Individual Results in Form Discrimination Experiments

Nest 1. Redstart.
In the process of training the birds were offered to discriminate a vertical gray/green grid (reinforced by access to the nestlings) from a horizontal one. Both female and male redstarts learned to discriminate the grid orientation.
The female easily accepted the change of the stimuli for grids metameric for human observer and continued to discriminate their orientation correctly (see the table below). In the first test session the male showed its anxiety (uttered cries of alarm, flitted from one stimuli to the other, that is typical for the behavior of birds after a considerable change of the experimental conditions, specifically, the color of the stimuli). But the next day the male easily discriminated the metameric grids by their orientation with high confidence.
To prove the hypothesis that its initial fear was provoked by the change in grids color but not by the inability to determine their orientation we presented black/white grids in a following session (not shown at the table). Again, the male was afraid and did not visited the entrances at all, whereas the female easily made right choices with score 10:0.

Experimental conditions and discrimination scores
(the number of choices of the stimuli)
for female and male redstarts from the nest 1
last training session first test session second test session
+
vertical
gray/green
grid
-
horizontal
gray/green
grid
+
vertical
metameric
grid
-
horizontal
metameric
grid
+
vertical
metameric
grid
-
horizontal
metameric
grid
 
20 : 10
 
13 :  2
 
40 : 22
 
10 :  3
 
 6 :  4
 
20 :  2
Nest 2. Great tit.
The same task with gray/green grids proved to be difficult for this pair of birds. The male did not learn at all and held the position strategy (visited mainly the left entrance) during all 6 days of the experiment. The female seemed to combine a left-hand and a grid orientation-dependent strategies even at the end of training. The change of the stimuli for black/white grids frightened it.
Nest 3. Flycatcher.
The discrimination of metameric grids proved to be an easy task for the female. It learned to distinguish a vertical metameric grid from a horizontal one in one day, correctly recognized the grid orientation when tested with gray/green grids and then discriminated different specimens of metameric grids with confidence in test sessions during next 3 days of the experiment.
The male from this nest practically did not take part in feeding the nestlings.

Experimental conditions and discrimination scores
for female flycatcher from the nest 3
last training session first test session second test session
+
vertical
metameric
grid
-
horizontal
metameric
grid
+
vertical
gray/green
grid
-
horizontal
gray/green
grid
+
vertical
metameric
grid
-
horizontal
metameric
grid
 
18 :  4
 
14 :  5
 
43 : 25
Nest 4. Great tit.
Only the female learned more or less to discriminate metameric grids. But it never used a perch for viewing the stimuli and made many mistakes. So, to get reliable figures one had to acccumulate many trials from several sessions. For this reason it was decided to terminate testing and switch to the task of color recognition.

Experimental conditions and discrimination scores
for female great tit from the nest 4
training sessions test sessions
+
vertical
metameric
grid
-
horizontal
metameric
grid
+
vertical
metameric
grid
-
horizontal
metameric
grid
 
23 : 12
 
30 : 16
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