A complete waste of time, especially for birders. The observatory is more of an architectecural oddity, replete with ample photos on the observation deck of other notable Kushiro buildings. Nice, if second rate hobby architecture is your thing. Those looking for information or views regarding nature, however, may feel as I did — swindled.
After paying 1380¥ for the round trip bus and 480¥ admission, they charge an additional ¥200 to use the binos on the observation level. Really? I had my own, and certainly needed them to see the significant distance off to the marshes. Had there been cranes (no fault of the observatory, simply the wrong time of year), I would have been hard-pressed to to see anything, even with my 10x42s. As it was, all I could see were 5 crows about 400-500 meters out: alert the press.
The exhibit level is a pathetic managerie of sub-wiki-level exhibits. I wish someone had warned me it was such a waste of time!
The boardwalk (no entry fee) is nice, but certainly not as good as Harutori Park, conveniently located in town. The boardwalk yielded 6 species on the one hour 2.5 k loop, while Harutori Park the day before (similar weather) yielded 19 species in 2 hours on its 4+ km circumference.
Maybe kids are somehow mesmerized by the exhibits, but I doubt it. On top of the dry (largely Japanese-only) explanations and the what-can-we-scrape-together-to-fill-this-space exhibits, the exhibit level is kinda dark and creepy (it is quite possible they forgot to turn the lights for us, the only two visitors at that time?), so my guess is children lose interest in a wink.
In short, don’t bother.