Ducks Unlimited
Tuesday, 31 October 2017 02:44

A duck in spring - in Canada

Each spring, Canadians herald the sights and sounds of waterfowl as they flock to their nesting grounds. But after their long trips, life for our feathered friends isn’t easy. Ducks – especially females – undergo arduous physical and biological processes before, during and after their journeys. And once here, most hens have one shot to raise a brood.

It’s early June on the Saskatchewan prairies. A slight breeze gives her wings a lift as she circles over a patch of native grassland next to a shallow pond. She decides to land in a small clearing, then walks into the grassy cover. It’s the third spot she’s scouted. She feels safe here.

In the coming days, this blue-winged teal hen will construct a nest with nearby vegetation and line it with down plucked from her breast. She’ll feed on invertebrates to build her energy for an important role: producing a brood.

It’s no easy gig. She’ll need all the energy she has to give.

When male and female waterfowl prepare for their journey from their southern wintering grounds northwards to Canada, they do so in similar ways. The process differs between the sexes once they arrive. David Howerter, PhD, director of national conservation operations at Ducks Unlimited Canada (DUC) explains how, and why ducks do what they do – before and when they get here.

A shared experience: preparing for migration

Feeling restless – Ever wonder what pushes migratory waterfowl to bid adieu to their warm winter homes?

It’s a physiological process called zugunruhe (pronounced: zoo-gun-roo). This German term refers to the restlessness birds experience as migration nears. Zugunruhe is triggered by the endocrine system (a collection of glands that release hormones into their blood stream) in response to longer daylight hours. “As it gets closer to the time for these birds to migrate they become increasingly active,” says Howerter. “They’ll spend more time flying and their movements will begin to orient in the direction they intend to migrate.”

No exceptions – Zugunruhe impacts migratory waterfowl wintering close to the equator, where daylight hours remain consistent, year-round. This may be a result of evolutionary hangover from when the species had a different distribution, or because of the changing angle of the sun.

Packing on the pounds – “Before ducks begin their journey north, they’ll go through a phase biologists refer to as hyperphagia, where they’ll spend a lot of their days consuming calories,” explains Howerter. “This is done to prepare for their long trip.” Like zugunruhe, hyperphagia’s also triggered by hormonal changes, influenced by changing daylight hours.

Growing closer – Migratory waterfowl can only procreate from spring until late summer. This is because in the “off-season” their reproductive organs shrink, making it easier to fly over long distances. As birds close in on their breeding grounds, their endocrine system releases hormones that stimulate their reproductive organs to grow larger again in anticipation of breeding.

It’s all about her: producing a clutch

Once waterfowl arrive at nesting sites, the male-female experience begins to diverge. “Once they have fertilised the eggs and the hen is incubating, the drakes will take off. Often they’ll go further north, to the boreal forest,” says Howerter.

Meanwhile, the hens prepare for one of the most difficult processes they’ll go through in their lifetime: producing a clutch of eggs.

Size matters – How waterfowl behave once they arrive at the nesting site depends on whether they’re capital or income breeders. “Capital” breeders are large-bodied ducks that can store enough energy (calories) to migrate thousands of kilometres and arrive ready to lay a clutch of eggs, and incubate them for about 30 days. One example of a capital breeder is the common eider, which averages between two and six pounds.

“Income” breeders like the far smaller blue-winged teal (weighing in at 400 grams) are unable to sustain the same kind of fuel reserves. When they arrive at the nesting grounds, they’re looking for protein- and calcium-rich foods, like invertebrates, that provide the nutrients they need to produce a clutch of eggs

Medium-size waterfowl like mallards fall somewhere between capital and income breeders. “Birds of average size usually have enough nutrients to initiate the first clutch of eggs, but they don’t have enough reserves to re-nest,” says Howerter. However, some duck species (like mallards, which are persistent re-nesters) will produce a second or third clutch if their first one is unsuccessful.

Nesting is natural – Birds, like people, experience the urge to nest before they welcome offspring into the world. Expectant bird and human parents alike can trace this feeling to the hormone prolactin. Prolactin is released into the blood stream by the pituitary gland, found at the base of the brain.

Laying a clutch of eggs – A hen’s pituitary gland will also release two hormones that stimulate egg production: follicle-stimulating hormone and luteinizing hormone. They trigger ovulation. Once a duck begins to ovulate, a drake can fertilize her egg – then things begin to take shape. “Once the ovum is fertilised the egg starts to develop. 

The yolk provides nutrients to the developing embryo and albumen (egg white) is deposited around it, followed by the shell. About seven days later, the hen will lay an egg,” says Howerter.

A blue-winged teal hen will lay between six to 14 eggs, provided she has the energy required to develop them. “Producing a clutch is very energetically expensive,” says Howerter. “In humans, it can be compared to giving birth to an eight-pound baby once a day for nine to 10 days.”

Sitting still – Once a duck has laid her eggs, she will spend nearly one month incubating them. While some ducks, like common eiders, will stay on their nest nearly continuously, other birds take more frequent breaks to eat. “But even they will lose roughly 30 per cent of their body weight,” says Howerter. In some cases, hens may abandon their clutch if conditions become unfavourable (bad weather, predators, disease).

Crack! – The eggs have hatched. Finally, mom can focus on relaxing and refueling, right?  “Not exactly,” says Howerter. Instead, she’ll help her ducklings find food high in protein and calcium, required for muscle and skeletal development. While ducklings are precocial (mobile after hatching), they still need help to find suitable habitat and food.

Bidding farewell – After 30 to 40 days, many hens will leave their broods to prepare for moulting (the process in which ducks lose their flight feathers). “The ducklings are on their own after that,” says Howerter, noting at this point young waterfowl are able to source their own food. At a month old, ducklings are also faster and stronger, making them far more difficult for predators like foxes, raccoons, red-tailed hawks and mink to catch and eat.

Back amidst the grasses, the blue-winged teal hen has hatched a healthy brood of ducklings and led them to the nearby wetland. In future years, these ducklings will return to the prairie landscape to produce their own offspring and repeat this fascinating but strenuous process of duck-rearing.

Continuing that cycle depends on a key ingredient, says Howerter. “Good habitat across Canada’s waterfowl breeding grounds is essential to overcoming the many challenges of successful reproduction for returning birds.”

Healthy and plentiful habitat. It’s the best welcome mat we can roll out for waterfowl every spring.

Julielee Stitt

Communications coordinator for Ducks Unlimited Canada.

Published in Issue 172
Monday, 04 September 2017 12:35

What are Waterbirds?

If you have never heard of many of these birds, you are not alone.
Waterbirds have been defined as “species of bird that are ecologically dependent on wetlands”.
1.This is the definition used by the Ramsar Convention on Wetlands.
For the purposes of the International Waterbird Census, all species in the following families are considered by Wetlands International to be waterbirds: Gaviidae (Divers/Loons), Podicipedidae (Grebes), Pelecanidae (Pelicans), Phalacrocoracidae (Cormorants), Anhingidae (Darters), Ardeidae (Herons), Scopidae (Hamerkop), Ciconiidae (Storks), Balaenicipitidae (Shoebill), Ciconiidae (Storks), Threskiornithidae (Ibises and Spoonbills), Phoenicopteridae (Flamingos), Anhimidae (Screamers), Anatidae (Ducks, Geese and Swans), Gruidae (Cranes), Aramidae (Limpkin), Rallidae (Rails, Gallinules and Coots), Heliornithidae (Finfoots), Eurypygidae (Sunbittern), Jacanidae (Jacanas), Rostratulidae (Painted Snipes), Dromadidae (Crab Plover), Haematopodidae (Oystercatchers), Ibidorhynchidae (Ibisbill), Recurvirostridae (Stilts and Avocets), Burhinidae (Thick-knees), Glareolidae (Coursers and Pratincoles), Charadriidae (Plovers), Scolopacidae (Sandpipers, Snipes and Phalaropes), Pedionomidae (Plains Wanderer), Thinocoridae (Seedsnipes), Laridae (Gulls), Sternidae (Terns) and Rynchopidae (Skimmers). Only a few wetland birds are excluded by considering entire families in this way. Conversely, the inclusion of whole families results in the waterbird list containing a few non-wetland species such as some coursers and thick-knees. These rather minor anomalies are thought to be outweighed by the convenience of a whole-family approach to the definition of the term ‘waterbird’ and, in particular, considering the complications that would arise from applying the definition rigidly to every species.
The Ramsar Convention on Wetlands recently widened its approach to include more families traditionally regarded as seabirds, as well as certain raptors and passerines, and it is possible that a small number of additions will be made in the coming years to the families and species included in the IWC.
2. Why count waterbirds?
The International Waterbird Census uses information collected by four continental-scale censuses over the long term to provide crucial information which underpins conservation of waterbirds and their wetland habitats. The aims of the census are as follows: To monitor the numerical size of waterbird populations; To describe changes in numbers and distribution of these populations; To identify wetlands of international importance for waterbirds at all seasons; To provide information to assist protection and management of waterbird populations through international conventions, national legislation and other means. The rationale behind the census was summarised eloquently by Matthews (1967) at the time when international coordination of waterbird counting was beginning: “..while man is recklessly unleashing new insults on his environment, background monitoring of populations is essential to detect the threats as they develop and before they become catastrophes apparent to all”.
Waterbirds are well-known indicators of the quality of certain types of wetlands. A powerful tool which makes use of this characteristic is the so-called 1percent criterion, whereby any site which regularly holds 1percent or more of a waterbird population qualifies as a wetland of international importance under the Ramsar Convention on Wetlands. The 1percent criterion
has been adopted by the European Union to identify Special Protection Areas (SPAs) under the Birds Directive. It is also used by BirdLife International in the identification of Important Bird Areas (IBAs) in wetlands throughout the world.
Standardised monitoring of Arctic breeding species, and species dependent on inter-tidal habitats is even more important in the light of human induced climate change, the seriousness of which is now generally accepted (Houghton et al. 2001). Global warming is expected to have especially pronounced effects on tundra and other Arctic environments, and, through sea level rise, on intertidal habitats (Boyd & Madsen 1997). The IWC will play a significant future role in monitoring the effects of these changes on the millions of waterbirds which depend upon these habitats.
3. What is the International Waterbird Census?
The International Waterbird Census (IWC) is a site-based counting scheme for monitoring waterbird numbers, organised since 1967 by Wetlands International, formerly the International Waterfowl and Wetlands Research Bureau (IWRB). The Census operates at a global level, and the former division into four separate continental-scale surveys was superseded in 2003 by a new strategy for global coordination. Coordination at continental level takes place as follows:
• Global coordination, and the counts in the Western Palearctic and southwest Asia are organised from Wetlands International
headquarters in Wageningen, The Netherlands.
• The African Waterbird Census is coordinated from a sub-regional office in Dakar, Senegal, which began operating in 1998.
• The Asian Waterbird Census, which includes Oceania, is coordinated from Wetlands International’s Asia Pacific office in Kuala Lumpur, Malaysia.
• In the Americas, the Neotropical Waterbird Census is coordinated from the Americas office of Wetlands International in Buenos Aires.
• Establishment of IWC in North America began in 2003, from a new Wetlands International office in Washington DC. The census takes place every year in over 100 countries with the involvement of around 15,000 counters, most of whom are volunteers. More than half the effort is concentrated in Europe, but involvement in other parts of the world has increased markedly since 1990. Between 30 million and 40 million waterbirds are counted each year around the world, and details of the counts and the sites where they take place are held on the newly upgraded, state-of-the-art IWC database. The IWC is thus by far the longest running and most globally extensive biodiversity monitoring programme in the world.
4. How to count waterbirds.
Anybody who can identify birds can contribute to waterbird monitoring activities. Identification Correctly identifying all the waterbird species present at a site is the first necessity of waterbird counting. Bird identification is a skill which takes time to master and beginners make more mistakes and miss more scarce species than experienced observers. Correct identification includes a process of elimination, and knowing which species are most likely to occur at a site in a particular season reduces the number of species that need to be eliminated from consideration.
The best way to learn is to spend time in the field with an experienced observer who knows which species to expect and who is familiar with the field characteristics of each species. Careful and copious note-taking and field sketching also enhance an observer’s powers of observation and reinforce memory of field characteristics.
This manual is not an identification guide, and when learning to identify birds, time should be spent consulting identification guides and becoming familiar with the plumage patterns, behaviour and annual cycles of each species. Videos and CD RoMs are also available which provide additional “homework” material for those learning to identify birds, but there is really no substitute for experience in the field, preferably under the guidance of a knowledgable birdwatcher.
Any experienced birdwatcher can count waterbirds, and a count on foot of a small to medium sized site is quite a straightforward undertaking. The methods used to count waterbirds in the field depend on many factors, for example: - the species being monitored;
- the size of the site; - the accessibility of the shoreline; - the availability of vantage points from which the site can be scanned; - the amount of time available to complete the count; - the number of people involved; - the available equipment. The most important element of waterbird monitoring methodology is standardisation.
Want to know more?– check out Wetlands International online.
Published in Issue 170
Monday, 04 September 2017 00:11

Photo Competition

Flight will have space for three winners from each of three categories.
So take your camera where ever you go these coming months. We are looking for photos of ducks and other water birds. Or good scenic shots of the wetlands where they live.

Published in Issue 170