However , the presence of German submarines made the trips too risky and the group switched to homing pigeons .
Lishansky swam ashore to collect Nili information and to pass money sent by American Jews to the starving yishuv .
The presence of German submarines made the trips too risky and the group switched to homing pigeons .
Lishansky swam ashore to collect Nili information and to pass money sent by American Jews to the starving yishuv .