Written by: Jorge Gonzalez
Dinosaurs inhabited the Earth millions of years ago. Pictured to the right is an artistic description of a species of Sauropod, a group of long necked, long tailed, four legged herbivorous dinosaurs. Not much is known of dinosaurs engaging in migratory behaviors similar to those that many birds display.
Migration is defined as seasonal movement from one region to another. Movement can be within states, countries, and continents. There are many reasons why today’s animals would migrate.
However, there is little evidence to conclude that dinosaurs migrated for any one reason. Scientists would be able to use this information to learn more about dinosaur movement during a period when the planet had less, but larger masses of land pieced together.
According to a 2011 study conducted by Henry Fricke, Justin Hencecroth, and Marie Hoerner, Camarasaurus sp. is believed to be able to undertake long seasonal migrations. But, it does not mean that Camarasaurus did or that they ever had to migrate. Fricke, Hencecroth, and Hoerner looked at oxygen isotope ratios in teeth-enamel and compared them to those of ancient soil, lake and wetland carbonates in lowland settings.
Oxygen values would vary significantly over different landscapes due to differences in aridity and elevation. Teeth enamel increases in age from bottom to top. This means that the lowest oxygen isotope ratios are found at the youngest teeth. Fricke and his colleagues found that differing oxygen ratios in the enamel meant that Camarasaurus sp. were leaving their regular basin areas and seeking high elevation. It is believed that they left the basin during dry seasons when food and water was scarce.
This behavior of traveling large distances in search of resources can be considered as seasonal migration. It may have been driven by an environmental stress rather than instinct. This new information is instrumental in furthering the knowledge of behaviors and traveling patterns that these incredible animals had to undertake in their time periods.
In contrast to what little is known about dinosaur migration movements, temporal migration is something that we observe in our modern birds. Today’s birds have breeding and wintering grounds. Breeding grounds are used when there is a surplus of resources for parents to rear young. Birds will then migrate south to wintering grounds when temperatures are starting to decline in the north.
One exceptional example of a migrating bird is the Swainson’s Hawk. Swainson’s Hawks, Buteo swainsoni, are found in North America during their breeding season where they will consume mostly small mammals. They will fly down to Argentina for their wintering grounds and live off a high insect-content diet. According to The Cornell Lab of Ornithology on Birds of North America, this can mean a round-trip of over 20,000 km, or over 12,000 miles. They can fly in groups, known as kettles, as large as 5,000-10,000 individuals at a time. Check out this short video by Native Birding Columbia of Swainson’s Hawk migration.
Migration can be made difficult for these birds when resources are low and they cannot adequately store fat reserves. Furthermore, the use of insecticide eliminates a large part of their insect diet when migrating to their wintering grounds.
There is not enough information to suggest that the migratory behaviors we see today were inherited from dinosaur ancestors or a trait evolved to survive seasonal conditions. We can agree that migration is test of great endurance and a sight to behold. You can observe magnificent migratory birds do these long migrations through your city every year.
One way you can meet a migratory bird is by visiting Pandora. Pandora, a Swainson’s Hawk, is an animal ambassador at The Urban Interface. Pandora is non-releasable due to a genetic deformity in the feathers of her right wing. Without their ability to fly, Swainson’s Hawks cannot hunt or migrate. Pandora serves as a representative of her species, by coming to classrooms, libraries, etc to help people reconnect to the nature around them.