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Ancient Arctic Nursery: 73 Million-Year-Old Bird Fossils Discovered in Alaska

For half of the time birds have existed on Earth – a staggering 150 million years – they’ve been nesting in the Arctic, according to a groundbreaking paper featured in Science. The study reveals that millions of birds gathered in the polar regions 73 million years ago, raising their young amidst dinosaurs and other prehistoric creatures.

The research, led by Lauren Wilson from Princeton University, is based on dozens of tiny fossilized bones and teeth found at an Alaska excavation site. These ancient bird fossils, which include diving birds resembling loons, gull-like birds, and various types of ducks and geese, push back the record of birds breeding in the polar regions by 25 to 30 million years.

Prior to this study, the earliest known evidence of birds reproducing in either the Arctic or Antarctic was about 47 million years ago. This new discovery sheds light on the evolution of modern bird species and highlights the importance of the Arctic as a nursery for these animals.

The fossil collection is part of the University of Alaska Museum of the North’s collections, and the research team used an uncommon excavation and analysis approach to recover the tiny bones and teeth. By examining every bone and tooth they could find, from the visible to the microscopic, the scientists were able to identify multiple types of birds that coexisted with dinosaurs in the Arctic.

This study has significant implications for our understanding of bird evolution and the behavior of ancient species. As Pat Druckenmiller, senior author of the paper and director of the University of Alaska Museum of the North, notes, “The Arctic is considered the nursery for modern birds. It’s kind of cool when you go to Creamer’s Field [a Fairbanks-area stopover for migrating geese, ducks, and cranes] to know that they have been doing this for 73 million years.”

While further research is needed to confirm whether these ancient bird fossils belong to the Neornithes group (which includes all modern birds), this study has already pushed back the record of birds breeding in the polar regions by millions of years. The findings are a testament to the value of an uncommon approach to fossil hunting and highlight the importance of continued research into the evolution and behavior of ancient species.

The study of isotopes has revolutionized our understanding of the natural world. By using these unique fingerprints, scientists can identify where and when something lived, what it ate, and even what the environment was like at that time. According to University of Cincinnati Professor Brooke Crowley, “Isotopic analysis is coming into its heyday.” This surge in research has led to a plethora of creative applications for isotopic analysis.

In Crowley’s Stable Isotope Ecology course, students are encouraged to come up with innovative questions and projects related to isotopic analysis. For instance, they might investigate whether shade-grown coffee or free-range chickens produce different isotopic signatures compared to their counterparts. One such study published in the journal Ecology and Evolution explored the impact of digestion on the ratios of isotopes.

The research team, led by UC graduate Maddie Greenwood, collected droppings and regurgitated pellets from captive Eurasian eagle owls and red-tailed hawks at the Cincinnati Zoo & Botanical Garden. These birds subsist on a diet of frozen rats, which helps to break down bone in their digestive system. The researchers compared the ratios of carbon, nitrogen, oxygen, and strontium isotopes in the rats to those found in the bird poop and pellets.

The results were unexpected, with significant differences observed between the isotopic signatures of the rat bones and the owl pellets. This discovery has significant implications for scientists using rodent bones to establish what environmental conditions were like in the past or infer prey locations. The study warns researchers to exercise caution when using potentially digested bone for these purposes.

The lead author, Maddie Greenwood, highlights the importance of isotopic analysis in understanding the natural world. “This is incredibly rewarding… We figure out new ways to use this tool and new ways to make it helpful.” Crowley emphasizes that more work needs to be done to fully understand the impact of digestion on molecular analysis of owl pellets.

As scientists increasingly turn to isotopes in poop to study wild animals, this study serves as a reminder to consider the potential effects of digestion on their findings. By acknowledging these limitations, researchers can refine their methods and provide more accurate insights into the natural world.

As scientists at the University of Massachusetts Amherst recently revealed, they have made a groundbreaking discovery in the world of birdsong evolution. By analyzing the amplitude (volume) and frequency (pitch) of over 1,000 songs from 53 species of birds, researchers were able to shed new light on how these vocalizations relate to each other.

For years, biologists have debated whether birds can control their pitch as they get louder or if their vocal abilities are mechanically limited. The study published in Proceedings B has finally provided the answer we’ve been searching for.

Imagine you’re at an outdoor concert, trying to yell across a few rows to your friends. As you speak louder, your voice increases not only in volume but also in frequency, becoming higher-pitched. However, the low bass frequencies can be heard from a great distance, while the higher trebly voices and instruments fade away.

This phenomenon has puzzled researchers for decades, with two opposing camps: those who believe birds are mechanically constrained and others who argue that evolution would favor lower sounds carrying farther to increase their chance of being heard. The new study put this debate to rest by revealing a complex relationship between volume and pitch in the world of birdsong.

Researchers João C. T. Menezes and Jeffrey Podos, along with their team, extensively sampled songs from various species, including the Canada goose and the elusive black-and-gold cotinga from Brazil. What they found was surprising: among the 53 species studied, 27 had calls that got higher pitched as they got louder, while 12 species showed lower-pitched sounds when increasing volume.

Moreover, the team discovered that songbirds tend to narrow their range of frequencies used as their volume increases, indicating an ability to control the tension of their vocal apparatus. This unique specialization could have given them more evolutionary freedom in developing their songs.

So, what’s the takeaway from this study? It seems we can’t simply point our finger at either physiology or evolution as the explanation for how birds’ calls work. Instead, it appears that both factors play a role in shaping the complex relationship between volume and pitch in the world of birdsong.

Next time you find yourself listening to the birds, take a moment to appreciate the dynamic interplay between pitch and volume – a testament to the intricate wonders of nature.