Northern Prairie Wildlife Research Center
Fledging rate is the most important measure of plover reproductive success because it represents a direct link to recruitment.
Investigators can use some of the same techniques described for nest-finding, especially remote observation. These are the best overall approaches in terms of efficiency and minimal disturbance.
However, avoid walking on alkali nesting beaches to count young plovers, given the risk of stepping on chicks that typically respond to alarm calls of adults by lying motionless. And plover chicks that move into adjoining territories to elude an investigator may be aggressively attacked by defending adults (Haig 1992; B. Root and K. Smith, pers obs). These are less serious concerns with older (> 14 days old) chicks.
Allow ≥ 1 hr of observation, under good conditions (cool [< 25 C/< 75 F], calm to light wind [< 30 kmph/< 20 mph], no precipitation) to account for all chicks that could be present. If no young are observed, ≥ 1 additional observation visit should be made in < 1 wk, preferably within 2-4 days.
It is helpful to locate adult plovers and observe them closely to find chicks, which stay within 10-20 m and are brooded often when up to 10-14 days old. Alternatively, behavior or absence of adults may corroborate suspected chick loss. A breeding pair that has lost its chicks usually will spend its time quietly preening, resting, and feeding, and appear indifferent toward trespassing conspecifics. In < 1 wk the adults may abandon the territory. On the other hand, adults with young will remain alert and persistently defend their territory although the female may leave before chicks fledge (Haig and Oring 1988, MacIvor 1990).
Plover chicks on alkali lakes typically remain within 50-100 m of their nests when < 10 days old, and often longer. They sometimes roost in the shade of large rocks on hot days or use sparse, grassy vegetation as escape or thermal cover (B. Root, unpubl data). Older chicks tend to travel farther, especially when adjoining territories are unoccupied.
For example, isolated breeding pairs with 14-day-old chicks have been observed > 600 m from their nests (Whyte 1985; R. Murphy, pers obs), and older young may mover farther to feed at mudflats or islands created by exposed gravel bars. Therefore, all potential nesting and foraging habitat should be searched, within reason.
Uniform vegetation such as dense sedges and grasses usually hinders movement of plover chicks along alkali lakeshores, as might territory occupancy by other plover families. Counts of plover chicks can be particularly difficult in areas of concentrated nesting, although young of various breeding pairs usually can be separated by relative age, brood size, and territory affinity.
Still, it may be most practical to simply count total numbers of young and breeding pairs in such situations.