Where Did All These Things Come From?!

This is a common phrase uttered when people view a concentration of snow geese during migration.

“Light geese” collectively refers to snow, blue (Anser caerulescens) and Ross’ (Anser rossii) geese, a group of medium to small geese that breed in the Arctic and winter from central Illinois south to the Gulf of Mexico. Snows and blues are the same species, interbreed, and may have young representing both color phases in the same brood. Ross’ geese are smaller than snows, almost always white and have a shorter bill with “caruncles” or warty bumps around the base. Both species are long-lived, able to reach 20 years in age, and do not begin breeding until after their second year of age.

Another common expression is: “I don’t remember these things being around here when I was a kid.” That’s because they weren’t! The continental population and range have shifted substantially in the last 40 years.

Why The Range Shift?

To answer that we need to take a closer look at snow goose ecology. Historically, populations hovered around 750,000 to 1 million individuals. The birds left their arctic breeding grounds in September stopping in the U.S. and Canadian prairies where they fed on grasses, roots and seeds of prairie and wetland plants. Winters were spent in the Gulf coast region where they primarily fed on the roots and shoots of various coastal marsh grasses. Snow geese’s short stubby bills are well suited to feeding by “grubbing” or ripping short vegetation out of the ground, getting the nutritious roots and below-ground shoots, not just the above ground leaves and stems. Spring migration reversed course, targeting similar food sources in similar habitats, which may have already been depleted during fall migration.

Because of the narrow window to breed in short arctic summers, snow geese arrive as soon as snow and ice recede enough to begin nesting before foods are available and geese must build sufficient nutrient reserves during migration to lay eggs and incubate their clutch. There is nothing to eat until near the end of incubation or as goslings start to hatch.

Snow geese aren’t just trying to survive migration, but to build the reserves they are going to need for reproduction in a few short weeks. They have cold weather to contend with, a marathon flight to the arctic, perhaps waiting a few days for snow to melt, then laying and incubation. Historically, many birds could not acquire enough nutrients to breed successfully, or to survive incubation. Those in poor condition would forgo laying a clutch of eggs, while others perished on the nest. Only the strongest and fittest survived and reproduced, holding the population steady at a relatively low level for decades, or even longer.

What Changed?

Food! With the advancement of modern agriculture across the U.S. and Canada, food became more abundant throughout migration and winter. Instead of subsisting on roots, shoots and seeds, light geese began thriving on waste grain left in fields. Common foods ranged from rice and soybeans in the wintering areas, to wheat and corn in the mid-latitudes, to rye, barley and peas in the northern prairies. Suddenly, instead of only a handful of birds being in sufficient body condition, that is, sufficient stored fat, calcium and protein, to breed, nearly all of them were. The population exploded, increasing drastically in a few short decades.

Great! Right?

Sort of…for a while. We like to see (most) bird species thrive, to a point. With the population jumping from around one million in the 1980s to 10 million in the mid-1990s, did this constitute too many? How do we define too many? What is the problem?

Until the 1970s we really didn’t know much about the breeding ecology of these birds. We knew they went north, and some early investigations indicated they bred in large colonies across the arctic landscape. Research outposts were established, and biologists began studying them annually. One effort looked at the impacts on Arctic vegetation. Exclosures were established to keep geese out of monitoring plots within breeding colonies, while ‘open’ plots provided a measurable comparison of feeding impacts. Through time, it became apparent the new, much larger, population was having a major impact on fragile vegetation communities. Remember the feeding behavior, grubbing? 10,000 geese grubbing in a colony didn’t denude the land, and the vegetation could mostly recover each year. 100,000 geese in a colony began to show impacts that appeared to last indefinitely. And some colonies expanded well beyond 100,000 individuals.

Just How Big was the Population?

Because breeding colonies were scattered across the vast tundra, they were hard to count. Similarly, the broad wintering distribution of light geese made them hard to account for during the Midwinter Survey taking place in January each year. These methods weren’t perfect, but they offered snapshots of the population and comparable trends. They showed the population had grown to perhaps as high as 3.5 million in just a decade or so.

But it seemed like there were more. Perhaps many more. Biologists also used banding data to generate population estimates. We know how many we “mark” (band). We know how many we “recapture” (harvest and report). From that we can estimate the total population. If 10 percent of marked birds are ‘recaptured,’ we are harvesting about 10 percent of our population. These estimates returned results around 20 million snow geese!

Biologists panicked. Dozens of species that breed exclusively in the arctic near snow goose colonies could be impacted by a permanently altered arctic ecosystem. A 1997 report titled Arctic Ecosystems in Peril detailed the population changes, impacts on the habitat, potential long-term effects and called for drastic and immediate action. Waterfowl managers agreed on the need for action, but there was debate about what to do. Recommendations ranged from capture and euthanasia to poisoning! These tactics may not make use of the birds, may be expensive and be publicly unpopular. Ideally, using hunters to address the situation was the most palatable possibility. Hunters valued the resource, would consume the meat, could take some pride in helping with an apparently dire situation, and there would likely be little cost to governments.

But how could hunter harvest increase enough to make that drastic of a difference? Hunting regulations were already as liberal as federal regulations, like the Migratory Bird Treaty Act, allowed on these geese. In 1999, Congress authorized the Light Goose Conservation Order, where “light geese” referred to the mid-continent population of snow and Ross’ geese. Greater snow geese in the Atlantic Flyway were added later as their numbers ballooned as well. This is not a ‘hunting season’ but a special provision, or ‘conservation order,’ of the Migratory Bird Treaty Act allowing for control measures and more liberal harvest regulations for species deemed harmful or overabundant. The goal was to decrease the continental population by one half in 10 years. Hunters responded immediately, pursuing these geese more intensively using a variety of methods. Marketing for guides and outfitters and various articles showed pictures of skies full of geese, fields full of decoys and piles of harvested birds in magazines, across the internet and, more recently, on social media. Hunters wanted to take part and calls to “Save the Tundra!” circulated widely.

Did it Work?

Growth rates slowed but did not immediately reverse. That is, the increase slowed, but was still increasing. Then nature kicked in. The Arctic is a brutal landscape, even in summer. Over the course of a few years, cold spring rains or snowstorms occurred just after hatch. Because of the incredibly short arctic summer, nearly all geese in a colony, or even across the arctic, nest and hatch within a few days of each other. These weather events take an enormous toll on young goslings that haven’t developed adult feathers for insulation and water proofing and resulted in almost zero production in some major colonies in multiple years.

Currently, the population is reduced, but not to the goal of the Arctic Ecosystems in Peril report. There is debate among population managers whether the goal is realistic, or still necessary. The arctic habitats that spurred so much concern are still degraded in places, but continued monitoring shows signs of recovery after ten years or so of reduced feeding pressure. It’s important to remember the arctic is huge, and suitable breeding habitat may exist for geese and other species outside of traditional colonies. The Light Goose Conservation Order is still in effect with steady participation from hunters. However, harvest is heavily skewed towards juveniles, which doesn’t reduce the breeding population, and total harvest falls during poor production years. The snow goose story is a unique one, and offers important lessons in ecology, population and harvest management, and bringing together biologists, legislators, U.S. and Canadian officials, and hunters to tackle a complex problem.

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Randy Smith is the Illinois River Project Director for The Nature Conservancy based at The Emiquon Preserve where he focuses on wetland and big river conservation and management. He’s previously held positions with Illinois Department of Natural Resources and Illinois Natural History Survey in roles focused on wetlands and waterfowl.