32khz crystal for AVR. Caps needed?
Atmel says  Crystals specifying load capacitance (CL) higher than 6 pF, require external capacitors applied as described in
Figure 9-2 on page 38.

6pF Xtals do exist but will not be as stable unless your layout includes a ground plane under the XTAL to create this added capacitance, the tolerance of the crystal cannot be met. But 50 ~100 ppm error may be close enough for you.

With no ground plane under the tracks or Xtal there is much less stray capacitance.

A Saturn PCB design simulation (free) can prove a layout capacitance  if you really want to eliminate the caps.

0.127mm 1oz tracks over 0.127 thick FR4 is 0.92 pF/mm so 6.5mm track length would give 6pF on each track. Cin on chip is &lt;1pF.