1981] Mac Kay— Nest Phenologies of Pogonomyrmex 
27 
such a method would only estimate the numbers of foragers in a 
Pogonomyrmex nest, not the actual nest population. In addition, 
mark-recapture methods do not provide an estimate of the repro- 
ductives produced in a nest. 
Excavation of nests destroys them for further study and requires a 
large expenditure of time and effort. I chose periodic nest excava- 
tion as the method of estimating production as counts of the 
sexuals, brood, and workers can be made. 
Our experience indicates that most of the nest population is 
collected. Pogonomyrmex spp. colonies may live 15 to 20 years 
(Barnes and Nearney 1953), and will live at least two years after the 
removal of the queen (pers. obs.). Nest longevity is unknown in the 
three species investigated, but based on data from other species, I 
expect at least 5%rl0% of the nests should not have queens. The 
high proportion of nest queens collected (84% in P. montanus, 77% 
in P. subnitidus, and 80% in P. rugosus ) supports the hypothesis 
that most of the nest population is collected. The queens do not 
reside in any special “queen chamber” and are of a similar size as a 
worker. Therefore, it is not any easier to find the queen than it is to 
find any individual worker in the nest. In all cases excavation was 
continued at least 50 cm deeper than the position of the last ant 
found or the end of a burrow. 
Nest excavation procedure. 
The procedure was as follows: The surface dimensions of the nest 
were determined by removal of the top 10 cm of the nest. The hole 
was then extended at least 50 cm on all sides. A square ditch was 
dug around the perimeter of the nest to a depth of one meter in the 
case of P. montanus nests and over 1.5 meters around the nests of P. 
rugosus and P. subnitidus. We were able to sit in the ditches while 
carefully excavating the nests in 10 cm levels. As the hole became 
deeper, the ditches were proportionally deepened. All of the 
contents of the burrows, including ants, brood, guests, stored seeds, 
and dirt were placed in labeled half or one liter plastic containers. 
Later the animals were separated from the dirt, and counted. Nest 
excavation usually began between 06:00 and 07:00, before the ants 
became active. If foragers were needed for other investigations, 
excavation began later in the morning or early in the afternoon. 
Excavation and counting of a P. montanus nest requires 6-10 hours, 
of a P. subnitidus nest 20-30 hours and of a P. rugosus nest 60-90 
