book review

Terns, by David Cabot and Ian Nisbet

I remember the first time that I saw a Tern in Southern Ontario, and believed that I was seeing an especially rare sighting. In my head at the time (this was almost ten years ago) Terns were oceanic birds that migrated huge distances across the waves, and were either in the middle of the Arctic Ocean, or amid stormy Southern seas. This idea of Tern distribution and migration was based on the only Tern species that I knew: the Arctic Tern (Sterna paradisaea) and even then only loosely. The Tern I observed flying and diving for fish in Waterford, Ontario was most likely not an Arctic Tern, but rather a Common Tern (Sterna hirundo). Since that perspective-changing observation, I have been looking forward to learning more about these beautiful birds. Thanks to this excellent book by David Cabot and Ian Nisbet, I now have a much greater grasp on Tern biology, ecology, and life history.

Terns is part of a long-running natural history series produced in the UK called The New Naturalist Library. These books are beautiful to look at, both outside and inside and I love having some of this series displayed on my bookshelf. The subtitle of the series is “A Survey of British Natural History” and I will admit to being originally concerned that the content of the books would be not very relevant to a naturalist on the other side of the Atlantic Ocean. For this book in particular, that fear was unfounded. While the focus is undoubtedly British and sometimes very explicitly so, the coverage of this book is extremely valuable to understanding Terns across the world.

The Collins New Naturalist Books are beautiful together on a bookshelf. This is my collection so far.

The book begins with a chapter titled “Terns of the World”, which gives a brief overview of what the authors consider the “true terns” which includes 39 species, and excludes the noddies (genera Anous and Gygis). This brings me to my first complaint in what I consider an excellent book: the use of scientific names (or lack of use). This first chapter is the only chapter to regularly use scientific names when mentioning related terns (ie. genera) or species. Some might find that scientific names break the flow of a book, and I’m sure that’s why it’s written without them later on (for the most part) but I find it incredibly helpful to have the scientific names referenced more often than once at the beginning of a book. I like to remember scientific names of species, it makes finding information about the species a lot easier, and it can even tell you things right in the name itself: members of a Genus are more closely related to each other than members of a different Genus. To use some Tern species as examples: the Arctic Tern (Sterna paradisaea) is more closely related to the Common (Sterna hirundo) and Roseate (Sterna dougallii) Terns (note the same Genus for all three species) than all three are to the Sandwich Tern (Thalasseus sandvicensis) (different Genus). I think the lack of scientific names in most chapters seems out of place given that the text is fairly in-depth and scientific. Even if they didn’t want the flow thrown off for most of the text, I would have liked it if they included the scientific names for the species that were the focused subject of later chapters (see below) even just in the chapter titles for easy reference. In any case, this first chapter does a great job of introducing the terns as a group, offering overviews of the various genera and setting the stage for the following chapters.

The next three chapters continue the theme of giving information on Terns as a whole, and not just the species that are common in Britain and Ireland. They are titled “Food and Foraging”, “Breeding Biology”, and “Migration”. All were full of fascinating information and surprises. “Food and Foraging” described the various ways that Terns find and capture prey (all Terns are predators of mostly aquatic prey except for the Gull-billed Tern (Gelochelidon nilotica) which feeds on mostly terrestrial prey). The chapter conveyed well the foraging strategies of Terns from their perspective, demonstrating how difficult it is for birds to find and catch fish out of water that is often deep. Something I never really considered before is how Terns depend on fish being closer to the surface than fish normally swim. There are various factors that bring fish within the top portion of the water, and thus within reach of Terns (and other aerial predators). One is currents forcing fish to move over shallower sections of a lake or ocean such as sandbars or reefs. But the authors state: “The most widespread factor making prey fish come towards the surface, however, is predatory fish chasing them from below.” Because of this, many Terns follow predatory fish in order to reap the rewards from their attacks on prey fish. This sort of dependence is the sort of behaviour and ecology that I find so fascinating: Terns and Tuna, two utterly different organisms in shape and lifestyle are connected through their use of common prey species. In this sort of way, all species are interconnected and it’s this sort of thing that ecology strives to document and understand. Through the use of photographs, illustrations, and excellent description Tern food acquisition is explored (including the always interesting kleptoparsitism, or food piracy).

This is the closest encounter I’ve ever had with a Tern, a Black Tern (Chlidonias niger) hovering near me in Long Point.

The following chapter, “Breeding Biology” describes the generalizations and variations on the ways Terns reproduce. Terns use impressive courtship displays both in the air and on the ground to attract and retain mates. I found the description of courtship-feeding (in which the male brings prey to the female) to be especially interesting, summarized nicely by the authors: “Thus, the function of courtship-feeding evolves gradually from advertising the male’s proficiency, through attracting a mate, establishing and cementing a relationship, to provisioning the female and providing the nutrition required for making the eggs.” Once the pair is established, both partners incubate the eggs, feed the chicks and guard them, though males are more likely to provision more often both the female and the chicks (probably because of the continuing courtship-feeding described above).

The final chapter in the broader overview section of the book is all about Migration. My vision of Arctic Terns being exotic oceanic birds crossing the globe is actually not entirely inaccurate. Some populations of Arctic Terns spend the northern summer breeding in the Arctic, and spend the northern winter in the Antarctic, literally crossing from the top of the world to the bottom. It’s mentioned that because of this incredible world-spanning migration: “These birds would experience more daylight in the course of a year than any other animal.” (p 91). Despite these amazing journeys that inspire appropriate awe and interest, we know very little about how Arctic Terns actually migrate, or even their migration routes in detail. This is true of other Terns as well, though the picture is slowly resolving as we gain better technology for tracking bird movements. This chapter explains the current state of tern migration knowledge well and mentions where we are still lacking information.

The chapter following the overview chapters detailed above brings the focus more directly onto Britain and Ireland, as it’s titled “History of Terns in Britain and Ireland”. The chapter delivers on its title, including excellent historical illustrations. Not only does the chapter describe the population changes of the different species of Terns in Britain and Ireland over time, but it mentions some of the reasons (when known) for such changes, as well as various human interactions with these species. Mentioned several times through this chapter is the egg collecting and the methods of scientific collecting in the past (shooting dozens of birds per colony with guns instead of cameras), which obviously had negative effects on tern populations.

The main portion of the book (almost half, if you don’t include the Appendices and References) is made up of five chapters each of which is devoted to a single species of Tern, the five species of Terns that breed in Britain and Ireland. These are: Little Tern (Sternula albifrons), Sandwich Tern (Thalasseus sandvicensis), Common Tern (Sterna hirundo), Roseate Tern (Sterna dougallii), and Arctic Tern (Sterna paradisaea).

These species-focused chapters are thorough and engaging, presenting a detailed account of breeding biology, habitat use, and behaviour. There are specific details included about the populations within the region of focus (the British Isles) such as historical population trends and distribution. Despite this regional focus, the descriptions of tern behaviour and biology is applicable across these species’ range. The Least Tern (Sternula antillarum) is closely related to the Little Tern, and has been spotted in Ontario. Common Terns are widely distributed, also occurring in Ontario. Arctic Terns sometimes occur in Ontario as well. So 2 of 5 species occur both in the British Isles and my own region, and another is very closely related and similar to a local species.

This photo demonstrates better the colouration of Black Terns though it is further away.

Following the species-chapters is a chapter on Conservation, full of case studies and the description of various effects on tern populations in the British Isles, as well as the efforts to alleviate the negative effects.

The final chapter was probably my least favourite, only because I don’t live in Britain or Ireland. Chapter 12: “Vagrants, Passage Migrants, and Occasional Breeders” is aimed very specifically at the British Isles Birder, describing the rare tern sightings within the region.

To round off the book, there are a few Appendices which were good supplementary material on Tern Research and Population monitoring.

Overall, Terns is an excellent book about the biology and behaviour of Terns with a distinct focus on the species that breed in the British Isles. But don’t let your locality deter you from checking out this book if you are interested in diving deep into the world of these fascinating seabirds.

For previous book reviews, see:

Flora of Middle-Earth

Pterosaurs, by Mark Witton

The Social Biology of Wasps

The Palaeoartist’s Handbook, by Mark Witton

Flies: The Natural History and Diversity of Diptera, by Stephen A. Marshall

mammals Species Profile

Big Brown Bat

Big Brown Bat (Eptesicus fuscus). Photo by Sherri and Brock Fenton, used with permission.

Last year, I observed 2 bat species while on a night hike with the Norfolk Field Naturalists (for more about this hike, go here). The 2 bat species I observed were Eastern Red Bats and Big Brown Bats. I’d like to explore their biology and natural history, specifically within Ontario. This first post will be focused on the Big Brown Bat and another will focus on the Eastern Red Bat. I will be pulling most of my information from The Natural History of Canadian Mammals (2012), by Donna Naughton, unless otherwise indicated.

Big Brown Bats (Eptesicus fuscus):

Meaning Behind the Name: Eptesicus is from Greek which means “I fly” and “house” because Big Brown Bats like to roost in houses, and the species name fuscus is Latin for “dusk” (Etymologia 2005).

Biology and Natural History:

At 13 cm long and with a wingspan of up to 39 cm, this is Ontario’s second largest bat (the largest being the Hoary Bat (Lasiurus cinereus), and is fairly common in southern Ontario. Their global range extends all the way south to South America, and at the northern end there are scattered reports from Alaska. With such a wide range, there are differences in their habits across it. For example, Big Brown Bats in Ontario hibernate through the winter in “caves, mines, and deep rock crevices, as well as heated buildings” (Naughton 2012), but in more southern regions with plentiful insect food throughout the winter, they are active year-round. The list above of hibernation sites are specific permanent locations bats will find to spend the winter. During the day, however, Big Brown Bats will use a variety of roost locations, including tree hollows and beneath bark*.

*A curious note describes a surprising discovery of a male Big Brown Bat that had been roosting beneath loose bark in a Michigan wetland. While the author of the note was interacting with a data logger in the wetland, “a strip of bark about 1 m in length fell from one of the trees and crashed into the water about 3 m away from me. Mixed in with the bark fragments and covered with duckweed (Lemna sp.) was a half-submerged bat that I eventually identified as an adult male big brown bat.” (Kurta 1994). I was glad to read that the bat was “torpid but unharmed” and after warming up “the bat flew away” (Kurta 1994).

Big Brown Bats are generalist insectivores, consuming basically any insects they can catch. Their diet of hard-bodied insects wears down their large teeth but apparently worn teeth don’t affect their feeding habits. They feed at night, if conditions are favourable (such as not rainy, and sufficiently warm night temperatures). On cooler nights, some bats will undergo torpor (a sort of mini-hibernation state) to save energy and forgo foraging. When they are out hunting, Big Brown Bats use echolocation to find insect prey. Although we think of echolocation calls as strictly for feeding, they inevitably function as signals, sometimes unintentionally. It has been demonstrated that Big Brown Bats are attracted to the echolocation calls of another species of bat (the Little Brown Bat, Myotis lucifugus) and the other species is attracted to Big Brown Bat calls as well (Barclay 1982). This is likely because echolocating bats represent an area with foraging opportunities or food sources.

Big Brown Bat (Eptesicus fuscus). Photo by Sherri and Brock Fenton, used with permission.

Pups are born in June-July in Canada, and begin flying at 21 days or later. In Eastern North America, most Big Brown Bats give birth to twins, while single pups are most often born in Western regions. Although the pups’ wings are the same size as adults, their weight is much smaller, providing them with an advantage while learning to forage. After about a month, the young are able to hunt for themselves (ie. are no longer dependent on nursing from their mothers), but will stick with their mothers for their first few hunts. Some male Big Brown Bats have lived more than 20 years (the demand on females of pregnant foraging and nursing is high and reduces their maximum lifespan).

Big Brown Bats are fascinating, and I was happy to hear and observe them last year. Next up will be the Eastern Red Bat!


Barclay, R. M. R. 1982. “Interindividual use of echolocation calls: eavesdropping by bats.” Behavioral Ecology and Sociobiology, 10: 271-275. cited in: Altringham, John and Fenton, M. Brock, 2003. “Sensory Ecology and Communication in the Chiroptera” in: Kunz, Thomas and Fenton, M. Brock (eds.). 2003. Bat Ecology. University of Chicago Press.

Etymologia: Eptesicus fuscus. Emerg Infect Dis []. 2005, Dec [date cited: February 11, 2023].

Kunz and Lumsden, 2003. “Ecology of Cavity and Foliage Roosting Bats” in: Kunz, Thomas and Fenton, M. Brock (eds.). 2003. Bat Ecology. University of Chicago Press.

Kurta, Allen. 1994. “Bark Roost of a Male Big Brown Bat Eptesicus fuscus.” Bat Research News. Volume 35: no. 2,3.

Naughton, Donna. 2012. The Natural History of Canadian Mammals. University of Toronto Press.

For other mammal-focused posts, see:

Flying Creatures of the Night

Moose (Alces alces) Family

Swimming Squirrels

Top 20 Photos 2013-2020

1. The Pale-Painted Sand Wasp (Bembix pallidipicta)

Subject: Pale-Painted Sand Wasp* (Bembix pallidipicta)

*this species doesn’t have a common name, so I created this common name by using the etymology of its scientific name “pallidipicta” which seems to mean “pale-painted”.

Location: Parents’ Farm, Norfolk County.

Date: July 2013.

For an Introduction to this series (my Top 20 Nature Photos of 2013-2020) go here.

The Story Behind the Shot: While growing up, my brother and I discussed several times the idea of a project: to list every single species that occurred on our family’s property. While this project never reached fruition, the idea of it has inspired me throughout my adventures with the creatures in my own backyard and elsewhere. One day several years ago I spent a day just wandering around on my parents’ farm taking photos of every interesting creature that caught my eye. I was amazed to find busy little wasps digging burrows in the sand at the edge of the field. Despite their frenzied activity I managed to capture one at the entrance of its burrow.

The Story Behind the Species: Bembix pallidipicta is one of those Sand Wasps (members of the subfamily Bembicinae) I’ve mentioned once or twice on my blog about a year ago now. The following information on this species is summarized from Evans and O’Neill (2007).

Not all Sand Wasps construct burrows in sand, but B. pallidipicta does, usually selecting large areas of loose sand to begin their burrowing. Nest site selection is fine-tuned in that they require a small amount of moisture in the sand to maintain a fine crust when they tunnel beneath it. The sites where the females emerge and the males mate are often suitable for the females to use for their nest construction, so unless the habitat is disturbed the same site can support a population of sand wasps for multiple generations. B. pallidipicta males gather around sites where adult females will soon emerge, and fly in short hops, which gives the appearance of “aggregations of very small toads” (Evans 1957).

Once their burrow is constructed with a chamber up to 56 cm beneath the surface (the depth is partly determined by the dryness of the sand), the females lay a single egg at one end of the chamber (termed the brood cell). This egg will hatch and the wasp larva will wait within its subterranean chamber for its mother to provide food. B. pallidipicta exhibits what is called “progressive provisioning” which means that the mother brings prey in multiple times to the larva while it is growing and feeding. I’ve always loved this aspect of sand wasps because it’s essentially the same setup as songbirds awaiting worms in their nests. For B. pallidipicta, the prey is all true flies (Order Diptera) of several Brachyceran families, including Flower Flies (Syrphidae), Horse Flies (Tabanidae) and House Flies (Muscidae). When bringing fresh prey to her larva, the mother will push the fragments of partially eaten prey off to the side, and block this debris off with sand. This likely helps prevent parasites or diseases from accumulating within the nest, or it’s possible that it’s a way for the mother wasp to judge how much more prey to provide. Because B. pallidipicta nests in large unrelated groups, females will occasionally steal prey from other females nearby to feed their own offspring. After about 4 days of feeding, the larva pupates and the mother moves on to construct a new nest.

Another view of the same individual Sand Wasp entering its burrow.

My top 20 Nature Photos of 2013-2020 are going to be presented in chronological order of when I took the photos, they aren’t arranged in any other sort of hierarchy. Come back next time for a photo of a much larger animal caring for its young…

For previous posts about Hymenoptera, see:

-Cuckoo Wasps and Carpenter Bees

The Sand Wasps, Part 1: Introduction

-The Sand Wasps, Part 2: The Tribe Alyssontini

The Social Biology of Wasps (Book Review)

Species Profile: Introduced Pine Sawfly


Evans, Howard E. Studies on the Comparative Ethology of Digger Wasps of the Genus Bembix, cited in Evans, Howard E. and O’Neill, Kevin M. 2007. The Sand Wasps: Natural History and Behavior.

Evans, Howard E. and O’Neill, Kevin M. 2007. The Sand Wasps: Natural History and Behavior.

book review

Flies: The Natural History and Diversity of Diptera, by Stephen A. Marshall

People are always going on about how Beetles are so diverse, biologists are always explaining to theologians that God must really love Beetles*, and whenever anyone asks “What’s the most diverse group of organisms?” Beetles are always top of the list. UNTIL NOW.

*in case you don’t know the anecdote this is referring to, the earliest source (according to runs thus: “There is a story, possibly apocryphal, of the distinguished British biologist, J. B. S. Haldane, who found himself in the company of a group of theologians. On being asked what one could conclude as to the nature of the Creator from a study of his creation, Haldane is said to have answered, “An inordinate fondness for beetles.”” (Hutchinson 1959).

Stephen Marshall proposes in his magnificent volume on the diversity of flies that there are historical reasons why beetles are held up as so diverse when the truth is that they might just be more closely studied than other insect groups… other groups like the order Diptera (true Flies), for instance. And if you read through this 600 page volume loaded with superb photographs and covering every single family of flies in some detail you will come away with the powerful impression that Stephen Marshall is on to something. Flies, a group often neglected because they don’t always photograph well, many look very similar to each other, and a lot of them have distasteful feeding habits, are showcased as the hyper-diverse evolutionary marvel that they are.

Metallic Green Long-legged Fly (Condylostylus sp.), photographed in my backyard, June 2018. I’m just going to post some of the many interesting flies that I’ve photographed myself throughout this article. Stephen Marshall mentions that digital photography is opening up the realms of entomology to amateurs in a way that hadn’t been possible in the past. I wholeheartedly agree!

The book’s first part: “Life Histories, Habits and Habitats of Flies” runs through a sampler of what flies do as larvae and adults. This includes the life cycles of Diptera in general, but elaborates on more specific groups where appropriate. Other sections in this part describe flies interacting with plants, fungi, invertebrates and vertebrates. This entire section comprises about 90 pages and goes into considerable detail on specific guilds* such as the worldwide coastal communities of “wrack flies”, flies that have larvae that feed within decomposing piles of seaweed washed upon shores. Along with the various interactions between flies and invertebrates, this section also includes a discussion of the many human diseases caused or carried by flies such as mosquitoes (Family Culicidae) or house flies (Musca spp.).

*A guild is a group of animals that are united by a common feeding strategy or resource use, but not necessarily united in relatedness. For example, flies from different branches of the Dipteran family tree are considered part of the leaf-mining guild if their larvae produce mines in leaves.

Eutreta novaboracensis, a Fruit Fly of the family Tephritidae, photographed in my backyard, June 2018.

The second part of the book is titled “Diversity” and reading through this catalog of fly families and subfamilies truly does drive home just how incredibly diverse the Order Diptera is. Each chapter covers a large portion of the fly family tree and opens with a diagram of the proposed relationships between the fly groups within. This opening section of each chapter moves from family to family, and describes the basic characteristics of each group detailing subfamilies where possible as well. Within these descriptions are not just lists of characters used to distinguish one family from another but also the basic biology of each group when known. A couple of key things to note here: even when dividing up the flies into smaller and smaller groups it can be hard to generalize because you are still dealing with huge swaths of species in some instances and in others you are simply dealing with species doing very different things despite their close-relatedness. Marshall does a good job of explaining this and I’ll provide an example here from the section on Tipulidae (the Crane Flies, of which there are more than 15 000 described species): “Although most larvae with known biologies are saprophagous and eat microbe-rich organic matter (normally, decaying plant material) in wet environments, some crane flies are predaceous, fungivorous or phytophagous… Some groups have become specialists in extreme environments such as caves, marine intertidal zones and deserts, but most occur in humid forests and wetlands. Most Tipulidae are unknown as larvae.” (Marshall 2012 p. 110).

Crane Fly (Tipula sp.) photographed on the Lynn Valley Trail, May 2018.

The above quote demonstrates the way in which Marshall overviews the lifestyles of the fly groups providing tantalizing glimpses of their diverse life histories, but it also provides an example of something that is rife within the 600 page volume: the overwhelming amount of flies or fly habits that are unknown. To demonstrate, here are some quotes from throughout the book (Marshall 2012):

Valeseguya rieki is known only from a single male specimen” (p 136)

“Larvae and larval habitats of the Lygistorrhinidae remain unknown” (p 141)

“Nothing is known of the biology of these obscure little flies [Ohakunea]” (p 141)

“adults of Oreoleptis (and thus the family Oreoleptidae) have yet to be collected in the field” (p 198)

“The 500 or so species of Acroceridae occur in every part of the world, but most are known from only a few specimens” (p 205)

“Essentially nothing is known about the biology of either Apystomyia or Hilarimorpha” (p 235).

“Even though signal flies [Platystomatidae] are usually conspicuous and attractive flies, many species remain undescribed.” (p 332).

“Larvae are unknown for most species in the family [Lonchaeidae] and little is known about behavior” (p 335).

“The biology of most Pallopteridae species remains unknown” (p 339).

“The truth, however, is that we know almost nothing about the life histories of these bizarre flies [Ctenostylidae]” (p 340)

“Nothing is known about the biology of this group [Nothybidae]” (p 348)

“Despite a worldwide distribution, with about 140 known species spread over every zoogeographic region, not much is known about asteiid biology.” (p 363)

“Nothing is known of the biology of the Neotropical dwarf fly genera [Periscelididae]” (p 365)

The quote list above is not comprehensive, but rather a sampling to show some of the many groups of flies that are mysterious despite their ubiquity in some cases. I don’t want the quotes above to be taken as evidence that the book contains little in the way of information on the flies of the world, seeing as so little is known overall. On the contrary, this volume is chock-full of biological details found nowhere else except the specialized literature and I found myself blown away by many intriguing and fascinating descriptions of fly families and subfamilies. Below are a few of the more interesting groups I had never encountered before reading through this book.

Frog midges (Corethrellidae) are attracted to singing frogs where the females feed on the frog’s blood. Some Phorid flies lay their eggs inside ants, where their larvae consume the ant’s head from the inside. After feeding within, the larvae decapitate the ants and pupate within the armored shelter before emerging as adult flies. These flies are known as ant-decapitating flies, and there are more than 300 species of them in the genus Apocephalus. Vermileonidae is a family of flies known as “wormlions” which are essentially the antlions of the diptera, their larvae constructing cone-shaped pits to trap wandering insects for prey. The Fergusoninidae is a family of flies that “develop only in galls induced by a specialized and codependent group of nematodes” (Marshall 2012, p 366).

Probably my personal favourite are the smoke flies. The smoke flies, platypezid Microsania spp., are attracted to fires (even campfires) but are rarely seen elsewhere. The smoke fly swarms are often followed by the predatory empidid dance fly Hormopeza which “seems to be a specialized predator of smoke flies. Like Microsania, the smoke dance flies are rarely seen except when they appear in plumes of smoke.” (p 298). I feel like the smoke flies, a group of species that can be attracted to something as common as a campfire, and yet are known from basically nowhere else (and thus poorly understood biologically) perfectly encapsulate the mystery and wonder of flies that I have gained from reading this book.

All of this fascinating information is found within the comprehensive and authoritative text, and after going through family by family in this fashion, each chapter in the “Diversity” section has a “photographic guide” portion which covers representatives of most subfamilies with further notes on natural history and significance of genera pictured. The scope of the pictures is mind-boggling and further bring home the diversity of flies, as well as their surprising beauty.

Transverse-banded Flower Fly (Eristalis transversa), photographed in my backyard, September 2018.

The final, shortest section covers collecting, preserving and identifying flies, and contains notes for those interested in starting insect collections of their own (as in, pinned specimens) as well as keys for identifying the major fly groups.

I can honestly say that if this book were published with only the text portions I would buy it because the text is just that valuable in overviewing the enormous diversity of the fly families. And I can also say that if this book were published with only the pictures and captions, I would also buy it for the incredible amount of biodiversity on display, captured in wonderful images of flies from around the world.

I cannot recommend this book highly enough. If you are an insect enthusiast, if you are at all interested in the diversity of life and if you enjoy gasping at revelations about the tiny wonders that flit around the world you have to read this book.


Hutchinson, G. E. 1959. “Homage to Santa Rosalia or Why Are There So Many Kinds of Animals?” The American Naturalist93(870), 145–159.

Marshall, Stephen A. 2012. Flies: The Natural History and Diversity of Diptera.

For previous book reviews, see:

The Paleoartist’s Handbook, by Mark Witton

The Social Biology of Wasps, ed. by Kenneth Ross and Robert Matthews

Pterosaurs, by Mark Witton

Flora of Middle-Earth, by Walter Judd and Graham Judd

And for a podcast review, see:

The Field Guides

Natural Curiosities

Natural Curiosities, Part 1: Emu Feathers

My wife recently ordered me a bag of assorted natural curiosities from a seller on Etsy, Biophilia Supply. They sell ethically sourced nature items for use in decoration or education. In my case, it was for education. I’ve collected the odd natural curiosity myself from time to time (a few insect exuviae, a few dead insects, and a few fossils) and maybe I’ll write about some of those at some point in the future. The excitement of this Biophilia Supply grab bag of items was the variety and rarity of the items themselves. Through this series of posts I’m going to explore the items I received, and the organisms they came from.

Emu (Dromaius novaehollandiae) Body Feathers

Name Discussion: Dromaius novaehollandiae. Dromaius means “racer” in Greek, and the species name “novaehollandiae” is a Latinized version of New Holland, which is what Dutch explorers and sailors called Australia for a while in the 1700s.

Range, Relatives and the Ecology of a Flightless Bird: I have never seen an Emu, except maybe in a zoo, because they live across mainland Australia (though they used to also live on the neighbouring island of Tasmania). There also used to be two other species in the Family Dromaiidae (D. ater and D. baudinianus), but they were both island populations exterminated by humans in the 1800s. Their feathers have “barbs so widely spaced that they give the plumage a loose hairy appearance” (Davies 2002). I’m not exactly sure why Emus have hair-like feathers, but they certainly don’t need them to be stiff like the flight feathers of many other birds because Emus can’t fly. Emus can grow to almost 2 meters tall, and are the second tallest bird in the world, only behind the Ostrich. Emus are nomadic birds, traveling to places that have recently experienced rain and will gather in large numbers at abundant food or water sources. Although they inhabit the edges of deserts, they are always on the move to reach the most productive areas. Another adaptation for their dry and difficult habitat is to eat the richest foods they can find: Emus eat fruit and seeds as well as various species of insects.

Photo By JJ Harrison ( – Own work, CC BY-SA 4.0,

Next up: Bison hair, Porcupine quills or the shed skin of a snake.


Davies, S. J. J. F. Ratites and Tinamous, 2002.

Species Profile

Introduced Pine Sawfly

Diprion similis

Diprion similis larva at Algonquin Provincial Park, September 2019.

Sawflies are a group of insects that many people haven’t even heard of. Part of the reason is because, in appearance and behaviour, they are like a hybrid between two major groups: their larval stages look like caterpillars (larvae of Butterflies and Moths ie. Lepidoptera), and their adult stages look like bees or wasps (Order Hymenoptera). Despite appearances and lifestyle, it is the latter category that they actually fall under: Hymenoptera which also includes the Bees, Wasps, and Ants. The major features that set sawflies apart from their relatives is that they eat plants, and they don’t have the constricted “wasp waist”. You might find this a little confusing, as Bees certainly don’t have an obviously thin waist, but they actually do have a constriction between their thorax and abdomen, it’s just more difficult to see than in many wasp species.

Like many insect Orders, the name Hymenoptera refers to a distinct aspect of the members’ wings (‘ptera’ is derived from the Greek for wing). Hymenoptera doesn’t have an easy translation though, like say Diptera for the True Flies (di = two, ptera = wings). The beginning part of the word is either from the word “hymen” which means membranous, or from the word “hymeno” which refers to the Greek God of Marriage. Hymenopteran wings are membranous, but they also have tiny hooks that link their fore- and hind-wings, meaning that they could be said to be “married” wings as well (Grissell, 2010). Whatever the case, the group is one that includes thousands of species of wasps, bees, ants, and of course, sawflies.

The common name “sawfly” is describing the way the female sawfly lays her eggs. Instead of a stinger or stinger-like ovipositor (egg-layer) at the end of her abdomen (like most of the other Hymenopterans), the female sawfly has a saw-like ovipositor, a cutting tool that she uses to open up plant tissue, and then inserts her eggs within.

This is what the Introduced Pine Sawfly (Diprion similis) does to pine needles. D. similis prefers White Pine (Pinus strobus) as its host plant (in North America), but will lay eggs and successfully grow to maturity on several other pine species. The female lays about 10 tiny eggs inside a pine needle (Cranshaw, 2004). After inserting the eggs, the female seals them in with a secretion that hardens for protection (Wagner and Raffa, 1993). The larvae that hatch from the eggs begin to feed on the pine needles. For the first part of their life, they will remain together but begin to disperse as they grow older. These larvae prefer to feed on needles that are at least 1 year old, probably because the younger needles are full of more toxins (Wagner and Raffa, 1993). As they consume needles, they grow, from 2.5 mm long upon first hatching to almost 3 cm before the larva is said to be “mature”. They don’t grow continuously, but rather have to molt and enter a new size class each time they’ve gained enough nutrients. For female larvae, they have six growth stages between molts and the males have five (CABI, 2020).

During this time, you would be forgiven for thinking they were caterpillars, because they look very similar. The way to tell caterpillars from sawflies is to count the number of legs. Their first set of legs will be six, and jointed for both groups, but they will also have a number of legs behind these called “prolegs”. If the larva you’re looking at has more than 5 pairs of prolegs, it’s a sawfly. Another giveaway is the distinct single eyes of sawfly larvae, as opposed to tiny ocelli (miniature eyes in clusters) in caterpillars.

Once they’ve reached their final larval stage, they spin a cocoon around themselves with silk, and transform within. Diprion similis larvae prefer to form their cocoons in the pine trees where they feed, rather than on the ground like many other sawflies.

In Europe and most of North America there are two generations per year, which means that what happens next depends on what time of the year it is. If the larvae have grown enough and created their cocoons in the summer, they will develop within in about 2 weeks into adults, but if they have reached this point near the end of fall, they will enter diapause (essentially insect hibernation) for several weeks before emerging in the spring (CABI, 2020). When they emerge, the adult sawflies are entirely different creatures, just as butterflies and moths are very distinct from their caterpillar young. The adults have wings, and with these they search for mates.

Adult Male D. similis, displaying the feathery antennae used to track down a female (Photo credit: Scott R. Gilmore.)

Males are attracted to females by pheromones (a chemical signal between members of the same species), as one would guess by the male’s elaborate antennae. The males can be attracted to a female across 61 m of open field, which is a great distance for an insect only a matter of centimeters long (Wagner and Raffa, 1993). Once mated, the female lays eggs in pine needles, and we are back at the beginning of their life history.

One note about mating: it isn’t necessary for the female to mate to be able to lay eggs. She shares with the other Hymenoptera a bizarre (to us) chromosome setup known as haplodiploidy. Females have one set of chromosomes (the mother’s) and males have two (mother and father). What this means in practice is that a female sawfly can lay an egg that will develop into a fully functional male offspring without ever going through the trouble of mating. This has implications for the spread of such organisms, as not all members of the population need to pair up to contribute to the next generation.

Which brings me to my final discussion of this species: they are commonly referred to as the Introduced Pine Sawfly because they were accidentally introduced into North America from Europe, likely in plant nursery stock imported in 1914. They have become well established in North America since then. Thankfully, they only very rarely reach a high enough population density to be considered an “outbreak” invasive species, and though they feed on tree leaves (needles), many predators and parasitoids feed on them (Wagner and Raffa, 1993).

The last time we were camping at Algonquin Provincial Park, I encountered quite a few of their larvae likely because they were in the fairly mobile phase before finding a spot to spin a cocoon (it was the end of September, the beginning of October). They may be an introduced species, and they may feed on White Pines, defoliating some of the branches, but as with any organism, they have a story all their own, and I think it’s worth telling.

Diprion similis larva hanging onto the end of a pine needle in Algonquin Provincial Park.


Wagner, Michael R. and Raffa, Kenneth F. Sawfly Life History Adaptations to Woody Plants, 1993.

Cranshaw, Whitney. Garden Insects of North America. 2004.

Marshall, Stephen. Insects: Their Natural History and Diversity. 2006.

Grissell, Eric. Bees, Wasps, and Ants. 2010.

CABI, 2020. Diprion similis. In: Invasive Species Compendium. Wallingford, UK: CAB International.