Breeding colonial waterbirds are particularly susceptible to human disturbance because of their high-density nesting habtt~ Identified detriments to reproductive success include egg and nestling mortality, nest evao~tior~ reduced nestling body mass and slower growth, premature fledging and modified adult behaviorg Fifteen species of colonial waterbtrds nesttng at 17 colonies in north and central Florida were exposed to three different human disturbance mechanisms (HDMs) in order to determine recommended set-back (RS) distances for protecting these mixed-species nesting assemblage~ Both intraspeciflc and inter. specific variation were observed in flushing response distances to the same human disturbance mechani.¢mg In genera~ colonial waterbirds exhibited greater average flush distances in reaction to a walking approach than to approaching motor boat~ Recommended set-back distances were estimated using a formula based on the mean plus 1.6495 standard deviations of the observed flushing distances plus 40 meters ~S = exp (# + 1.64950 + 40)]. In genera~ a recommended set-back distance of about 100 meters for wading bird colonies and 180 meters for mixed tern~skimmer colonies should be adequate to effectively buffer the sites we studied from human disturbance caused by approach of pedestrians and motor boats. We recommend follow-up studies to test our model at other breeding colonies.Distancia de alejamiento para proteger de las perturbaciones humanas alas colonias de aves nidificadoras en Florida Resumen: Las ayes acu~ticas que habitan en colonias durante el pertodo de criag son particularmente susceptibles alas perturbaciones humanas por sus hdbitos conducentes a una alta demidad de nido~ Los factore$ que disrainuyen el dxito reproductivo, tncluyen ia mortaltdad del huevo y el ptch6r 6 la evacuaci6n del nid~ la reducci6n de la masa corporal del pich6n o crecimeiento lento, el abandono prematuro del ntdo por parte de los pie.hones y comportamtentos adultos modificados Quince especies de colonias de ave$ acu~ticas que nidtflcaron en 17 colontas del norte y centro de Floridg fueron expuestas a 3 mecanismos de perturbaci6n humana dtferenteg a los efectos de deterrainar distanctas de alejamtento recomendables para proteger las agregaciones mtxtas de dstas especie£ Variactones tntra-especificas e inter-especificas en ias distanctas de respuesta frente a los mismos mecanismos de perturbaci6n humana En genera~ los colonias de ayes acu~ttcas exhtbteron una mayor dtstancia promedio antes de volar en reacct6n a la cercania de pasos que al acercamiento de una embareactbn a motor. La dgstancia recomendada de alejamiento rue esttmada utilizando una f6rmul~ basada en la media md~ 1.6495 desvtaciones standard de la distancias antes de volar observad~ md$ 40 m ~RS = exp (# + 1. 64958 + 40)]. En genera~ una distancia de alejamiento de alrededor de 100 m para lus colontas de aves zancudas y 180 m para las colonias mtxtas ("tern/skimmer"), seria adecuada para amortiguar a los sitios que estudiamos de los tmpactos de las perturbaciones ...

We describe improvements to monitoring/indexing methodology for predators of marine turtle nests on the east coast of Florida, and the resulting marine turtle conservation implications from integrating the methodology into predator management. A strip transect from dune line to the shore improved an already successful design for monitoring raccoons, and was also sensitive for armadillos. The data were integrated into predator management operations to effectively and efficiently remove the species responsible for turtle nest predation. Tracking plot data also served to validate predator patterns of behavior relative to turtle nesting and improve prospects for preventive predator management strategies. Perhaps the most important finding is that predation at a beach historically suffering nearly complete losses (95%) of marine turtle nests had nest predation reduced to nominal levels (9.4%). For 2002 this predation level represents an estimated 69,000 additional hatchling turtles produced over historical predation rates, and 16,700 additional hatchlings over the previous lowest predation rate.

Hobe Sound National Wildlife Refuge (HSNWR) on Florida's east coast provides undisturbed nesting habitat for three species of threatened or endangered marine turtles. Predation by raccoons and armadillos poses the greatest risk to turtle nests, and predator control has been identified as the most important management tool for enhancing nesting productivity. Recently, estimates of the number of nests that would have been lost in the 2000 nesting and incubation season were made using the results from four control approaches. These approaches were, in order of descending complexity: (1) refuge control enhanced by a one person-month contract with federal control specialists, with that control optimized using a passive tracking methodology for monitoring predators; (2) refuge control enhanced by a one person-month contract with federal control specialists, without predator monitoring; (3) refuge control, but no contract with specialists; (4) no control. In that analysis, approach 1 resulted in the fewest turtles lost to predation. In this paper, we perform a benefit Á/cost analysis to determine if operational efficacy translates into economic efficiency. Approach 1 had by far the best benefit Á/cost ratio for loggerhead turtles, but approach 2 was best for Atlantic green and leatherback turtles. However, almost 90% of the turtles nesting at HSNWR are loggerhead, and this area is vital to loggerhead survival. Thus, approach 1 also had by far the best benefit Á/cost ratio over all turtle species, saving approximately $1.7 million over approach 2, $2.6 million over approach 3 and $8.4 million over approach 4. Given these results, one must ask how can we afford not to control predators, and furthermore, how can we not afford to take the minimal extra steps to maximize control efficacy.

Feral swine (Sus scrofa) adversely affect the environment in many of the places where they have been introduced. Such is the case in Florida, but quantification and economic evaluation of the damage can provide objective bases for developing strategies to protect habitats. Swine damage to native wet pine-flatwoods at three state parks in Florida was monitored from winter 2002 to winter 2003. Economic valuations of damage were based on the US dollar amounts that wetland regulators have allowed permit applicants to spend in attempts to replace lost resources. The parks had different swine management histories and the damage patterns differed among them over time. Swine were intensively removed in 2000 from the first park, and it initially had the lowest habitat damage at 1.3%, but as a result of natural and artificial population growth this damage rose to 5.4% by the conclusion of the study, and was valued at US$ 19 193–36 498 ha−1. The second park had no history of swine harvest and, over the monitoring period, damage escalated from 2.6%–6.4%, with an associated value of US$ 22 747–43 257 ha−1. Swine were managed as game animals in the third park prior to its inclusion into the state parks system in 2000. Within this park, the proportion of area damaged decreased from 4.3%–1.5%, valued at US$ 5 331–10 138 ha−1. This decrease may be a result of human activities associated with development of the park's infrastructure causing dispersal of animals conditioned to avoid humans by hunting. Damage was highly scattered in each park, as evidenced by a much higher proportion of sampling sites showing damage than the actual proportion of land area damaged. The dispersed nature of small amounts of damage would increase the effort required to recover habitat and thus damage value estimates are probably conservative. It was also impossible to incorporate values for such contingencies as swine impact to state and federally listed endangered plants in the parks, some of which are found nowhere else in the world.

The beach at Hobe Sound National Wildlife Refuge (HSNWR) is a high-density nesting beach serving three species of threatened and endangered sea turtles. Historically, up to 95% of turtle nests at HSNWR were lost to predation by raccoons and armadillos. Consequently, predator control was identified as the most important conservation tool at HSNWR, and predator control optimised by predator monitoring led to highly successful results whereby predation had been reduced to low levels (7–13.5% of monitored nests) in 2002 and 2003. In 2004, funding shortfalls caused predator control to be curtailed with ~1.5–2 months remaining in the nesting/hatching season. We analysed the resulting effects on turtle nest predation levels compared with the results from 2002 and 2003. The predation rate in 2004 compared favourably with that of 2002 and 2003 until the end of June, after which control was curtailed. Thereafter, predation rapidly accelerated, with the 2004 predation rate increasing to 1.5–3 times the rates from 2002 and 2003 by the end of August. The discrepancy in all likelihood would have grown further, except Hurricane Frances destroyed all remaining nests with 1.5–2 months left in the nesting/hatching season. Product-limit survival analyses demonstrated substantial differences in turtle nest survival between 2004 versus 2002 and 2003, but not between 2002 and 2003. When analysed as cohorts based on month of nest deposition, no differences were found among 2002, 2003, 2004 for nests deposited in May. These nests received full protection from predation in each of the three years. However, the survival analyses for nests deposited in June, and those deposited in July showed inferior survival for 2004 when predator control was removed for the last half of nesting/hatching.