Yep! Here's the picture to prove it!
Actually I'm a bored artist and I couldn't resist illustration this. I will be making a few more on comments like this if the illustrations are liked, as a thankyou to duolingo for helping me learn Danish and improve other languages I already know.
I'm not a native Danish speaker, but the "D" can sometimes sound like an English "D", like in "dyr" and "det". Other times, though, it does seem to sound like an "L", as exhibited in "skildpadde" and "mad". I don't know if there's a rule about how to pronounce it, it may be by memory. :)
I'm learning Norwegian since september at university and my teacher said that most of the time you don't pronounce the "d" at the end of words and you don't pronounce the "d" depending of the letters that precede or that follow it. For example in "med" the d is silent. And you don't pronounce it either in words that contain a word where the "d" is silent like in "utlendinger" which means something like "outsider". I think it may be linked as Norwegian and Danish are pretty close (at least when you write them).
I'm sorry if I wasn't really clear, it's just an idea and my teacher said there was no really specific rule for this. And sorry for bad English, it's not my native language and it's not so easy to explain something in Norwegian while not speaking in my everyday language ^^
Your impression is pretty accurate I would say. At the beginning it's like a regular D. In the 'nd' combination it is silent, as in hund or kvinde, etc, but otherwise, such as between vowels and at the end, it's more like a semistretched out L than anything else.
When in doubt I also wanted to mention again that on www.forvo.com you can listen to native speakers speak most words of Danish and a ton of other languages, whenever there's any doubt. Hope that helps!