Comment on Stallion WordPress SEO Plugin by SEO Dave.
The problem is there’s a fair number of plugins (and some themes) which add their own canonical URLs and the webmaster needs to choose which one to use: if that’s possible, each plugin is different, some can’t be disabled.
For example these plugins tend to disable the built in WordPress canonicals (WordPress by default has canonical support).
Stallion WordPress SEO Plugin – Disables WordPress Core Canonical Support When Required
Yoast WordPress SEO Plugin – Disables ALL WordPress Core Canonical Support
All In One SEO Plugin – Disables ALL WordPress Core Canonical Support
Project Supremacy Plugin (according to your comment)
The Stallion SEO plugin has code to disable the canonicals from Yoast and All In One when the Stallion canonicals are created, otherwise there would be duplicate canonicals similar to your current issue. Assuming the Project Supremacy SEO Plugin is adding the Author archive canonicals (my guess is it’s a plugin bug that they are loaded on Author archives) your choice is disable the Project Supremacy canonicals or the Stallion canonicals: to disable the Stallion canonical tick “Index All Author Archives” and Stallion reverts to core WordPress behavior on Author archives.
Currently your canonicals don’t make sense.
The Stallion WordPress SEO Plugin overrides the WordPress core canonical support when the canonical output is different to the WordPress core canonicals.
For example on the Author Archive Pages if you’ve ticked the Stallion plugin option “Index First Author Archives Only : Block Paged 2,3,4…” (which you have ticked) on the Author Archives ALL pages will have the same canonical so only one of the webpages are indexed.
So these pages will all have identical Stallion canonicals:
They all have a canonical to /author/david_contributor/, this tells Google to spider them all, BUT only index the first page (the one set as the canonical). The SEO benefit of this is link benefit and SEO benefit from pages 2,3,4 etc… is partially recovered (we loose ~15% of the link benefit via a canonical URL) and concentrated on to the first page. With these types of archives there’s no point having pages 2,3,4 indexed, they won’t rank for anything, so makes sense to recover most of the link/SEO benefit via a canonical URL.
So you have a good Stallion plugin setting IF you want the Author archives indexed.
Looking at the output of your Author archives they are showing one Post per page, so the content is almost identical to the one Post shown: not ideal SEO wise or user friendliness.
You have a similar output on Categories and Tags, you’ve presumably set “Settings” > “Reading” : “Blog pages show at most” to 1. This is not a good idea SEO wise, I’d suggest setting to at least 5, so up to 5 Posts load on each archive output.
You have something weird going on with either a plugin or the theme because a canonical to a Post on an Author Archive isn’t default WordPress behavior (Project Supremacy SEO Plugin bug maybe).
On Category archives no canonicals are added : nothing wrong with this it’s core WordPress output (you don’t NEED a canonical on every page).
On Tag archives no canonicals are added : nothing wrong with this it’s core WordPress output.
On Author archives the canonical points to the one Post shown : with the one Post per page output this does sort of make sense, the author archives are sort of a duplicate of the Posts. Not how I’d do it, every time you add a new Post the canonical URL on these change because the Post loaded changes:
Today the above canonicals point to:
/author/david_contributor/ – URL Of Post Three
/author/david_contributor/page/2/ – URL Of Post Two
/author/david_contributor/page/3/ – URL Of Post One
Add a new Post tomorrow and they change to:
/author/david_contributor/ – URL Of Post Four
/author/david_contributor/page/2/ – URL Of Post Three
/author/david_contributor/page/3/ – URL Of Post Two
Add another Post and they change again and again and again…
That is not how to use canonical URLs, if you’ve been advised to setup your site this way, whoever gave you that advice doesn’t understand how Google works on passing SEO value through canonical URLs. Canonical URLs are like soft 301 redirects and shouldn’t be changed regularly.
Add to this the Category and Tags have a similar output to the Author archives, but lack the canonicals to the one Post loaded. Ignoring the Stallion plugin canonicals right now you have pretty much duplicate category/tag/author archive output and the author archive canonical is informing Google the author archives are a duplicate of the one Post loaded, so only index the Post. But also index the duplicate category and tag output! Doesn’t make sense SEO wise.
If a Post is added to 2 categories and 3 tags it’s duplicated at least 6 times (the 6th is the Author archive), but only one of the duplicates has a canonical to the one Post. Right now all your categories, tags and author archives are a waste of SEO space, they add no SEO value to the site (aren’t even user friendly) AND wastes link benefit: even if you got your canonicals right for the one Post setup (all your archives having the canonical pointing to the one Post loaded: which is a bad idea, see earlier) it still costs link benefit having 6 versions of the same content spidered (each canonical costs ~15% of that pages link benefit).
If it were my site I’d dump the Author archives completely (might require modifying the theme to remove the author archive links: Stallion Responsive for example has the option to hide the links) and the tags completely (simply delete all the tags) and limit each Post to 2 categories (unless there’s a good reason for more than 2).
Set “Settings” > “Reading” : “Blog pages show at most” to at least 5 (set higher to limit wasted link benefit) and allow the Categories to either be fully indexed or index first page only (Stallion options “Index All Categories^^” or “Index First Categories Only : Block Paged 2,3,4…^^”).
This will limit the number of archives to a minimum, having Posts added to two categories is more than enough to keep Posts spidered/indexed etc… since you’ll have far fewer archives allowing more link benefit to flow to your important content (your Posts). Every webpage that’s linked to costs link benefit even if you use canonical URLs to recover the link benefit (can’t recover it all), so if a webpage has no value (Author Archives and Dated Archives for example) get rid of them (don’t link to them).
BTW I noticed on Posts (view the HTML source of a Post) the Project Supremacy Plugin is adding meta description tags, meta keywords tags and meta robots tags (the meta keywords tags are ignored by Google, the robots output is default behavior and so aren’t needed) listed under “Open Graph Data Supplied By Project Supremacy”. Those three meta tags aren’t Open Graph Data (there’s no Open Graph Data on the Posts I viewed), so might be a case of the plugin developers don’t know what they are doing (or they’ve labeled it badly).
You also have “Google Site Verification by Project Supremacy” on every page (only needed on the Home page), once you’ve verified a site with Google you can safely remove that code, the Google verification code is also added twice (maybe the theme adds it as well?). In Stallion Responsive for example the Google verification code only loads on the home page and I have it set so on each theme update that and similar one time verification meta tags are emptied. It’s a minor issue, but removing unnecessary features is a positive for SEO performance, sites load faster.