Perle was standing on one leg just like all other birds. The question was if something was wrong with her other leg.
Birds standing on one leg: mechanisms and meaning
Why is a birds standing on one leg ....... experiments showed that the body remains quite stable when simulating a one leg stance with an adducted leg wheras it becomes
unstable when simulating a two-leg stance with the leg aligned vertically . This means that the one leg stance seems to be very stable mechanically and thus probably needs few muscular activity.
.....Reduction of muscle fatigue of the retracted leg.
Humans tend to put the body weight on one leg when standing for longer times. This serves to reduce muscle fatigue in one leg. Accordingly, Clark (1973) suggested that standing on one leg in birds may serve a similar function. However, retraction of one leg needs muscle activity. This is confirmed by an own observation of a resting nile goose (Alopochen aegyptiacus) whose retracted leg dropped again and again. However, when sleeping with its head on the back and with closed eyes, the leg was continuously hidden in the plumage. That leg retraction needs energy is supported by the casual own observation of a woolly-necked stork who fixed his retracted foot to the intertarsal joint of the stance leg (Fig. 12). There is no indication of structural or physiological mechanisms which may reduce muscle activity in the retracted leg as already noted by Clark (1973). During flight legs are retracted in a similar way as one leg during the unipedal stance. In a biochemical study it was shown that leg muscles involved in flight posture do not have specializations (McFarland & Meyers 2008). However, one has to consider that hindlimb muscles of birds are close to the body (normally hidden in the plumage) which reduces the energy to lift the leg.
Conclusions
Most birds stand or sleep on one leg without having specializations in their legs. The leg is positioned in such a way that the body is well balanced without much additional muscle activity. Most long-legged birds like flamingos and storks have specializations in the hip joint and intertarsal joint which help stabilizing a body which is far from the ground. So far an often cited snapping mechanism has been demonstrated convincingly only in the ostrich, a long-legged bird who does not stand on one leg. Whether there is a similar mechanism in long-legged birds standing on one leg is unclear. It seems that the extra-labyrinthine sense organ of equilibrium in the lumbosacral vertebral canal plays an important role in keeping balance when standing on one leg. This sense organ may even be a prerequisite for easily standing on one leg.
A useful function of standing on one foot with hiding the non-feathered part in the plumage is to reduce heat loss. Such a function is supported by recent quantitative behavioral observations. As to standing on one foot while preening or without hiding one foot in the plumage one might argue that the ability to stand easily on one foot is used even when there is no need for a reduction in heat loss, i.e. thermoregulation is probably an important but perhaps not the only function of standing on one leg. For another possible function discussed in detail, the reduction of muscle fatigue, there is so far no experimental support. The recent discovery in flamingos that standing on one leg results in a more stable body position than standing on both legs (see above: Functional anatomy/Standing on one leg) seems to be an attractive explanation why most birds prefer to rest on one leg independent of other functional implications like e.g. a role in temperature regulation.
18:53:17 Anna arrives with a mouse and Perle the magician made it disappear in a flash.
Just after 19:00 Anna returns with spruce sprig. This led to the moment captured by Pascale.
Anna left ...
Liz01 - when does the eye colour change? I really noticed it in the screen shot. yellow vs very dark.
21:02 Anna in with green bedding. She left again 21:03:24, flying to a spruce just visible to the right of the right hand trunk. back to nest 21:05:10 with a rather sparse twig.
Mom and chick time until 21:59 when Anna closed her eyes ZZZZZZ
Comparing Perle and Anna's primaries, Perle has a way to go to achieve full feather length.
Perle swallowed it 
