Habitat sinks can attract dispersing animals if high mortality or breeding
failure are difficult to detect (e.g., when due to human hunting or polluti
on). Using a simple deterministic model, we explore the dynamics of such so
urce-sink systems considering three scenarios: an avoided sink, no habitat
preference, and an attractive sink. In the second two scenarios, there is a
threshold proportion of sink habitat above which the whole population decr
eases to extinction, but this extinction threshold varies with habitat pref
erence and the relative qualities of the two habitat types. Hence, it would
be necessary to know the habitat preferences of any species in a source-si
nk system to interpret data on population increases and declines. In the at
tractive sink scenario, small changes in the proportion of sink habitat may
have disproportionate effects on the population persistence. Also, small c
hanges in growth rates at the source and the sink severely affect the thres
hold and the time of extinction. For some combinations of demographic param
eters and proportion of habitat sink, the decline affects the source first;
thus, during some time, it will be hidden to population monitoring at the
sink, where numbers can even increase. The extinction threshold is also ver
y sensitive to the initial population sizes relative to carrying capacity.
Attractive sinks represent a novel aspect of source-sink dynamics with impo
rtant conservation and management implications.