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Anna's #Hummingbirds #Calypte #anna (#Trochilidae) were able to expand northward by taking advantage of #humanaltered #environments. #Anthropogenic #influences on the #evolutionarychanges of #species can often be demonstrated, both directly and indirectly. For instance the consequences of human-made #globalwarming are clearly observable in Germany; numerous species native to the Mediterranean have independently expanded northward, such as the white-spotted rose beetle #Oxythyrea #funesta (Scarabaeidae), and have evidently undergone evolutionary adaptation to winters that remain relatively cold in their new region. Humans exert a more direct influence when they intentionally introduce animal or plant species outside their natural ranges, such as the Asian lady beetle #Harmonia #axyridis (Coccinellidae). Through #geneticrecombination resulting from the interbreeding of previously separate breeding lineages, this beetle developed greater #geneticvariability than found in its native range with enhanced adaptability to new environmental conditions, e.g. new defensive #behavior. Furthermore, human expansion has created artificial habitats for species that were not originally native. In the Western world, for example, the #housemouse Mus musculus (originating in the steppes of India) and the #brownrat Rattus norvegicus (originating in regions of East Asia) have become dependent on human settlements, a shift that has resulted in evolutionary changes. For example the house mouse has adapted its dental morphology and digestive tract to new dietary conditions. But how quickly can species undergo distinct morphological changes once they have colonized new habitats due to human influence? N. M. Alexandre et al. (2025) investigated this for #Annashummingbird using #museumspecimens and data from the Audubon Christmas Bird Count, an annual #birdcensus. They correlated their data with historical records regarding the growing popularity of artificial #hummingbirdfeeders. Based on these findings, they were able to demonstrate that the hummingbird's northward expansion is attributable to both increased #eucalyptusplanting and the ever-growing popularity of hummingbird feeders. In a sense, the species has become a #humancommensal, able to survive in previously inhospitable habitats solely due to conditions created by humans. Moreover, they adapted their #beakmorphology through #evolution, and did so at a demonstrably #rapidpace, specifically within a twenty-year period between 1930 and 1950. Within their original range, beaks became longer and larger in areas with many feeders, allowing the birds to consume more food. Conversely, in areas north of the original range, beaks became shorter to facilitate more efficient #thermoregulation in the colder climate. How does one actually feed a hummingbird? A sugar solution, which must mimic the natural composition of nectar, is provided in a plastic or glass reservoir. The birds can then consume this solution from an open trough, for example. The reddish color plays a crucial role here; hummingbirds respond strongly to red, pink, and orange because reddish hues absorb ultraviolet light, making them stand out sharply against the green background. Unlike natural food plants, such as the California fuchsia #Epilobium #canum, the food supply around an artificial feeder is far less limited, leading to greater #competition for the resource among hummingbirds. According to the authors, hummingbirds have also adapted morphologically in this regard: in areas with many feeding sites, their beaks have become sharper and more pointed to better compete for resources. © StefanFWirth, June 2026, Berlin Reference: N. M. Alexandre et al. (2025): https://t.co/CQOU89KLmC #Illustrations: © Stefan F. Wirth, June 2026, Berlin; AI-assisted, based on my hand-drawn sketches, manually edited: 1) Anna's hummingbirds feeding on nectar from Zauschneria californica blossoms 2) Anna's hummingbirds at feeding station

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