Department of Physics, Chemistry and Biology (IFM)

The most important factor for a successful reintroduction is whether it is a producer- or consumer species (fig. 2). There are varying results in reintroduction success and secondary extinctions caused by reintroductions depending on trophic level when increasing the change in the reintroduced species. The following tables are based on Christanou & Ebenmans (2006) four different outcomes.

If you compare the probability of reintroduction failure without any secondary extinctions you can see that there is a clear difference between basal (producer) species and intermediate/ top predator (consumer) species presented in the tables below;

Table 1. Basal species: Four different outcome). The four outcomes when reintroducing a species; I= failure without causing any secondary extinctions, II=failure with secondary extinctions, III=success without secondary extinctions, IV=success with secondary extinctions. This table is based both connectances with 6000 reintroduction attempts.

As stated earlier, the basal species has a harder time to come back into the food-web when it is reintroduced with changed growth-rate. This leads to less secondary extinction, since they cannot come back into the ecosystem again causing the rapid increase in case I (table 1).

Table 2. Intermediate species. The four outcomes when reintroducing a species; I= failure without causing any secondary extinctions, II=failure with secondary extinctions, III=success without secondary extinctions, IV=success with secondary extinctions. This table is based both connectances with 4800 reintroduction attempts.

Since the intermediate and top predator species (table 2 and 3) do not have the direct interspecific competition as basal species has, they are more likely to have a successful reintroduction without any secondary extinctions. Further there is a difference how the consumer species reacts to changed attributes compared to producer species, the effects exists but not as dramatic as in basal species. The data also indicate that there are less secondary extinctions when reintroducing a consumer species then when reintroducing a producer species..

Table 3. The four outcomes when reintroducing a species, Top predator species; I= failure without causing any secondary extinctions, II=failure with secondary extinctions, III=success without secondary extinctions, IV=success with secondary extinctions. This table is based both connectances with 3600 reintroduction attempts.