I spent most of today researching and cross examining photos of US/Canada Turdidae (thrushes) nests. I got the idea of making posts like this from a comment @beartracker made on the neglect of a nest/egg field guide. I will be posting more of these nest/egg identification posts but for now, I'm starting out small and doing it family by family. So here you go!

Bluebirds-- Genus Salia

There are three species of Salia or bluebirds, the Eastern (S. salia), Western (S. mexicana) and Mountain (S. currucoides). They are fairly easy to identify because they are the only thrushes that nest in cavities or birdboxes. I've even seen a few iNat observations of bluebirds even nesting in hollow metal gate polls. Nests are usually made entirely of fine grasses and straw. Eggs are a vivid blue though white clutches can occur.

Since nesting sites, materials, eggs and even nestlings are nearly, if not, identical among the three bluebirds, most sightings will have to be identified by range. Mountain Bluebird eggs are however on the lighter blue of the spectrum, so darker blue eggs in western US are going to be Western Bluebirds. But since Western Bluebird eggs vary from dark blue to white, all other eggs are best left at genus unless a parent was spotted.

Brooding Periods:
Eastern Bluebird -- Feb-Oct -- 3-5 eggs
Western Bluebird -- Apr-Aug -- 2-8 eggs
Mountain Bluebird -- Apr-Sep -- 4-8 eggs

Eastern Bluebird Eggs (blue and white) along with nearly fledged young.
https://www.inaturalist.org/observations/6891991
https://www.inaturalist.org/observations/21835712
https://www.inaturalist.org/observations/30339752

Western Bluebird Eggs and half-grown nestlings.
https://www.inaturalist.org/observations/25361200
https://www.inaturalist.org/observations/24642607

Mountain Bluebird Eggs (blue and white).
https://www.inaturalist.org/observations/6415727
https://www.inaturalist.org/observations/26904397

Solitaires Myadestes

There's only one breeding species of solitaire in US and it's the Townsend's Solitaire (M. townsendi) of western US. They are the most unique nesting thrush in North America because they are the only thrush that lays white or cream colored eggs with brown speckling, very similar to Passerellidae or New World Sparrows. They make a nest made of pine needles and grasses on top of a cutbank. Forest roads that cut into the mountain are perfect places to look for a nest. Eggs or young can be found in nests between May and July. Here's a couple photos of eggs in nests.

https://www.inaturalist.org/observations/13105721
https://www.inaturalist.org/observations/6842002

Varied Thrush Ixoreus naevius

No need to explain what species this is. unfortunately, no photos showing nests or eggs. Varied Thrush nest are hard to come by, since they nest in dense, thick, wet mature forests. They seem to always nest in young pines close to the trunk with the nest contains being moss, mud and grasses. Eggs are blue with black speckling.

Brown Thrushes Catharus and Hylocichla

There are seven species of brown thrushes breeding in North America and in taxonomic order; Veery (C. fuscescens), Gray-cheeked Thrush (C. mimimus), Bicknell's Thrush (C. bucknelli), Swainson's Thrush (C. ustulatus), Hermit Thrush (C. guttatus) and Wood Thrush (H. mustelina). Since eggs and nests are so similar among the species, I think this graph will better illustrate how to identify nest and eggs.

Ground nest with solid blue eggs -- Veery and Hermit Thrush
Ground nest with blue eggs with speckles -- Swainson's Thrush, Hermit Thrush (speckling rare) and Gray-cheeked Thrush (ground nesting rare)
Bush/tree nest with solid blue eggs -- Hermit Thrush (western US only) and Wood Thrush
Bush/tree nest with blue eggs with speckles -- Gray-cheeked Thrush, Bicknell's Thrush, Swainson's Thrush (tree nesting rare) and Hermit Thrush (speckling rare).

When given this information, you can cut down 7 species, though you probably have less in your state/province, to 2 or 3 species. Keep in mind that breeding behavior for Hermit Thrushes differs geographically with western US birds typically nesting in shrubs or trees while eastern US birds are ground nesters.

Veery nest with eggs, including a cowbird egg. Note that cowbirds strongly parasitized Veery and this can be used for identification.
https://www.inaturalist.org/observations/32429131

Gray-cheeked Thrush nest with incubating mother.
https://macaulaylibrary.org/asset/478063#_ga=2.9695223.374957309.1581564560-1175263981.1555651889

Bicknell's Thrush nestlings.
https://www.inaturalist.org/observations/173108

Swainson's Thrush eggs.
https://www.inaturalist.org/observations/30180919

Hermit Thrush eggs.
https://www.inaturalist.org/observations/11472489
https://www.inaturalist.org/observations/173085

Wood Thrush eggs with cowbird egg.
https://www.inaturalist.org/observations/5613925

American Robin Turdus migratorius

Robins are fairly easy to identify nests. They are only North America thrush that nests in trees with the exception of the Wood Thrush. They also have a tendency to nest on eaves, buildings and wherever urban. The best way to identify their nest from a Wood Thrush is that robin nests are made of grass and mud while Wood Thrush use grass and leaves.

American Robin eggs and a building nest with nearly fledged young.
https://www.inaturalist.org/observations/10746503
https://www.inaturalist.org/observations/3318345

And those are the thrushes of North America. Hope this helps!

First off, I would like to thank all of those who have joined this project and I really appreciate the time you've taken to join the project and save me some time to add your observations. I would've never expected my project to be this big a week after its creation. So once again, I thank you for your time.

Unfortunately, after a week, I've already encounter some problems with the project and I want to address the issue before it becomes such a big problem, I can't fix it. I had to remove a bunch of observations this morning because they fell short of project requirements. The first example being, I received a bunch of reptile eggs like turtles and snakes. And if you go to the About section of Active Nests, the first statement I made in regards to the project is, "This project is to compile all "active" nest observations of birds across the world."

So the clarification here is, this project is only for bird nests or eggs and nothing else. All nests or eggs that are not birds, such as reptiles, amphibians or insects, will be removed from the project.

Second problem I've encounter is well... there's no nice way to say it. I've also been seeing eggshells or nest-less eggs being added to the project. So here's the clarification. This is a project for active nests, not evidence of nesting. Adding these observations muck up data because we're trying to understand when birds breed. So if you add an eggshell or even an old nest in October when the species is a May-August breeder, that messes with the data. So once again, I plead with the fact this is only for active nests. If you have eggshells, old nests or anything else, there are plenty of other nest projects to submit them to. All sightings of inactive nests, eggshells or nest-less (unless its a species that normally does not build a nest like shorebirds) eggs will be removed from the project.

https://www.inaturalist.org/projects/eggs-nests-n-america
https://www.inaturalist.org/projects/eggs-and-nests
https://www.inaturalist.org/projects/bird-nests-of-north-america

Third and last problem I've encountered. Inviable eggs does not count as an "active" nest. So if you make an observation of an inviable (dead or unhatched) egg, such as Tree Swallow, in a Minnesota December, it does not meet project requirements because it's not active. That's because Tree Swallows appear to be a very strict May-July breeder and eggs hatch in about 14-17 days. They'll migrate out of Minnesota in September, so if that egg in December was going to hatch, it would've hatched long before then. Any observations that show probable inviable eggs will be removed from the project.

That's all the problems I've encountered and all of these observations that fail to meet project requirements will affect the data I'm trying to collect. Your diligence in following these requests are greatly appreciated. For those who haven't joined the project yet will now have additional "Terms and Rules" to agree to when they join. Before now, I only had the rule that you agree to follow the Code of Conduct in watching bird nests. The terms are now as followed:

"By joining this project, you agree to follow the protocols presented in the "Code of Conduct" presented by Cornell's NestWatch project, to maximize the chances of a successful nesting attempt. To read the Code of Conduct:

https://nestwatch.org/learn/how-to-nestwatch/code-of-conduct/

All observations added must be Aves (Birds) and be an active nest. Meaning parents building/fixing nest, eggs or young in nest. Inviable (dead) eggs or deceased young do not meet project requirements."

Once again, I thank you for joining the project and I hope my attitude in this post hasn't deterred you from your contributions to the project. I just want to make sure the project continues down the course it was meant to follow, otherwise it would be no different than the projects I've listed above. Thank you for understanding.