Factually is a correct word, but I prefer in fact as the expression. it does not change the meaning. Why do you mention animal migration? Animal migration is common in some regions. I think the topic is not relevant, but it is safe to disagree. The phrase for example is correct, regardless of the number of examples. Not all adverbs in in ly. First is an introductory adverb. Introductory words and phrases are not required to be ly words. For example, First, Second , these are all introductory words or phrases, and function as adverbs. Fearing of their lives means same as I fear my life. Fearing for their lives means same as I protect my life. People who travel for pleasure and enjoyment are tourists, not migrants. Immigration procedure uses this term, but I think it is right in migratory patterns too.
Last, I think your last paragraph on animal migration is weak. The grammar is now correct, but consider the intent. Do you want to say this is bad or good effect ? Can you give examples to show it? Please think of how you organize the paragraph.
In fact, people are on the move all the time. People decide to migrate for simple or complex reasons, and it can occur as a result of push and pull factors. They may be moving voluntarily or compulsorily, and it can be permanent or temporary. The movement of people can be internal or external migration. Internal migration is the movement of people inside the country. External migration is the movement of people outside the country, which can be called international migration or emigration. Migration has an impact on the native land of the migrant, and also on their destination. These impacts can be both positive and negative. Actually, not only humans are moving, animals too, and itís called animal migration. But itís not as common.
There are many reasons why people are moving, and some of the reasons are really common. For example, there are natural disasters, better living conditions, job opportunities, poverty, war, and so on. In fact, there are quite a lot of strong reasons why they are leaving their country. First, it can be of fearing for their lives, because of religious or ethnic persecution. For instance, in Indonesia, a long time ago, there were many Chinese people moving to Indonesia in order to find better living conditions.They stayed up there,and started creating big families, and kept increasing until now. In the mean time, the ratio of Chinese people in Indonesia is only 3% of the population. Unfortunately, there are some Chinese-Indonesians trying to move to another country because of the religious and ethnic persecution. They feel that living in Indonesia makes them feel afraid. Truly, some Indonesians donít like Chinese people. Moreover, Indonesians think that all the Chinese who live in Indonesia are rich, and actually it is not always true. Some Chinese are also poor and some of their lives may be uglier than the native Indonesians' lives. In this case, it would be a push factor.
Second, family links are a reason why people move. As I mentioned above, it could be that the one who moves to Indonesia has families in China. Hence, they maybe felt lonely and worthless without their families. As a result, they may be moving back to their native country in order to get together with their families. In this case, it would be a pull factor. Another example is, when a person moves to another country to find a better job, he/she would get homesick and probably move back to his/her native country.
Third, there is the enjoyment. Some people who are rich enough, they move to a developed country to live for the entire of their life. They think spending their time in a developed country would be much more enjoyable rather than staying in a developing country. With good economic, political, and environmental conditions, they might live happily. Moreover, they are rich, so they can do anything they want. In addition, with better education, living conditions, medical treatment and technologies, they will get high satisfaction. Therefore, their children and grandchildren may also stay there until they find another better place to live. There are many developed countries which are really popular places to live, such as Australia, America, Europe, Japan, etc. In this case, it would be a pull factor. However, there are people who only travel for holidays or vacation. They may go temporarily to find a satisfaction or enjoyment. Usually itís influenced by seasons change.
There are also impacts due to the movement of people. One of those is the change of the population in both the migrants' home country and their destination country. This may change the population, and could also bring bad effects to both the countries. The population in the country they left will decline, which lead to an increase of job vacancies. Besides, the destination country the population increased. This may lead to bad problems, such as, unemployment, crimes, overcrowding, etc. With many jobless people, they would do anything in order to get money; in this case, the level of crimes will rise. Since there are many people in the area, the number of people will increase and be overcrowded. Apart from it, there is also a mixing of different cultures and races, which may lead to negative social behaviors and tensions in society between majorities and minorities, followed often by local struggles and racism and racial discrimination. There are also some positive cultural effects of migration, for example exchange of cultural experience, new knowledge and so on. It may bring a good economical condition, for instance, if the country is lacking of workers, the comers will be the workers for them and itís benefiting to both of them. The firms get more workers and the migrants get a job.
Lastly, migration can be also animal migration, where animals are being moved around the world. By doing this, all different types of animals in the world are being mixed and combined with each other. Hopefully, it might create something new. However, some animals are not really stable in some seasons or conditions. Therefore, animals like penguins are usually live in the cold locations, for instance, Antarctica. For some reasons, some of them are being brought for an experimental thing like cloning.
In conclusion, I think outward migration usually happens in developing countries, where people are moving to any developed countries to find better living conditions and security. But sometimes, people in developed countries are also moving to any developing countries in order to have a low cost of living. Most of the factors happening in developing countries are like lack of jobs, wars, crimes and poverty. And in developed countries, the factors are usually something like high cost of living. In my opinion, I think migration is a good way to mix people by races, religious, cultures, education, and even backgrounds. But sometimes it may also destroy the countriesí cultures and may create conflicts between those differences.