The phrase "increased migration" refers to a situation where more people are moving from one place to another, usually to live in a different country or region. Full definition
This process increases the migration of white blood cells, which in turn strengthens your immune system. (mindbodygreen.com)
After several hours, the oil had also softened the chocolate, leading to increased migration of the fat. (sciencemag.org)
Projects are already in the works to build channels from sources in the sparsely populated but water - rich Amazon basin, while tropical regions are seeing increased migration from the highlands. (scientificamerican.com)