scholarly journals Testing the shared‐pathway hypothesis in the carotenoid‐based coloration of red crossbills

Evolution ◽  
2020 ◽  
Vol 74 (10) ◽  
pp. 2348-2364 ◽  
Author(s):  
Alejandro Cantarero ◽  
Rafael Mateo ◽  
Pablo R Camarero ◽  
Daniel Alonso ◽  
Blanca Fernandez‐Eslava ◽  
...  
Keyword(s):  
Red Crossbills

scholarly journals Seasonal Patterns of Fat Deposits in Relation to Migratory Strategy in Facultative Migrants

2021 ◽  
Vol 9 ◽  
Author(s):  
Jamie M. Cornelius ◽  
Thomas P. Hahn ◽  
Ashley R. Robart ◽  
Ben J. Vernasco ◽  
Dorothy L. Zahor ◽  
...  
Keyword(s):  
Wing Loading ◽  
Long Distance ◽  
Flight Duration ◽  
House Finches ◽  
Fat Deposits ◽  
Migratory Season ◽  
Partial Migrant ◽  
Migration Strategies ◽  
Migratory Strategy ◽  
Red Crossbills

Physiological preparations for migration generally reflect migratory strategy. Migrant birds fuel long-distance flight primarily with lipids, but carrying excess fuel is costly; thus, the amount of fat deposited prior to departure often reflects the anticipated flight duration or distance between refueling bouts. Seasonal pre-migratory deposition of fat is well documented in regular seasonal migrants, but is less described for more facultative species. We analyze fat deposits of free-living birds across several taxa of facultative migrants in the songbird subfamily Carduelinae, including house finches (Haemorhous mexicanus), American goldfinches (Spinus tristis), pine siskins (Spinus pinus) and four different North American ecotypes of red crossbills (Loxia curvirostra), to evaluate seasonal fat deposition during facultative migratory periods. Our data suggest that the extent of seasonal fat deposits corresponds with migratory tendency in these facultative taxa. Specifically, nomadic red crossbills with a seasonally predictable annual movement demonstrated relatively large seasonal fat deposits coincident with the migratory periods. In contrast, pine siskins, thought to be more variable in timing and initiation of nomadic movements, had smaller peaks in fat deposits during the migratory season, and the partial migrant American goldfinch and the resident house finch showed no peaks coincident with migratory periods. Within the red crossbills, those ecotypes that are closely associated with pine habitats showed larger peaks in fat deposits coincident with autumn migratory periods and had higher wing loading, whereas those ecotypes associated with spruces, Douglas-fir and hemlocks showed larger peaks coincident with spring migratory periods and lower wing loading. We conclude that population averages of fat deposits do reflect facultative migration strategies in these species, as well as the winter thermogenic challenges at the study locations. A difference in seasonal fattening and wing loading among red crossbill ecotypes is consistent with the possibility that they differ in their migratory biology, and we discuss these differences in light of crossbill reproductive schedules and phenologies of different conifer species.

scholarly journals Assortative flocking in crossbills and implications for ecological speciation

2012 ◽  
Vol 279 (1745) ◽  
pp. 4223-4229 ◽  
Author(s):  
Julie W. Smith ◽  
Stephanie M. Sjoberg ◽  
Matthew C. Mueller ◽  
Craig W. Benkman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Ecological Speciation ◽  
Central Question ◽  
Loxia Curvirostra ◽  
Call Type ◽  
Divergent Natural Selection ◽  
Contact Calls ◽  
Red Crossbills

How reproductive isolation is related to divergent natural selection is a central question in speciation. Here, we focus on several ecologically specialized taxa or ‘call types’ of red crossbills ( Loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. Call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. We found that two call types of red crossbills were more likely to approach playbacks of their own call type than those of heterotypics, and that their propensity to approach heterotypics decreased with increasing divergence in bill size. Although call similarity also decreased with increasing divergence in bill size, comparisons of responses to familiar versus unfamiliar call types indicate that the decrease in the propensity to approach heterotypics with increasing divergence in bill size was a learned response, and not a by-product of calls diverging pleiotropically as bill size diverged. Because crossbills choose mates while in flocks, assortative flocking could lead indirectly to assortative mating as a by-product. These patterns of association therefore provide a mechanism by which increasing divergent selection can lead to increasing reproductive isolation.

scholarly journals Confiding Young Red Crossbills

Blue Jay ◽  
1960 ◽  
Vol 18 (4) ◽  
Author(s):  
J. Gunn
Keyword(s):  
Red Crossbills

scholarly journals Red Crossbills

Blue Jay ◽  
1951 ◽  
Vol 9 (3) ◽  
Author(s):  
L. T. McKim
Keyword(s):  
Red Crossbills
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