Banding One Millions Birds

A Gambel's White-crowned Sparrow (Zonotrichia leucophrys gambelii) and an Eastern White-crowned Sparrow (Z. l. leucophrys).

Photo: Long Point Bird Observatory

Here is a recent article I wrote for BirdWatch Canada, a publication of Bird Studies Canada. This spring, Long Point Bird Observatory, for which I am the Program Coordinator, banded its one millionth bird, an milestone that no other Western Hemisphere bird observatory has yet reached. This article was part of a lead up to that event.

The False Allure of Garlic Mustard

The West Virginia White (Pieris virginiensis) is highly localized in Ontario. This one is nectaring on a non-native mustard. The presence of non-native mustards is partly responsible for the decline of the this woodland butterfly across much of its range.

Photo: Randy L. Emmitt (Wikimedia Commons)

Eastern Onatrio's Frontenac Arch is home to a wide variety of species at risk, including an unassuming woodland butterfly, the West Virginia White (Pieris virginiensis). It's a butterfly that's notable for a number of reasons: it's truly sylvatic, whereas almost all other Ontario butterflies are found in open habitats; it's restricted to only a handful locations in the province, and it has apparently disappeared from many of those sites in recent years; and perhaps most importantly, it has a taste for mustards (family Brassicaceae). It's a combination of all three of these things that has earned the West Virginia White the designation of a species of special concern in Ontario.

I have fond memories of living among West Virginia Whites, which I could find flying in May only a short bike ride away from my cabin on Opinicon Lake. My favourite West Virginia White colony, was found under a forest canopy composed of some thirty species of trees, where salamanders seemed to reside under every fallen log, and spring wildflowers bloomed in ridiculous profusion. Among the abundant wildflowers were two toothworts: Cut-leaved (Cardamine concatenata) and  Two-leaved (Cardamine diphylla), and it was upon these forest floor mustards that my West Virginia Whites fed. It's been several years since I last had the opportunity to visit my old colony, but I wonder with genuine concern how those rare butterflies are fairing.

In the past, the most pressing threat to West Virginia White populations throughout Ontario would have been loss or fragmentation of the mature forest habitat they and the toothworts require. Happily, my colony was safe from any kind of forestry, tucked away as it was on a large swath of protected land. The there was something else to worry about back then, in those heady days with my butterfly colony, and it's a worry that persists today: the insidious Garlic Mustard (Alliaria petiolata).

Garlic Mustard was intentionally introduced to North American from Europe as an edible herb during the mid 1800's. It has since expanded across the Great Lakes region and throughout much of the northeastern United States. Once established, it spreads like wildfire, choking out native vegetation and turning large areas of forest understory into Garlic Mustard monocultures. It's a terribly invasive species, more deserving of the appellation "weed" than almost any other woodland plant.

Just like the toothworts, Garlic Mustard is a member of the family Brassicaceae, the mustards. The mustard family includes such human favorites such as Broccoli, Cabbage and Cauliflower (Brassica oleracea), Turnip (Brassica rapa), Canola (Brassica napus), Common Radish (Raphanus sativus) and Horseradish (Armoracia rusticana). Many of these garden species are popular foodplants for introduced Cabbage White (Pieris rapae) caterpillars, but for West Virginia Whites the options are fewer because not many mustards grow in its dark forest habitat. The toothworts do and, unfortunately, so does Garlic Mustard. Indeed, I've spent more time than I care to recall pulling up Garlic Mustard in my woodlot. It's an annual chore, but it works to keep the forest floor more or less free of the nefarious weed. I fear however, that no one has been pulling Garlic Mustard at the old colony I used to visit years ago, and that may be cause for concern.

Garlic Mustard can out-compete the native toothworts for sunlight and soil nutrients, effectively eliminating them from the forest floor, leaving West Virginia Whites without their native foodplant. Interestingly, the butterflies will switch to using Garlic Mustard as a foodplant in the absence of toothworts, and may even prefer Garlic Mustard over toothworts. At first glance it seems like a fair trade off: replace one mustard with another and carry on. I mean, wouldn't stand to reason that the spread of Garlic Mustard would lead to a flourishing of West Virginia Whites, just as the planting of Crown Vetch (Securigera varia) along roadsides throughout southern Ontario has led to a drastic range expansion of Wild Indigo Duskywings (Erynnis baptisiae). In the case of the duskywing, which was once restricted to a small portion of southern Ontario, it has recently taken up the non-native vetch as a new larval foodplant and expanding its range as a consequence of this new widely available resource. In western North America, the naturalization of non-native Fennel (Foeniculum vulgare) has allowed Anise Swallowtails (Papilio zelicaon) to produce produce two flights every year, when previously it produced only one. This shift from unvoltinism to multivoltinism in the swallowtail was assisted by the tremendous abundance of Fennel which augmented the supply of natural carrot family (Apiaceae) foodplants. In strong contrast, however, the abundance of Garlic Mustard has actually had a negative effect on West Virginia Whites.

Lab experiments and field observations in the American portion of the West Virginia White's range have shown that caterpillars which feed on Garlic Mustard never reach maturity, usually dying after several days. Garlic Mustard, though attractive as an ovipositing site to adult females, is actually a death sentence to any caterpillar unlucky enough to hatch there. The Garlic Mustard's chemical defenses and a suite of growth inhibitors in the plants kill all caterpillars by the time they reach their second instar. Or at least that's the case in most populations. In at least one Massachusetts  population, however, caterpillars are able to survive until the pupal stage by feeding on Garlic Mustard alone. Though the caterpillars took longer to pupate and were a third smaller than caterpillars that grew up on toothworts, they did survive. Perhaps other populations of West Virginia Whites may also be able to adapt to use Garlic Mustard.

There may be some hope for West Virginia Whites if other population can shift to using Garlic Mustard successfully. But that's not likely to happen soon enough to stop the decline of this species all across its range. Evolution is a long and often risky road, after all. It seems that combating Garlic Mustard where it has become established and keeping it from spreading into pristine woodlands in the first place is the best defense we can give West Virginia Whites. So I keep pulling and spraying Garlic Mustard in my woods and I keep hoping that the old colony of mine is still flourishing under those big trees half a province away, and not just in my memories.

Understanding Molt: A Bander's Perspective

The broad, round-tipped, thick flight feathers, sharply contrasting black and white primaries and alula, nearly unifromly white secondaries, and pure white primary coverts all indicate this Snow Bunting (Plectrophenax nivalis) is a male in definitive basic plumage, meaning that it hatched in at least 2014 (this bird was captured in January 2016). Molts and plumages are among the most important features used for aging birds during the banding process.

Photo: Mark Conboy

This primer on molt in birds is read by all new volunteers and staff at Long Point Bird Observatory (LPBO). This is the most basic level of understanding that banders are expected to have before they can begin work in the banding lab. This primer assumes that the reader has at least a basic understanding of feather terminology (i.e., what are the greater coverts versus median coverts).

In bird banding, a comprehensive understanding of the strategies, timings, and mechanics of molt is necessary for aging birds with accuracy and precision. Molt is a cyclic pattern of feather replacement, and is highly variable between species, and exceptions occur to almost all of the "rules" that follow, but in general terms:

• Every species at LPBO molts all of its feathers at least once a year, usually after the breeding season.
• Some species have an additional annual molt before the breeding season.
• In most species, young birds molt differently than adults. For example, some species have two molts during their first 12 months of life, but only have a single molt every 12 month after that for the rest of their lives.

Note: The term molt is best reserved only for feather replacement that is part of a cyclic and predicable process, so that the growth of new feathers to replace randomly lost or damaged ones is not considered to be a true molt, but should instead be referred to as adventitious feather replacement.

In general, molt is usually symmetrical, meaning, for example, that a feather actively molting on the left wing is simultaneously molting on the right wing. Similarly, if the outermost tail feather is actively molting on the left side of the tail, the outermost tail feather on the right side should be molting simultaneously.

Molt usually occurs in a predictable sequence and that sequence is reflected in the numbering system we apply to the wing and tail feathers. All of the wing’s flight feathers and the tail feathers are numbered in the order which they typically molt.

Wing and tail feather terminology and numbering.

Illustration: Adapted from the North American Banders' Study Guide (North American Banding Council)

In most species, the primary feathers molt from the innermost to the outermost, and the secondary feathers molt from the outermost to the innermost. The tail feathers, properly called rectrices, molt from the innermost to the outermost.

In order to age birds you will need to know what patterns of molt each species uses. Read the molt section in Pyle for each species as you encounter them. Contained within the molt section is almost all of the information you need to age a bird. Pyle tells you what kind of molt(s) each species undergoes and when it occurs. Pyle also notes exceptional (eccentric) kinds of molts that don't fit the general patterns discussed below.

There are three types of molts that you will regularly encounter at LPBO: preformative, prebasic and prealternate. These types of molts can occur in several different arrangements or molt strategies. The majority of LPBO birds follow two particular molt strategies:

1. Complex Basic Strategy

Natal Down

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Prejuvenal Molt à Juvenal/First Basic Plumage

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Preformative Molt à Formative Plumage

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Definitive Prebasic Molt à Definitive Basic Plumage

2. Complex Alternate Strategy

Natal Down

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Prejuvenal Molt à Juvenal/First Basic Plumage

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Preformative Molt à Formative Plumage

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First Prealternate Molt à First Alternate Plumage

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Definitive Prebasic Molt à Definitive Basic Plumage

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Definitive Prealternate Molt à Definitive Alternate Plumage

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Definitive Prebasic Molt à Definitive Basic Plumage

Note: There are two additional molt strategies that are rarely used by species encountered at LPBO, so won’t be addressed in detail here: Simple Basic Strategy and Simple Alternate Strategy.

Though these diagrams may seem nebulous, especially if the terminology is new to you, they will become more clear as we examine each molt and each plumage in turn, below. Fundamental to this, is understanding that molts preceed plumages and plumages only arise from molts. A bird cannot change plumages without molting!

Note: Molts are named with the prefix “pre”; so that the molt which leads to a bird’s juvenal plumage is called the prejuvenal molt. There are other molt and plumage terminology systems in use, but the one presented here is the best and is the one in most widespread use among banders today.

We will examine all of the molts and plumages and outline, briefly, how they can be used to determine the age of a bird, beginning with natal down. Natal down is the first kind of feather that nestlings grow. Some species hatch fully covered in down (precocial), others hatch naked and subsequently grow down (altricial). The development of natal down is not considered a true molt. True molts actually begin with the next stage of feather growth.

The prejuvenal molt occurs in the nest. It leads to the development of juvenal plumage. The prejuvenal molt is sometimes also referred to as the first prebasic molt and juvenal plumage is sometimes called first basic plumage. At LPBO we tend use the more intuitive terms prejuvenal molt and juvenal plumage. The prejuvenal molt is unusual in that all feathers are grown at the same time, thus it is a simultaneous molt. All subsequent molts in a bird's life are sequential molts, meaning feathers are replaced a few at a time, not all at once.

Juvenal plumage is grown in the nest. Its primary function is to make young birds mobile so they can leave the nest, reducing the risk of depredation and giving them the ability to follow their parents while they forage. Juvenal plumage is short-lived, lasting for only a few weeks in most LPBO species, before being replaced by formative plumage. Juvenal plumage, aside form usually looking very different from all subsequent plumages that a bird will have, has particular characteristics that make it distinctive. Understanding these characteristics is imperative to aging birds in non-juvenal plumages (i.e., formative, basic, alternate):

• Body feathers are whispy, with widely spaced barbs; they have the appearance of being low-quality feathers.
• Primary feathers are usually narrow with a somewhat pointed tip.
• Retrices are usually narrow and come to a noticeably pointed tip.
• Flight feathers are usually dull coloured, with limited or no coloured edging.
• Flight feathers and rectrices are usually thin, sometimes to the point of being translucent.
• Growth bars line up across the wing and tail feathers.
• Fault bars, when present, line up across the wing and tail feathers.

Recognizing the characteristics of juvenile feathers takes practice. In fact, all of these characteristics should be thought of in relative terms, so that juvenal feathers are more pointed than non-juvenal feathers. After handling many individuals of the same species you’ll begin to understand the relative differences between juvenal and non-juvenal feathers.

Note: Growth Bars are feather pigment bands that, when visible, can be useful for aging birds. Growth bars develop because daytime and nighttime metabolic processes take place at different rates in birds, so that pigment deposition is more concentrated during the day and less concentrated at night. In some species or individuals, growth bars can be difficult to see, but in other species or individuals they can be easily detected. Because the prejuvenal molt is simultaneous, juvenal plumage growth bars line up across the wing feathers and rectrices. Conversely, all other molts are sequential, so growth bars don't line up across the feathers that have grown during the preformative, definitive prebasic or prealternate molts. Growth bars in the rectrices need to be used with caution because it is possible for a bird in definitive basic plumage that accidentally lost its tail to adventitiously regrow those feathers simultaneously, in which case it may have growth bars similar to a bird in juvenal plumage. Fault bars are growth bars that developed during periods of stress, so that pigmentation is particularly weak. They are usually very obvious, but their occurrence is somewhat infrequent. In addition to being weakly pigmented, fault bars are also usually structurally weak, meaning they are prone to breaking, leaving the feathers looking unnaturally truncate. The same characteristics and cautions apply to fault bars as to normal growth bars.

Growth bars in Carolina Wrens (Thryothorus ludovicianus) and other wrens show up as dark bands on the wing feathers and rectrices. Growth bars are usually far less obvious in other birds, but the principle is the same. The top photo is of a bird in definitive basic plumage, showing dark growth bars slightly staggered on the wing feathers. The bottom photo is of a bird in formative plumage, showing dark growth bars that line up across the inner greater coverts and across the primaries and secondaries.

Photos: Marie-Anne Hudson (Piranga)

The preformative molt replaces the juvenal plumage with the formative plumage. The most important thing about the preformative molt is that it is typically a partial molt. That means most or all body feathers, but usually no primaries, secondaries, tertials or retrices are replaced (in some species a few tertials or the central rectrices may be replaced).

Note: Part 1 of Pyle doesn’t use the term preformative molt, but instead uses the term first basic molt. This volume was written before a new (and more accurate) terminology came into use. When Part 1 of Pyle says first prebasic molt, it really means preformative molt. When Part 1 of Pyle says first basic plumage, it really means formative plumage. You should attempt to always use the new terminology and not the terminology used in Part 1 of Pyle. Part 2 of Pyle, having been more recently published, uses the new terminology.

Formative plumage is roughly analogous to what most field guides call immature plumage. Understanding that formative plumage follows the partial preformative molt is crucial to aging LPBO birds! So, once again: typically, the preformative molt is partial, involving the replacement of only some juvenal plumage with formative plumage, while retaining other parts of the juvenal plumage. Here, the concept of molt limits becomes important. A molt limit is the contrast between different generations of feathers. In formative plumage a bird will show contrast between retained juvenal and replaced formative feathers. Detecting molt limts is the key to aging birds by plumage. Typically, molt limits occur in the wing feathers. In many LPBO species, juvenile primaries, secondaries, tertials and primary coverts are retained, while the greater, median and lesser coverts are replaced (fully or partly) by formative feathers. Thus there may be a visible molt limit between the retained juvenile feathers and replaced formative feathers in birds that have completed their preformative molt. Formative feathers are usually brighter in colour, rounder-tipped, broader, and thicker. In general, they look very much like definitive basic feathers (see below). When we detect a molt limit that's the result of a preformative molt, we know that the bird hatched in the most recent breeding season.

Myrtle Warbler (Setophaga coronata) in formative plumage. The primaries, secondaries, primary coverts and alula are retained juvenal feathers, while the greater and median coverts are replaced formative feathers. This molt limit, between the duller juvenal feathers and brighter formative feathers could only occur on a bird that hatched in the most recent breeding season.

Photo: Marcel Gahbauer (Piranga)

Note: When looking for molt limits, it is important to be aware of pseudolimits in some species. Pseudolimits are apparent contrasts between feathers, giving the impression of a true molt limit, but they are merely inherent differences between feathers of the same generation, thus are not indicative of a bird's age. Only a handful of LPBO species regularly have confusing pseudolimits, including many sparrows and Brown Thrasher (Toxostoma rufum).

Brown Thrasher (Toxostoma rufum) in definitive basic plumage. The apparent contrast between the inner and outer greater coverts is normal for Brown Thrashers in all plumages; it is a pseudolimit and is not useful for aging.

Photo: Peter Pyle (Piranga)

The definitive prebasic molt replaces formative plumage with definitive basic plumage. In contrast to the preformative molt, the definitive prebasic molt is almost always a complete molt in LPBO birds. Every single feather on a bird’s body is replaced during a complete molt: every body feather, every flight feather, and every rectrix. For LPBO birds, the definitive prebasic molt usually occurs on the breeding grounds, right after breeding is completed, though exceptions do occur. The reason the molt is called definitive is because it occurs every year of the bird’s life, except for its first year, when the preformative molt takes place at roughly the same time. The preformative molt occurs only once, replacing the juvenal plumage, while the definitive prebasic molt occurs every single year thereafter.

Myrtle Warbler (Setophaga coronata) in definitive basic plumage. All of the feathers of the wing are broad, round-tipped, and thick. There are no molt limits, meaning that this bird hatched not in the most recent breeding season, but at least in the season before that.

Photo: Marcel Gahbauer (Piranga)

Definitive basic plumage is roughly analogous to what field guides call adult plumage. It differs from formative plumage in that no juvenal plumage is mixed in with the basic feathers. When a bird is found to have only definitive basic plumage we know that it is one that hatched not in the most recent breeding season, but at least in the season before that. It is impossible to age most LPBO birds with any more precision than that because the definitive basic plumage occurs in birds that are one year old, two years old, three years old, etc; it is the same every year following the preformative molt. Definitive basic plumage has particular characteristics that make it distinctive from juvenal and formative plumages. Understanding these characteristics is imperative to aging birds:

• Body feathers are tight and crisp with dense barbs; they have a high-quality appearance.
• Primary feathers are usually broad and a fairly rounded at the tip.
• Retrices are usually broad and come to a noticeably truncate end.
• The feathers of the wing are usually colourful, usually with thick coloured edging.
• Flight feathers and rectrices are usually thick.
• Growth bars do not line up across the wing and tail feathers.
• Fault bars, rarely present, don't line up across the wing and tail feathers.

Like with juvenal feathers, recognizing the characteristics of definitive basic feathers takes practice, and should be thought of in relative terms, so that definitive basic feathers are less pointed than juvenal feathers, for example. After handling many individuals of the same species you’ll begin to understand the relative differences between definitive basic and juvenal feathers.

The complex alternate molt strategy has two additional types of molt that are not part of the complex basic strategy. These are called prealternate molts and they result in the development of alternate plumages, which are roughly analogous to the breeding plumages illustrated in field guides. Less than half of LPBO species have a prealternate molt and in all cases it's a partial or incomplete molt. Prealternate molts usually take place on the wintering grounds either in winter or early spring.

Note: In banding terminology there is an important distinction between partial and incomplete molts. As discussed earlier, partial molts include most or all body feathers, but usually no primaries, secondaries, tertials or retrices are replaced (in some cases a few tertials or the central rectrices may be replaced). By contrast, incomplete molts usually include the replacement of all body feathers as well as some primaries, secondaries, tertials and/or rectrices. Partial prealternate molts are far more common among LPBO species than are incomplete prealternate molts.

The first prealternate molt is partial (or in some cases incomplete) and results in the first alternate plumage. The first prealternate molt replaces some feathers of the formative plumage. The first prealternate molt usually is limited to feathers of the head as well as the greater, median and/or lesser coverts in many LPBO species. In other species, such as American Goldfinch (Spinus tristis), almost all of the body feathers will also be replaced, but such extensive molts are not the norm for LPBO species. Incomplete molts may also include some primaries, secondaries, tertials and/or rectrices. Birds in first alternate plumage may thus show molt limits between three generations of feathers in their wings (e.g., juvenal primaries, secondaries, tertials and primary coverts, formative outer greater coverts, and first alternate inner greater coverts, as seen in some Myrtle Warblers [Setophaga coronata]). When we detect molt limits that are the result of a first prealternate molt, we know that the bird hatched in the most recent breeding season.

Myrtle Warbler (Setophaga coronata) in first alternate plumage. The primaries, secondaries and primary coverts are retained juvenal feathers. The second outermost greater covert is a formative feather, while the rest of the greater coverts and median coverts are first alternate feathers. These molt limits, between three generations of feathers, duller juvenal feathers, a slightly brighter formative feather, and brightest first alternate feathers, could only occur on a bird that hatched in the most recent breeding season.

Photo: Marcel Gahbauer (Piranga)

Like the first prealternate molt, the definitive prealternate molt is partial (or in some cases incomplete); it results in the definitive alternate plumage and replaces some feathers of the definitive basic plumage. The definitive prealternate molt is usually also limited to feathers of the head as well as the greater, median and/or lesser coverts in many LPBO species. But there are cases when body feathers, primaries, secondaries, tertials and/or rectrices are replaced. Birds in definitive alternate plumage show molt limits between two generations of feathers in their wings (e.g., definitive basic primaries, secondaries, tertials, primary coverts and outer greater coverts, and definitive alternate inner greater coverts). When we detect molt limits that are the result of a definitive prealternate molt, we know that the bird hatched not in the most recent breeding season but at least in the season before that.

Myrtle Warbler (Setophaga coronata) in definitive alternate plumage. All of the feathers of the wing are broad, round-tipped, and thick. The primaries, secondaries and primary coverts are definitive basic feathers, while the greater coverts and median coverts are definitive alternate feathers. A molt limit of this kind means this bird hatched not in the most recent breeding season, but at least in the season before that.

Photo: Marie-Anne Hudson (Piranga)

Note: There is another type of molt that is rather rare among North American songbirds, which I haven't yet addressed: the presupplimental molt, which leads to the supplimental plumage. Presupplimental molts can vary widely between species. For example, one species may molt only wing feathers, while another species may molt only body feathers; thus, presupplimental molt is sort of a catch-all term which is applied to any molt, whether it be partial, incomplete or complete, that occurs in addition to the prejuvenal, preformative, prebasic and prealternate molts. Only two LPBO species are known to undergo presupplimental molts of any consequence: Northern Cardinal (Cardinalis cardinalis) and Indigo Bunting (Passerina cyanea). Refer to Pyle for details about aging these species.

When aging birds by molt, put all of the above information together to decide what age to give the bird:

1. Read the molt section in the species account in Pyle so you know what to look for at a given time of year.
2. Eliminate all plumages you are not likely to encounter at the time of year.
3. Open a wing and look at the primaries, secondaries, tertials, primary coverts and greater coverts in particular, for molt limits. Determine molt limits by comparing the shape, colour, thickness and amount of wear between feathers.
4. If molt limits are present, determine if they are the result of a preformative molt or a prealternate molt. If molt limits are not present determine if the feathers are uniformly juvenal or non-juvenal.
5. Open the tail and look for molt limits. Determine molt limits by comparing the shape, colour, thickness and amount of wear between feathers. Pay particular attention to the central and outer rectrices.
6. If molt limits are present, determine if they are the result of a preformative molt or a prealternate molt. If molt limits are not present determine if the feathers are uniformly juvenal or non-juvenal.
7. Look at the body feathers. Determine if the body feathers are juvenal or non-juvenal. Use the plumage criteria given in Pyle to see if additional clues about age can be found in the colours of body, wing feathers and rectrices.
8. Look at other characteristics such as colour of the eyes, orbital skin, legs, beak and/or mouth lining. Determine if the bird has a gape, is in breeding condition, and/or if the skull is completely ossified (look for these last three criteria at the appropriate time of year).
9. Come to a final decision about the bird's age based on a combination of criteria.

If there is conflicting evidence for age, it may be necessary to make a decision based on the strength of one criterion over another. In general, the most reliable plumage features (for a suitably experienced bander) are the wing feathers. Adventitious replacement or extreme wear of rectrices can result in confusion, so I prefer to use rectrics in combination with other plumage criteria, namely the wing feathers, when possible. Body feathers can be deceiving to inexperienced banders who expect males to always be brighter than females and visa versa - this is not necessarily the case, especially with the warblers! The use of non-plumage characteristics should not be overlooked, especially skull ossification, which with practice, can be the most accurate way to determine a bird's age.

There are plenty of additional resources about molt:

Piranga (NatureInstruct)

North American Banders' Study Guide (North American Banding Council)

The Variety of Molt Strategies (Steve N.G. Howell)

Finding Order Amid the Chaos (Steve N.G. Howell)

Aging North American Landbirds by Molt Limits and Plumage Criteria (Dan Froehlich)

As you read through these documents, and as you begin to work in LPBO's banding lab, you will see that aging birds by molt is far more nuanced and fraught with exceptions than I've presented here. This makes banding a source of perpetual learning and challenge, something that any serious bander will embrace, rather than dismay.

Designer Forests

Pawpaw (Asimina triloba) produce the largest fruit of any native North American tree and were probably widely planted and cultivated by first nations people.

Illustration: Mark Catsby

I live minutes away from one of the most biologically diverse patches of old growth forest remaining in Canada. It's a green paradise of endangered Tulip Trees (Liriodendron tulipifera) and imperiled Butternuts (Juglans cinerea), massive American Beeches (Fagus grandifolia), impressive Basswoods (Tilia americana), generous Black Cherries (Prunus serotina), large Large-toothed Aspens (Populus grandidentata), ancient Sugar Maples (Acer saccharum), giant Black Maples (Acer nigrum), sky-high Northern Red Oaks (Quercus rubra), jumbo Eastern Black Oaks (Quercus nigra), broad Common White Oaks (Quercus alba), shaggy Shagbark Hickories (Carya ovata), bitter Bitternut Hickories (Carya cordiformis), stately Black Walnuts (Juglans nigra), substantial White Ashes (Fraxinus americana), towering Yellow Birches (Betula alleghaniensis), shady Eastern Hemlocks (Tsuga canadensis) and wind-sculpted Eastern White Pines (Pinus strobus). Tangled River Grape (Vitis riparia) vines drape over limbs high above the forest floor, while tenacious Poison Ivy (Toxicodendron radicans) and tendrilous Virginia Creeper (Parthenocissus quinquefolia) climb up trunks. Diminutive American Chestnuts (Castenea dentata), fragrant Sassafras (Sassafras albidum), strong Blue-Beeches (Carpinus caroliniana), superstrong Ironwoods (Ostrya virginiana), beautiful Eastern Flowering Dogwoods (Cornus florida), oriental Pagoda Dogwoods (Cornus alternifolia), spreading Witch-Hazel (Hamamelis virginiana), spicy Spicebush (Lindera benzoin), and rare Wahoo (Euonymus atropurpurea) fill out the understory. Slender Black Gums (Nyssa sylvatica), regal Swamp White Oaks (Quercus bicolor), girthy Bur Oaks (Quercus macrocarpa), huge Red Maples (Acer rubrum), stupendous Silver Maples (Acer saccharinum), hefty White Elms (Ulmus americana), modest Slippery Elms (Ulmus rubra) and robust American Sycamores (Platanus occidentalis) ring salamander breeding ponds. Quiet and solitude pervade. In this place, it's tempting to think that this remnant forest is a pristine urwelt, untouched since glacial times. But that's simply not the case; humans have been influencing and impacting the forests in one way or another since time immemorial, including this one.

Since the arrival of Europeans in the Americas, forests have suffered tremendously. In my own patch of forest I see evidence of overharvesting of "medicinal" plants, namely American Ginsing (Panax quinquefolius); recreational vehicle damage; overgrazing by White-tailed Deer (Odocoileus virginianus) caused by poor management practices; the historical overhunting of fur and game animals which has left the woods impoverished of Fisher (Martes pennanti) and Elk (Cervus canadensis) and a host of other species; fragmentation by roads; increased incidences of Brown-headed Cowbird (Molothrus ater) parasitism on nesting birds because of reduced forest area; artificial drainage ditches; sterile conifer plantations; dozens of devastating introduced species like Chestnut Blight (Cryphonectria parasitica), Emerald Ash Borer (Agrilus planipennis) and Garlic Mustard (Alliaria petiolata); forest fire suppression; and the extirpation of top predators like Grey Wolf (Canis lupus). Other forests are impacted still further by industrial and selective forestry, clearing for agriculture, overgrazing by domestic livestock and fragmentation by pipelines, power transmission lines and seismic lines. Most of these impacts would be considered European in origin, perhaps with the exception of clearing land for agriculture. But first nation, especially along the St. Lawrence River and around the Great Lakes, were influencing and impacting forests, sometimes in extreme ways, long before the arrival of European explorers and settlers.

A farmstead carved out of Carolinian old growth near Chatham, Ontario, circa 1838.

Painting: John Philip Bainbrigge

The "untouched" forests that Europeans encountered in the Great Lakes basin were in many cases actually more like carefully designed landscapes, and not deep dark wildernesses. First nations people cleared forests for agriculture, sometimes on impressively grand scales, using fire and by girdling large trees. The fields were then planted up with Corn (Zea mays), beans, squash, tobacco and other medicinal and edible plants. After a decade or so, as local resources such as firewood, game animals and soil quality diminished, settlements were relocated, and fields were burned and left to regrow under natural succession. Where forests were left intact, controlled burns, usually in the form of modest ground fires, were used to clear forest understory of thick shrubs and forbs, promoting the growth of grasses and other forage favourable to game animals. Managing habitat with fire may have imperative to maintaining sustainable game populations around settlements since hunting pressure would have been intense. The legacy of these impacts is difficult to detect in forests today without diving into the pollen or charcoal records of a forest. There is another way, however, that first nations historically influenced forest ecology: sylvaculture of fruit- and nut-bearing trees; in some cases, we can still see evidence of that on the landscape today.

Doubtless, sylvacultural techniques would have differed culturally and geographically, but in general it seems to have included both the management of existing forests to promote the growth of productive old trees, and the planting of new trees in orchards. It was chiefly centered around settlements, where foods could be easily harvested and protected against pests and, no doubt, other humans. Pawpaw (Asimina triloba), oaks, Shagbark Hickory, Shellbark Hickory (Carya laciniosa), Pecan (Carya illinoinensis), American Chestnut, Allegheny Chinquapin (Castanea pumila), hazels, Black Walnut, Butternut, and American Beech were all utilized as food, and may all have been part of sylvacultural practices throughout eastern North America. The reality is, we don't know much about  historical first nations sylviculture, but what evidence we do have comes mainly from studies of witness tree records in the United States. Witness trees were trees marked and noted by surveyors as they laid out plots of land. In theory, witness trees should be representative of the relative abundance of species that were present when surveyors moved through a region, usually sometime in the 1700's and 1800's. Surveyors would have marked whatever tree was closest to corners of the lots they were mapping, so trees were essentially selected randomly (though some bias for selecting trees of certain size or species may have existed). Thanks to this historic record, ecologists have been able to show that a disproportionate number of witness trees around known former first nations settlements are nut-bearing trees.

First nations people may have reduced competition around nut-bearing trees by girdling or otherwise removing adjacent competitors. They also planted trees around settlements, sometimes in large orchards, if historical accounts are accurate. In the course of establishing orchards, trees were sometimes moved well beyond their normal range. I suspect that the few Shellbark Hickories near Long Point, Ontario, may have been moved there (as nuts) by first nations people; the massive nuts of Shagbark Hickory are not likely to have been transported by wildlife over such a long distance from the next nearest populations: 135 km away on the Niagara Peninsula and 200 km away in Essex County. A similarly disjunct population of Pawpaws, again near Long Point, may have been established in the same way. Pawpaw produces the largest fruit of any native tree in North American and were certainly utilized by first nations south of the Great Lakes, so would have been a likely candidate for human-facilitated range expansion. In my childhood haunts of eastern Ontario, there is an isolated population of Bear Oak (Quercus ilicifolia), 200 km distant from the next nearest population in New York State, which is itself disjunct from the species' main range by a similar distance. Was this species brought to eastern Ontario by first nations people? Bear Oak isn't known to have been a particularly important food source, compared to Common White Oak for example, but Bear Oak acorns may have been accidentally transported along with other oaks and either discarded to grow feral or intentionally planted.

I would say that not enough consideration has been given to the influence of first nations on the abundance and distribution of fruit- and nut-bearing trees in North America. Though quantitative evidence is limited, it stands to reason that since other cultures all over the world have been moving useful and valuable plants around the globe for millennia, native Americans would have done the same. Certainly, other first nations' practices such as the widespread use of fire to modify landscapes, has been well documented. The historical legacy of fire use is now being considered in such a way as to cause us to redefine what we mean by untouched wilderness. Very few places on Earth are true wildernesses, truly untouched. Rather, almost everywhere that can support a viable ecosystem has been home to humans at one time or another, and humans, no matter how limited their population, or how conservation-oriented their society is, invariably impact and influence ecosystems in measurable ways. It's time to start looking at humans, both historic and contemporary, as part of forest ecology, not a separate and unnatural or external influence. Only once the human dimension is considered, can we hope to have a complete historic view of forests, and a more holistic approach to addressing modern day conservation concerns.

Lake Erie's Hidden Hydrocarbons

Beneath Lake Erie is a wealth of oil and natural gas, giving rise to an industry that many local people don't realize exists in their own backyards.

Photo: Mark Conboy

I came to live on Lake Erie a year and half ago. After a term as an environmental consultant working on various oil and gas developments in Alberta, I decided that an industrial job and big city life weren't ideal, so I said goodbye to the boreal forest, the Rocky Mountains, the great spreading plains, and moved east, far from the oil and gas heartland. But I was very soon to realize that Lake Erie, was in fact an oil and gas hub all its own.

Now, this wasn't a total surprise, but it was something I hadn't really considered. I knew, of course, that Canada's first hydrocarbon company had been established to make asphalt from near-surface tar deposits at Petrolia, Ontario. By 1858, the first true oil wells in all of North America were dug in southern Ontario near the town of Oil Springs (it wasn't until the following year that the American oil crazy took off when Edwin Drake famously drilled into a pressured reservoir at Oil Creek, Pennsylvania). The sight of oil pumpjacks and natural gas well heads spread out across the countryside was nothing new to me either. But, I admittedly got a big surprise when I unfolded a nautical chart of Long Point Bay, and saw the maze of pipelines which crisscrossed the lake bed, connecting dozens of gas wells. It had never occurred to me, that there was an offshore hydrocarbon industry on the Great Lakes. Then again, why shouldn't there be? Offshore ocean oil and gas industries exist all over the world, and with oil and gas deposits to the north and south of Lake Erie, it should have been obvious.

But the offshore oil and gas industry on Lake Erie isn't obvious. There are no permanent oil platforms. Natural gas drilling rigs are modest-sized barges that only take a week or so to dig a well and bring it into production, so their presence on the lake is not all that intrusive. Well heads and pipelines lay on the bottom of the lake, completely out of sight, aside from the small white buoys that mark their presence. Indeed, many people who live on Lake Erie have no idea that an offshore oil and gas industry exists.

There are close to 500 natural gas wells (and far fewer oil wells) currently in operation on the Canadian side of Lake Erie, though several thousand have been drilled since production began in 1913. In fact, almost the entire offshore oil and gas industry is based on the Canadian side of the Great Lakes. The only state which currently allows offshore production is Michigan, but all of the wells under Lake Michigan are drilled from shore. In Ontario, oil is harvested from Lake Erie using the same kind of shore-based technique, called directional drilling. This involves drilling vertically to desired depth, then drilling horizontally under the lake bed, sometimes for many kilometres, through the oil-containing rock formation. Once a well is operational, the oil is pumped directly back to shore. In this way, the risk of an oil spill is kept to an absolute minimum. Typical drilling for natural gas uses another approach. In this case specialized barges drill vertically into the lake bed. Once the drilling is done, the well is capped and connected to shore via a pipeline. There are some 890 km of pipelines in operation under Lake Erie today. Some directional drilling may be employed for natural gas as well, but given the reduced environmental contamination risks of natural gas, most drilling can safely occur offshore. Most wells are expected to produce for 10-20 years.

Major oil and natural gas pipelines in Lake Erie.

Map: Offshore Magazine

Lake Erie oil and gas is extracted from Silurian aged rocks, 419-444 million years old. When these rocks formed, Ontario was a very different place. The province was located some 6000 kilometres south, at approximately the same latitude where Bolivia sits today. Though having the enviable geography of a tropical paradise, Silurian Ontario would have been amazingly devoid of terrestrial life, because it would still be another few hundred million years before land plants and animals became abundant. Silurian ocean life was plentiful however, with fish diversifying rapidly and microscopic marine algae providing the foundation for food webs, just as it does today. For at least part of the Silurian, southern Ontario was covered by a relatively shallow tropical sea. It was from this sea that Lake Erie's oil and gas deposits arose. Dead organic materials, in this case Silurian marine algae and animals which become buried under layers of sediment are transformed into oil over millions of years through exposure to phenomenally high temperatures and pressures. Over time, exposure to heat and pressure chemically alters the trapped organic material, turning it into oil. In effect, when we use Lake Erie oil for fuel we are essentially burning ancient algal blooms, with perhaps a smattering of fish, sea scorpions, crinoids, mollusks and brachiopods mixed in. Natural gas that is harvested from beneath Lake Erie was formed in the same way oil, but gas can also be formed through the anoxic decomposition of organic matter under much simpler conditions such as in a bog or swamp, and during digestion by animals. Even humans create their fair share of natural gas; natural gas is simply methane, after all.

The Silurian rocks which contain Lake Erie's oil and gas are buried between 100 and 1100 meters below the lake bottom. Two types of natural gas are produced: at the eastern end of the lake sandstones and shales produce sweet gas, or natural gas that doesn't contain poisonous foul-smelling hydrogen sulfide. In the western half of the lake a series of ancient patch reefs, 10-40 metres thick produce sour gas, natural gas which does contain hydrogen sulfide. It's not uncommon for people to picture reservoirs of oil or gas as underground lakes. But that's not the way it is at all, in fact, the oil and gas are within the rocks themselves, filling tiny pores. The sandstones and shales, which are made of compacted and lithified Silurian sand and mud, respectively, are full of pores and those pores are full or oil and gas. The oil and gas didn't form inside those pores, but migrated there from their over long periods of time from its original location. Just as coffee percolates through a filter, oil and gas percolate their way through porous rock formations, some escaping to the surface, some getting trapped under impermeable layers of rock building up in large enough quantities for us to extract it economically. The formation of oil and gas deposits is a surprisingly dynamic process, only it takes place over such extraordinary timescales that it seems static from the typical human perspective. 

Compared to Alberta, Ontario's oil and gas industry is tiny. Virtually all of the production from Lake Erie's oil and gas fields is used in Ontario, but that only amounts to 1% of the province's annual oil consumption and 2% of annual gas consumption. Small potatoes. And thank goodness for that. Because, no matter how carefully an industry is regulated and no matter how much effort is made to reduce the risk of environmentally damaging oil spills, accidents do happen and when they happen in an offshore environment they can devastate ecosystems and be all but impossible to clean up. Spills and leaks seem to be relatively uncommon but they do occur in Lake Erie from time to time. Coming up with exact numbers for recent years isn't easy, but there are always a couple of small incidents annually.

Beyond the problem of oil spills and gas leaks, sedimentation, primarily from drilling waste, is another potential environmental concern. When wells are drilled, tailings in the form of sand, mud, rock particles and drilling fluids are released into the lake, where they can cause localized sedimentation. Whether this is a major problem for wildlife is unclear, but given that less than one hundred new wells are dug in the average year on Lake Erie, it probably is not. Compared to the uncounted tonnes of sand that is carried around the lake naturally by winds, currents and erosion, the harm caused by drilling sediment must surely be negligible, or at least very localized. That being said, drilling fluids do contain chemicals that are known to be harmful to humans, and unfortunately they are released (at least in some cases) directly into the lake; why exactly this is allowed and what health consequences may result is unclear.

Although Alberta (and to a lesser extent British Columbia and Saskatchewan) is the focus of Canada's oil and gas industry, southern Ontario is its birthplace. Lake Erie's small but sustained production has, for better or worse, kept the industry alive in Ontario for more than a century, even if it is relatively unknown.