Extremely interesting study of birds in the Chernobyl region

This study was posted onENENews. Some excerpts:
"First, we know that populations in contaminated areas are maintained through immigration from source populations, because local reproduction and survival are insufficient for maintenance of stable populations [30]
"Second, we have shown reduced adult survival rates [6; this study] and reproductive rates [6], [11] in contaminated areas. Age ratios for birds at normal and high background radiation levels differed considerably from an average of 43% at normal levels to an average of 73% at high levels. This observed difference in age ratios between control and contaminated areas implies an increase in the frequency of juveniles from 43% to 73%, or an increase by 30% (73% – 43%). Given that the area contaminated by more than 0.05 µSv/h exceeds 30,000 km2 (Fig. 1; [31]), and given that the typical population density of breeding birds exceeds 100 pairs per km2 [24], this implies an annual excess mortality of 30,000 km2 × 100 pairs/km2 × 0.3 = 1.8 million birds. These findings also imply that the magnitude of this ecological sink is likely to exceed that of any other sinks described in the literature (review in [32]). Therefore, the findings reported here also have significant conservation consequences caused by the Chernobyl disaster. Finally, skewed sex ratios may increase the risk of local extinction for demographic reasons [33], [34].

What it seems they are saying is that birds are not actually surviving in the area except through the continual arrival of new birds from outside. In other words, if no new birds flew into the region then birds would cease to exist. And the new birds have seriously reduced life expectancies!
I am wondering about the implications for Japan where nearly half of their country and their population has been directly contaminated and the rest of the country is slowly being exposed through weather, foods and travel.

http://enenews.com/study-increases-in-the-frequency-of-selective-deaths-...