7. (10 points) In the zoo, there are several ostriches and deer. Together, they have 122 legs. If the number of ostriches and deer were swapped, they would have 106 legs. Therefore, there are $\qquad$ ostriches and $\qquad$ deer.
【Analysis】A sika deer has 4 legs, an ostrich has 2 legs. Replacing an ostrich with a sika deer results in 4 - 2 = 2 fewer legs. Swapping all ostriches and sika deer results in 122 - 106 = 16 fewer legs, which means 16 ÷ 2 = 8 sika deer were replaced with ostriches, so originally there were 8 more sika deer than ostriches. Adding 8 more ostriches makes the number of sika deer and ostriches equal. Therefore, adding 8 × 2 = 16 legs, the total number of legs becomes 122 + 16 = 138, at which point the number of sika deer and ostriches is the same. At this point, one sika deer and one ostrich have 4 + 2 = 6 legs, which can be used to find the number of sika deer, and thus the number of ostriches.

【Solution】122 - 106 = 16 (legs)
$$
\begin{array}{l} 
16 \div (4 - 2) \\
= 16 \div 2 \\
= 8 \text{ (heads) } \\
(122 + 8 \times 2) \div (4 + 2) \\
= (122 + 16) \div 6 \\
= 138 \div 6 \\
= 23 \text{ (heads) } \\
23 - 8 = 15 \text{ (heads) }
\end{array}
$$

Answer: There are 15 ostriches and 23 sika deer.
The answer is: 15, 23.