That's it for us tonight. Join us Jan 7 to learn what happens when fresh water ecosystem gets salty...in the meantime, take care, enjoy the winter break, and get lots of rest (especially you parents!)

Let's end on a high note though: parasitic castration. Sacculuna barnacles attach themselves to history crabs, taking over its hormonal machinery to care for its own young. Only female crabs will do, so if a barnacles finds a male, it'll feminize him. That's complicated parenting!

True parasites, however, always get other species to do the work for them. Cowbirds are a local example, but Cuckoos are of course most famous to this end. (They're even skilled egg mimics! Could you spot the difference?)

But perhaps the king of cost cutting is simply dumping eggs in other nests. Coots try this, spreading their eggs outside their own nests. Wood Ducks and Mergansers end up doing this a little by accident do to limited nest sites (mixed broods can follow, with imprinted x-species ducklings!)

Or, there's always babysitting (aka alloparenting). Canadian Geese are pro at this, keeping big crèches of goslings. It's not that much of a burden to add more yellow fluff to the group, since they feed themselves.

So why not get cooperative? Greater Anis pool together and nest in groups. This helps with the shortage of nest sites, but doesn't give much in the way of active care (cool birds tho!).

Less commonly, birds like the African Jacanas can do polyandry. A female lays multiple clutches of eggs for different male partners, who keep the nest. Great for her a lot of the time, but it leads to egg trampling between rival females.

Some species shift between polygyny (1 male + multiple female partners) + monogamy. When a male controls enough resources to keep a bit of a harem, his reproductive success goes up, but females don't perform as well as their monogamous peers.

What about social monogamy? It helps males chill out a little and compete less. They might even help out around the nest. But with a species like the Hooded Warbler, there's about a 30% chance that they aren't the genetic father of all those eggs. On the plus side, genetic diversity?

Secondly, courtship is also taxing! For promiscuous species, like say Bowerbirds, males have to build beautiful architectures, mimic songs, do complicated dances, and may.... come up empty. Plus the female still ends up doing all the parenting alone.

First off, brood size really matters. Having more babies means that parents become much more likely to die, in some species, or less likely to have the regular amount of eggs next season, in others.

(Not relatable in a 1:1 way, but ooof, we see you, birds!)

In fact, you can catch us tonight with a fascinating look at cuckoos! How do bird brood parasites offload the work of parenting? Dr. Alexander Mills will give us the scoop, starting at 7:30 (though do come a little earlier to guarantee yourself a seat). If you can't make it, we'll skeet it out here.

We run a(n almost) monthly pub talk series: the Conservation Cafe! Every month during the academic year we invite an expert to the upper floor of the Publican to share their work and love of conservation science and ecological restoration. Our events are free, fun, and open to all (with a cash bar)