Breeding Biology

Pair formation

So what starts off this expedition to an amazing nesting site? Dedicating a life to their ducklings? Well it begins with pair formation. Males ducks become very showy in order to entice the female onlooker while the female remains drab for optimal camouflage in order to protect the nesting site. The primary reason why males are so showy in ducks is because they are polygamous, meaning one male will obtain many females either during a mating season or at least in his life time. This means that they must look as fit as possible to obtain the females, they are in constant competition to get the ladies. However, the larger counterparts of the waterfowl world, geese and swans are not sexually dimorphic and therefore many of them are monogamous for life. This means they do not need to spend a lot of energy to seduce the females ducks into mating. The showy Bufflehead is one of the only ducks that breaks the trend of polygamy and will mate with the same female for many seasons (Check out more about the Bufflhead lifestyle, check the other blog post about Bufflheads).

During the breeding season, females greatly benefit from pair formation. The male will usually watch out for predators and defend territories so that their females can get optimal food reserves. For male ducks, at least, the breeding season is costly to them due to the fact they must upkeep their showy plumage.

This is a ruddy duck penis is in the shape of a crockscrew and is one of the largest in the animal world. The bar is 2cm for scale. This video shows the erupting penis from a  Muscovy Duck (Cairina moschata).  It was mentioned in this book: The Dawn of the Deed by John Long. He said that the the Muscovy duck is able to erupt it's penis within 0.4 seconds.


Time to nest
The best time to nest is when food is at the highest point. For example, the Laysan duck of Hawaii needs to ensure that it's ducklings will have sufficient amount of food when they hatch. So they do this in correlation with the brine flies.
Correlation of abundance of Brine Flies and nesting season
Breeding range 
Birds typically attempt to breed as far north as possible where there is plentiful food. However, with larger waterfowl populations, the less competitive species breed at lower latitudes. The preferential thing to do is to breed close to wintering grounds in order to minimize risky journey while migrating.

In class, we discussed as a group what we would do to create the most beneficial nesting site for ducks, or a duck in particular. So when we want to think of the placement of nest, what are things we should take into consideration?

• Will the nest site flood?
• Is the nest cryptic enough?
• Potential predation?

• Do they nest in the rocks...cavities...trees?

• Are the females endogenous or exogenous? Will she need to travel to find food?
• How densely packed are the nests?

We decided to choose the wood duck and created a sketch of what we thought would be most appropriate for the wood duck:

Egg and clutch size

If you view Element 1, you will see the wide range in clutch sizes. Ruddy ducks, for example, will lay eggs throughout the incubation time larger in mass than themselves. Although the rule goes, the larger an egg is in relation to body size, generally the clutch will be smaller.

Incubation

Female birds have a brood patch. This means they pluck away down in order to display a bares kin spot. With this patch, they lay on the eggs and warm them with close body contact to the eggs. For ducks, many males do not help the female with incubation. Geese and swans, however, will share the responsibility by the males guarding the territory and the female incubating. Emperor Geese are the most loyal egg layer, staying with the nest for 99.5% of the incubation period.

Renesting
Swans and geese do not renest. However, ducks do so long as the renesting occurs early enough in the incubation period. The environment in which ducks live in is hardly in favor of their nest surviving. Usually the older birds renest because they tend to be more fit and begin nesting earlier than the younger ducks.
Hatching and rearing
The most amazing thing I read about waterfowl thus far is the unhatched offspring, will begin to make calls to the outside world to their parents in order to synchronize hatching two days before hatching.






Growth & Development of young

Ducks are fortunate because there is so much energy put into the egg, that as soon as the egg hatches, within a few hours the ducklings are fluffed up and ready to walk. Ready to feed themselves, eyes open, waddling little bodies into the dangerous world. The main responsibility the mother has is protection. Once out of the nest, the world is a scarier place, with the protection of mom from predators or interspecfic competition, the ducklings are much safer.
Here's an interesting little story about a mother duck saving her duckling from seagull predation.



The main things I gathered from the Barnacle Goose breeding biology is they choose their mate according to:

1. Size of partner
2. Age of partner
3. Region the partner was from

But mainly, these three criteria were selected for  more frequently if it was similar between the mating pair. Similar age, natal site, and size of partner resulted in the most pairs. 

Also, it seemed as though younger geese attempt to mate, but they rarely do so successful. From my own opinion, I hypothesize that even though they most likely won't be able to do it, yet they still put energy reserves in it, I hypothesize that it is due to gaining more practice and experience at tending to young. I derive these predictions from the fact that once there is too much energy that needs to be invested in young, the Barnacle Geese will usually abandon a nest or goslings when it is too difficult. If they invest all of their time into a clutch that will most likely not survive, then they are potentially going to lose the chance to reproduce successfully in the future. Say, they stay on their nest too long to incubate and there is no food around, they will lose valuable nutrients for a clutch that was not going to survive anyways due to lack of experience. They abandon the nest when it becomes to energetically demanding and when there is a loss of experience gained. Only 17% of the population ever reproduce successfully anyhow.