Conservation and Management

Shooting And Trapping

Occasional shooting by aquaculture staff and vandals at various locations in se. U.S., and in West Indies, plus occasional egging (Blus et al. 1979, PAB/FGB), neither of which now at levels adversely affecting even local populations.

Contaminants

Blus et al. (1979) reported extensive examination of boreal S. m. maxima from S. Carolina for a variety of contaminants, none regarded as threatening to its breeding population. Ranges of residues (µg/g wet weight) in 227 eggs collected 1970–1975 included: DDE, 2.36–4.13; DDD, 0.14–0.35; Dieldrin, 0.07–0.83; Mirex, 0.19–0.92; Toxaphene, 0.43–0.73; cis -chlordane, 0.12–0.35; CNCH, 0.19–0.21; trans -nonachlor, 0.76–0.78; oxychlordane, 0.15–0.33; heptachlor epoxide, 0.11–0.17; PCBs, 2.77–9.50; total Hg residues, 0.70–1.30 (10 eggs; 1970 only). Same study also confirmed that eggshells had increased in thickness from pre-1947 to study period.

King et al. (1983) examined eggs from boreal S. m. maxima colonies on Texas coast collected in 1970 and 1978 (n = 45), with following ranges of mean residues (ppm): DDE, 1.13–4.28; PCBs, 0.75–11.60; and of heavy metals in 1978 only (n = 30), Zn, 11.72–12.32; Hg, 1.11–1.27; Cu, 1.09–1.22; Se, 0.94–1.06; and As, 0.13–0.18. Here too eggshell thickness increased, but in period 1970–1978. Pre-1947 eggs did not differ overall from post-1947 eggs. These contaminant values likewise regarded as unthreatening to Texas population. No anatomical deformities reported in any Royal Tern population.

Maness and Emslie (2001) examined breeding boreal S. m. maxima in N. Carolina for evidence of genootoxic (DNA-damaging) exposure, finding significantly higher levels of DNA damage in birds at 2 particular colonies than elsewhere, but were unable to correlate them with contaminant levels in immediate-area sediments.

Ingestion Of Plastics, Lead, Etc

No information.

Collisions

No information.

Fishing Nets/Lines

Buckley and Buckley (1974) analyzed 1,222 boreal S. m. maxima banding recoveries through 1970, finding 274 whose cause of recovery listed as having been captured by, or entangled in, fishing lines or hooks. Of these, 18 >2 yr old, 15 >1 yr old, but some 241 <1 yr old. This corollary to juveniles’ undeveloped fishing skills illustrates clearly ways in which juveniles are at risk in first year of life.

Degradation Of Habitat

Development of barrier islands and other sandy, remote, quadruped-free sites has forced boreal S. m. maxima to rely on handy and numerous alternative: dredge-spoil islands. Significant proportion of U.S. S. m. maxima population resorts to them, and so long as available, predator-free, and have fresh clean sediment deposited at sufficient intervals to keep them in early-successional stages, problems unlikely to arise (Buckley and Buckley 1975, Soots and Parnell 1975, Parnell and Shields 1990). However, S. Emslie (pers. comm.) reports that with recent cessation of sediment deposition on N. Carolina spoil islands, grass now covers many formerly bare areas. Surprisingly, Royal Terns still use them, but uncertain for how long. Unlikely that winter habitat significantly degraded in any areas we know of.

Disturbance At Nest And Roost Sites

Human disturbance at boreal S. m. maxima colonies local and episodic, but probably not even close to systemically severe. Chief culprits are thoughtless boaters, jet-skiers, picnickers, fishermen, and swimmers (especially any with dogs), although most find din and smell of large, active colony off-putting and quickly depart. Particularly in Caribbean, but also elsewhere, subsistence egging still practiced by few people, but again probably not at scale damaging to any population. We have not yet seen all-terrain vehicles on any spoil islands, nor have we encountered personal hovercraft, but these surely among future scourges. Austral S. m. maxima chicks killed by gulls in Argentina when forced from colonies by tourists (Escalante 1985). Here, terns nest directly on exposed, unprotected beaches easily accessed (in 1980s) by many tourists annually, who often arrive by boat with pets. Escalante also believed that raw sewage, chemicals discharged into marine waters, and oil spills from ships, also adversely affecting austral S. m. maxima and other seabirds, especially those breeding within Rio Plata plume.

Direct Human/Research Impacts

Not studied, but reports of chick mortality following mass banding by amateurs of young in crèche need confirmation; if true, interdiction of recreational banding mandated.

Conservation Status

No special status in any area of Western Hemisphere, apart from protection by various national statutes or international treaties and conventions.

Measures Adopted And Effectiveness

None beyond attempts, frequently successful, to coordinate regional dredge-spoil deposition programs and scheduling to maintain suitable colony sites at all times in favored locations in back bays, especially near inlets. Critical to success of these efforts has been deposition of spoil-slurry at apex of undiked islands where spoil allowed to assume natural angle of repose, grading off into shallow waters. This mimics natural processes and allows colonization by native coastal vegetation, plant succession to proceed at normal pace, and all but eliminates monoculture Phragmites “forests” inimical to Western Hemisphere colonial waterbirds.

Local protection of occupied sites by volunteer groups widespread in N. Carolina (Parnell et al. 1995). Posting of occupied sites 100 m from colony edges (per experimental results in Erwin 1989) successful in reducing human disturbance there (J. Parnell pers. comm.) and in Florida (R. T. Paul pers. comm.). All 3 techniques recommended for implementation (augmented by symbolic string fencing) at all colonies, with caveat that signs may act as attractive nuisances inducing people who might otherwise pass by without stopping to approach to read them. Dogs, even leashed, especially inimical to occupied Royal Tern colonies and should be especially guarded against.