The Influence of the California Marine Layer on Bill Size in a Generalist Songbird

Greenberg, Russell; Danner, Raymond M.

doi:10.1111/j.1558-5646.2012.01726.x

Cited by 52 publications

(91 citation statements)

References 43 publications

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“…For many birds, evaporative cooling via cutaneous and respiratory tissues is the primary means of dissipating heat, and can be more efficient than radiative and convective heat loss via the bill [48]. Heat loss may also be achieved through non-evaporative heat dissipation through the legs, and Allen's Rule predicts increases in leg size in relation to temperature [12,14]. Behavioural thermoregulation may also allow species to avoid exposure to hot conditions [49].…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, among 13 subspecies of the yellow warbler, Setophaga petechia, distributed throughout North and Central America, there was a strong positive relationship between bill size and ambient temperature in habitats experiencing mean maximum July (summer) temperatures in the range 18-41°C [11]. Larger bill size may be a particularly important adaptation in hot, arid environments where water availability is limited in summer [9,12,14] since heat dissipation via the bill does not involve evaporative water loss, thereby improving water conservation [2,[15][16][17]. However, in extremely hot environments large bill size may be costly due to the risk of heat uptake.…”

Section: Introductionmentioning

confidence: 99%

“…the cutting edge of the bill. Bill measurements were converted to an estimate of the surface area of the bill using the formula ((BW + BD)/4) × BL × π, which approximates lateral surface area of a nearly circular elliptical cone [14]. To estimate bill size relative to overall body size, we used an index of body size measured as the length of the flattened wing chord from the carpal joint to the tip of the longest primary (wing length is the best single linear predictor of structural body size [25]; see Additional file 1: Figure S2 for relative bill surface area of each species.…”

Section: Morphometric Measurementsmentioning

confidence: 99%

“…This suggests that there may be non-linear associations between temperature and optimal bill size. For instance, although relative bill size in song sparrows increased monotonically with ambient temperature across their range, bill size decreased in size in parts of their range where average summer temperatures exceeded body temperature, above about 36°C [14].…”

Section: Introductionmentioning

confidence: 99%

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Spatial variation in avian bill size is associated with humidity in summer among Australian passerines

Gardner

Symonds

Joseph

et al. 2016

Clim Chang Responses

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Background: Climate imposes multiple selection pressures on animal morphology. Allen's Rule proposes that geographic variation in the appendage size of endotherms, relative to body size, is linked to climatic variation, thereby facilitating heat exchange and body temperature regulation. Thus relatively larger appendages tend to be found in animals in warmer climates. Despite growing understanding of the role of the avian bill as an organ for heat exchange, few studies have tested the ecological significance of bill size for heat dissipation across species and environmental gradients. Amongst those that have, most have focused on the relationship with ambient temperature, but there is growing evidence that humidity also has a strong influence on heat dissipation. In particular, increasing humidity reduces the potential for evaporative cooling, favouring radiative and convective heat loss via the bill, and hence potentially favouring larger bills in humid environments. Here, we used phylogenetically-controlled analyses of the bill morphology of 36 species of Australian passerines to explore the relationship between bill size and multiple aspects of climate. Results: Humidity during the hot summer months (December-February) was positively associated with relative bill surface area across species. There was no overall association between bill size and summer temperatures per se, but the association with humidity was mediated by temperature, with a significant interaction indicating stronger associations with humidity at cooler summer temperatures. This is consistent with the idea that larger bills may become disadvantageous in humid conditions as ambient temperature approaches body temperature. Relative bill size was similar among closely related species, with phylogeny explaining 63.3% of the variance, and there was significant variation among species in their response to humidity. However, the relationship between relative bill size and humidity was not associated with phylogeny.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Morphometric Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spatial variation in avian bill size is associated with humidity in summer among Australian passerines

Gardner

Symonds

Joseph

et al. 2016

Clim Chang Responses

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“…Allen's rule is an eco-geographical hypothesis, relating climate to body size proportion in endotherms [15][16][17], and has been established within and among numerous avian groups [9,[18][19][20]. The rule proposes that protruding morphological features, such as limbs, digits and ears, vary in proportion to body mass, and to the environmental temperatures in which the animal normally resides.…”

Section: Introductionmentioning

confidence: 99%

Post-hatch heat warms adult beaks: irreversible physiological plasticity in Japanese quail

et al. 2013

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Across taxa, the early rearing environment contributes to adult morphological and physiological variation. For example, in birds, environmental temperature plays a key role in shaping bill size and clinal trends across latitudinal/thermal gradients. Such patterns support the role of the bill as a thermal window and in thermal balance. It remains unknown whether bill size and thermal function are reversibly plastic. We raised Japanese quail in warm (308C) or cold (158C) environments and then at a common intermediate temperature. We predicted that birds raised in cold temperatures would develop smaller bills than warm-reared individuals, and that regulation of blood flow to the bill in response to changing temperatures would parallel the bill's role in thermal balance. Cold-reared birds developed shorter bills, although bill size exhibited 'catch-up' growth once adults were placed at a common temperature. Despite having lived in a common thermal environment as adults, individuals that were initially reared in the warmth had higher bill surface temperatures than coldreared individuals, particularly under cold conditions. This suggests that blood vessel density and/or the control over blood flow in the bill retained a memory of early thermal ontogeny. We conclude that post-hatch temperature reversibly affects adult bill morphology but irreversibly influences the thermal physiological role of bills and may play an underappreciated role in avian energetics.

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Morphological diversity and altitudinal differentiation of Aethopyga species

Lu,

Shao,

et al. 2023

Ecology and Evolution

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The morphological characteristics of birds are an important tool for studying their adaptation and evolution. The morphological evolution of a clade is not only constrained by the phylogenetic relationship, but also influenced by ecological factors and interspecific competition. Aethopyga is a group of small nectar‐eating birds with obvious sexual dimorphism. They have slender and decurved beaks, which reflect their unique diet and foraging mode. Traditional and geometric morphometrics were combined to characterize the body morphology and beak shape of six species of Aethopyga distributed in China. We aim to assess the roles of phylogeny, altitude, and species interactions to morphological evolution. The main distinguishing characteristic among these six species were overall body size, the ratio of body weight, culmen and tarsal length to body length, tail length and wing length, and beak shape (slender/straight vs. thick/decurved). Although these dimensions cannot distinguish all species, they can show a clear distribution trend, and there is a significant Mahalanobis distance between each pair of species. There were no significant phylogenetic signals in morphological traits. The results of PGLS analysis show that altitude is significantly correlated with log‐transformed tarsus length and beak‐shaped PC1 (slender/straight vs thick/decurved dimensions) across the six species analyzed. Mantel test shows that the distance matrix of beak morphological characteristics showed a significant correlation with the altitudinal distance matrix. The results indicated no significant phylogenetic signal in the morphological characteristics of six species. In terms of beak shape, species with greater overlap in elevation distribution have more similar morphological characteristics, that is, less morphological differentiation.

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The Influence of the California Marine Layer on Bill Size in a Generalist Songbird

Cited by 52 publications

References 43 publications

Spatial variation in avian bill size is associated with humidity in summer among Australian passerines

Spatial variation in avian bill size is associated with humidity in summer among Australian passerines

Post-hatch heat warms adult beaks: irreversible physiological plasticity in Japanese quail

Morphological diversity and altitudinal differentiation of Aethopyga species

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