Something is wrong with Hugo my American Buff gander

[GermanChick]

I have two pair of American Buff, almost 5 month old. Hugo, who is the biggest of the two male and kinda the alpha seems to be "off" since yesterday. They are in a big fenced in orchard/pasture with 7 ducks and since yesterday he mostly just lays in the grass. He doesn't come to the fence when I walk by like all the others and like he used to do. He follows the others if they are too far away but even then he seems to walk slower than usual. He just looks tired and exhausted. There is nothing obvious wrong, no injuries, no limping or anything like that. He eats and drinks. I just have a feeling that something is wrong with him judging from his behavior. He was always the first one to run at the fence and now he just lays around and is not interested in anything :-( What can I do to figure out what's wrong?????

Thanks,

 

[GermanChick]

Here are some pictures. I know it is hard to diagnose without any obvious symptoms but I am just worried about him. He is just not himself :-(

Didn't know I was so attached to my geese/ducks. I like my chickens but I LOVE my geese/ducks!

 

[Miss Lydia]

Here are some pictures. I know it is hard to diagnose without any obvious symptoms but I am just worried about him. He is just not himself :-(

Didn't know I was so attached to my geese/ducks. I like my chickens but I LOVE my geese/ducks!

It's so hard to know sometimes what could be wrong especially if if there is no obvious symptoms., could he have gotten into something toxic plants, something rotting? you might try a flush on him to see. I'll get you the link on flushes .
https://www.backyardchickens.com/t/700526/flushes-for-aiding-in-toxin-removal#post_9508213 gorgeous geese and ducks