survival probabilities and mainly affects their fitness nonlethally by limiting energetic reserves necessary for successful reproduction. In contrast, the relative roles direct mortality vs. indirect effects caused not been investigated thoroughly on...

Temperature and water availability affect the survival, reproductive success, behavior of all animals; thus, traits that influence thermoregulation balance should be under strong selection. Avian bills can dissipate excess body heat through convection radiation. We hypothesized in hot, dry locations, bill size would selected for its value thermoregulation: males with larger shed more efficiently, allowing greater activity levels during thermally challenging periods breeding season. predicted...

Feral cats Felis catus in dry subalpine woodland of Mauna Kea, Hawai?i, live low density and exhibit some the largest reported home ranges literature. While 95% fixed kernel range estimates for three females averaged 772 ha, four males 1 418 one male maintained a 2 050 ha. Mean daily movement rates between sexes overlapped widely did not differ significantly (P = 0.083). Log-transformed were larger than those 0.024), but 25% 0.017). Moreover, log-transformed also this seven other studies...

Background: Research on variation in bill morphology has focused the role of diet.Bills have other functions, however, including a heat and water balance.The loss may be particularly important birds where is limiting.Song sparrows localized coastal dunes salt marsh edge (Melospiza melodia atlantica) are similar size to, but bills with 17% greater surface area than, those that live mesic habitats (M.m. melodia), pattern shared sparrows.We tested hypotheses can use their to dissipate ''dry''...

Anthropogenic noise presents a problem for acoustic communication in animal taxa around the world. Many animals respond by modifying their signals, sometimes along multiple axes, such as song structure, redundancy, or amplitude. To date, no study has assayed relative response of to axes signal variation, structure and amplitude, associated with anthropogenic levels. investigate impact potential adaptations on targeted receivers, we manipulated amplitude minimum frequency white-crowned...