This 1 December 2020 video says about itself:
The Linnean Society of London publishes three peer-reviewed scientific journals in biology, botany and zoology. The journals cover original scientific papers and studies.
This 5 November 2020 video says about itself:
The Evolution of Hummingbirds
Today, hummingbirds are only found in north and south America but over 30 million years ago a hummingbird lived in southern Germany, and is the oldest known fossil of a hummingbird known. How did it get there and how did hummingbirds evolve to hover and live off nectar?
This video from the USA says about itself:
Hummingbirds Aflutter In The Davis Mountains – August 25, 2020
Tiny hummingbirds buzz through the West Texas feeder cam site in the Davis Mountains. This site sits along the migration routes of more than 10 different species of hummingbirds.
This 2014 video says about itself:
Baby Rufous hummingbirds life cycle. Chapter 1
The life cycle of Rufous chicks. From nest building to raising and teaching and caring for their young. Same video on my channel with hummer sounds.
From Oregon State University in the USA:
For rufous hummingbirds, migration looks different depending on age and sex
July 28, 2020
Plucky, beautiful and declining in numbers at about a 2% annual rate, the rufous hummingbird makes its long annual migration in different timing and route patterns based the birds’ age and sex, new research by Oregon State University shows.
The findings, published in the journal Avian Conservation & Ecology, are important because the more that is known about how rufous hummingbirds migrate, the more that can be done to ensure birds of different ages and sexes have the resources they need each year on their journey up and down the western part of North America.
“Different age-sex categories of rufous hummingbirds use alternative routes and differ in migration cycles and distributions,” said the study’s corresponding author, Jose?e Rousseau, a Ph.D. candidate in the OSU College of Forestry. “Our results seem to indicate that the age-sex categories could be affected in different ways by things like habitat loss and climate during migration. If we keep that in mind, we can make conservation efforts that help these amazingly feisty little creatures — and I describe them that way with the utmost respect — have the resources they need during their migration across the landscape.”
With a reputation as one of the continent’s most determined and assertive birds, the rufous hummingbird, scientifically known as Selasphorus rufus, weighs less than a nickel and tops out at about 3 inches long. Based on its body length, its migratory journey is one of the world’s longest — the hummingbirds that travel the full extent of the range, from Alaska to Mexico, migrate almost 80 million body lengths, or 3,900 miles.
By comparison, an arctic tern covers about 51 million body lengths on the 13-inch bird’s one-way flight of 11,000 miles.
Rufous hummingbirds live in open woodlands, nest in trees and eat nectar. A common visitor to bird feeders, the extremely territorial rufous hummingbird will chase away much larger species of hummingbirds, and they’ll even drive squirrels away from their nesting areas.
Equipped with excellent memories, rufous hummingbirds will visit the same feeders over multiple years, even looking for food at former locations of feeders that have been moved.
The study by scientists in the Oregon State University College of Forestry and at the Klamath Bird Observatory in Ashland looked at 15 years’ worth of fall migration banding data involving nearly 30,000 hummingbird captures at more than 450 locations.
The research showed that adult females tended to have a southbound migration route that was parallel to and between those of young and adult males, Rousseau said.
“Also, a greater number of young birds migrated south through California in comparison to adult females and adult males,” she said. “Our results suggest that the migration of each age-sex category is separated by about two weeks, with adult males migrating first, followed by adult females, and then the young of both sexes. Interestingly, though, migration speed was not statistically different among the categories.”
The adult males were captured within a smaller geographic distribution during any given week of migration compared with adult females and young birds, she added.
Collaborating with Rousseau on the study were Matt Betts of the OSU College of Forestry and John Alexander of the Klamath Bird Observatory.
The Natural Sciences and Engineering Research Council, the National Science Foundation, the Western Hummingbird Partnership, the U.S. Forest Service and the OSU Richardson Family Graduate Fellowship supported the research.
This 14 July 2020 video from the USA says about itself:
A male Black-chinned, male Broad-tailed, and female Lucifer Hummingbird all visit the center feeder on the West Texas Hummingbird cam. More than a dozen different species of hummingbirds are known to make their way through this area of the Davis Mountains, and may even stop in front of the cam, at the height of migration activity.
This video from the USA says about itself:
Praying Mantis Visits Hummingbird Feeder In West Texas – June 25, 2020
A praying mantis drops down to the hummingbird feeders and scuttles from port to port, likely in search of an insect [bee] meal. In rare cases, larger mantids have been documented staking out hummingbird feeders and preying on the birds that visit, but this individual is too small to be a risk to the birds.
This 21 June 2020 video is about hummingbird evolution.
This 2018 video is called Beautiful hummingbirds show off their breathtaking colors.
From Princeton University in the USA:
Spectacular bird’s-eye view? Hummingbirds see diverse colors humans can only imagine
Team trains wild hummingbirds to discriminate UV color combinations
June 15, 2020
Summary: While humans have three color cones in the retina sensitive to red, green and blue light, birds have a fourth color cone that can detect ultraviolet light. A research team trained wild hummingbirds to perform a series of experiments that revealed that the tiny birds also see combination colors like ultraviolet+green and ultraviolet+red.
To find food, dazzle mates, escape predators and navigate diverse terrain, birds rely on their excellent color vision.
“Humans are color-blind compared to birds and many other animals,” said Mary Caswell Stoddard, an assistant professor in the Princeton University Department of Ecology and Evolutionary Biology. Humans have three types of color-sensitive cones in their eyes — attuned to red, green and blue light — but birds have a fourth type, sensitive to ultraviolet light. “Not only does having a fourth color cone type extend the range of bird-visible colors into the UV, it potentially allows birds to perceive combination colors like ultraviolet+green and ultraviolet+red — but this has been hard to test,” said Stoddard.
To investigate how birds perceive their colorful world, Stoddard and her research team established a new field system for exploring bird color vision in a natural setting. Working at the Rocky Mountain Biological Laboratory (RMBL) in Gothic, Colorado, the researchers trained wild broad-tailed hummingbirds (Selasphorus platycercus) to participate in color vision experiments.
“Most detailed perceptual experiments on birds are performed in the lab, but we risk missing the bigger picture of how birds really use color vision in their daily lives,” Stoddard said. “Hummingbirds are perfect for studying color vision in the wild. These sugar fiends have evolved to respond to flower colors that advertise a nectar reward, so they can learn color associations rapidly and with little training.”
Stoddard’s team was particularly interested in “nonspectral” color combinations, which involve hues from widely separated parts of the color spectrum, as opposed to blends of neighboring colors like teal (blue-green) or yellow (green-red). For humans, purple is the clearest example of a nonspectral color. Technically, purple is not in the rainbow: it arises when our blue (short-wave) and red (long-wave) cones are stimulated, but not green (medium-wave) cones.
While humans have just one nonspectral color — purple, birds can theoretically see up to five: purple, ultraviolet+red, ultraviolet+green, ultraviolet+yellow and ultraviolet+purple.
Stoddard and her colleagues designed a series of experiments to test whether hummingbirds can see these nonspectral colors. Their results appear June 15 in the Proceedings of the National Academy of Sciences.
The research team, which included scientists from Princeton, the University of British Columbia (UBC), Harvard University, University of Maryland and RMBL, performed outdoor experiments each summer for three years. First they built a pair of custom “bird vision” LED tubes programmed to display a broad range of colors, including nonspectral colors like ultraviolet+green. Next, they performed experiments in an alpine meadow frequently visited by local broad-tailed hummingbirds, which breed at the high-altitude site.
Each morning, the researchers rose before dawn and set up two feeders: one containing sugar water and the other plain water. Beside each feeder, they placed an LED tube. The tube beside the sugar water emitted one color, while the one next to the plain water emitted a different color. The researchers periodically swapped the positions of the rewarding and unrewarding tubes, so the birds could not simply use location to pinpoint a sweet treat. They also performed control experiments to ensure that the tiny birds were not using smell or another inadvertent cue to find the reward. Over the course of several hours, wild hummingbirds learned to visit the rewarding color. Using this setup, the researchers recorded over 6,000 feeder visits in a series of 19 experiments.
The experiments revealed that hummingbirds can see a variety of nonspectral colors, including purple, ultraviolet+green, ultraviolet+red and ultraviolet+yellow. For example, hummingbirds readily distinguished ultraviolet+green from pure ultraviolet or pure green, and they discriminated between two different mixtures of ultraviolet+red light — one redder, one less so.
“It was amazing to watch,” said Harold Eyster, a UBC Ph.D. student and a co-author of the study. “The ultraviolet+green light and green light looked identical to us, but the hummingbirds kept correctly choosing the ultraviolet+green light associated with sugar water. Our experiments enabled us to get a sneak peek into what the world looks like to a hummingbird.”
Even though hummingbirds can perceive nonspectral colors, appreciating how these colors appear to birds can be difficult. “It is impossible to really know how the birds perceive these colors. Is ultraviolet+red a mix of those colors, or an entirely new color? We can only speculate,” said Ben Hogan, a postdoctoral research associate at Princeton and a co-author of the study.
“To imagine an extra dimension of color vision — that is the thrill and challenge of studying how avian perception works,” said Stoddard. “Fortunately, the hummingbirds reveal that they can see things we cannot.”
“The colors that we see in the fields of wildflowers at our study site, the wildflower capital of Colorado, are stunning to us, but just imagine what those flowers look like to birds with that extra sensory dimension,” said co-author David Inouye, who is affiliated with the University of Maryland and RMBL.
Finally, the research team analyzed a data set of 3,315 feather and plant colors. They discovered that birds likely perceive many of these colors as nonspectral, while humans do not. That said, the researchers emphasize that nonspectral colors are probably not particularly special relative to other colors. The wide variety of nonspectral colors available to birds is the result of their ancient four color-cone visual system.
“Tetrachromacy — having four color cone types — evolved in early vertebrates,” said Stoddard. “This color vision system is the norm for birds, many fish and reptiles, and it almost certainly existed in dinosaurs. We think the ability to perceive many nonspectral colors is not just a feat of hummingbirds but a widespread feature of animal color vision.”