Evaluation of Moderate and Low-Powered Lasers for Dispersing Double-Crested Cormorants from Their Night Roosts

The double-crested cormorant (Phalacrocorax auritus) is the primary avian predator on the southern catfish industry, estimated to cause $5 million in damage per year. To date, the most effective strategy for alleviating cormorant depredations in areas of intensive catfish production is coordinated dispersal of cormorant night roosts with pyrotechnics. Many of these night roosts are located in waterfowl refuges or wetland habitat leased for waterfowl hunting. Thus, there is an increasing concern about the effects of cormorant harassment efforts on waterfowl and other wildlife inhabiting these sites in cypress-swamp habitat. To address the need for a roost harassment device that was more species-specific, we evaluated two commercially available low- to moderate-powered lasers in a series of large-pen and field trials for their effectiveness in moving cormorants from test ponds and dispersing cormorants from their night roosts, respectively. In pen trials, laser beams directed at small groups of captive birds produced negligible effects, suggesting that the laser light was not highly aversive. This was consistent with a series of veterinary investigations suggesting no detectable ocular damage to cormorant eyes directly exposed to a selected laser at varying distances down to 1 m. During field trials both lasers, directed at roost trees after sunset, were consistently effective in dispersing cormorants in 1 to 3 evenings of harassment and is comparable to the harassment effort needed with pyrotechnics. Because laser treatment is completely silent and can be directed selectively at cormorants, these devices may be extremely useful for dispersing cormorants in sites where disturbance of other wildlife is a concern. Advantages and disadvantages of lasers relative to pyrotechnics are discussed

Potential of Double-crested Cormorants (\u3ci\u3ePhalacrocorax auritus\u3c/i\u3e), American White Pelicans (\u3ci\u3ePelecanus erythrorhynchos\u3c/i\u3e), and Wood Storks (\u3ci\u3eMycteria americana\u3c/i\u3e) to Transmit a Hypervirulent Strain of \u3ci\u3eAeromonas hydrophila\u3c/i\u3e between Channel Catfish Culture Ponds

Aeromonas hydrophila is a Gramnegative bacterium ubiquitous to freshwater and brackish aquatic environments that can cause disease in fish, humans, reptiles, and birds. Recent severe outbreaks of disease in commercial channel catfish (Ictalurus punctatus) aquaculture ponds have been associated with a hypervirulent Aeromonas hydrophila strain (VAH) that is genetically distinct from less virulent strains. The epidemiology of this disease has not been determined. Given that research has shown that Great Egrets (Ardea alba) can shed viable hypervirulent A. hydrophila after consuming diseased fish, we hypothesized that Doublecrested Cormorants (Phalacrocorax auritus), American White Pelicans (Pelecanus erythrorhynchos), and Wood Storks (Mycteria americana) could also serve as a reservoir for VAH and spread the pathogen during predation of fish in uninfected catfish ponds. All three species, when fed VAH-infected catfish, shed viable VAH in their feces, demonstrating their potential to spread VAH

Great Egret Preference for Catfish Size Classes

Several species of fish-eating birds are commonly observed near aquaculture facilities in the southern United States. An understanding of the relationships between these birds and specific commodities is needed to interpret and manage bird impacts to aquacultural production. We conducted two foraging experiments to evaluate the preference o f Great Egrets (Ardea alba) for three specific size classes of Channel Catfish (Zctalurus punctatus). During six no-choice feeding trials, egrets consumed significantly more small (7.5-10 cm) fingerlings than medium (13- 18 cm) or large (23-23 cm) catfish. Egrets captured 19 large catfish, and ingested only two, even when no other fish were available. During two-choice trials, Great Egrets significantly preferred small fingerlings to medium-sized fish, and medium-sized catfish to large fish. Handling time was directly related to the size of catfish ingested. Handling time was inversely related to the number of catfish ingested from each size class, particularly when Great Egrets were given a choice between two catfish size classes. Thus, we infer that the ease of capture and physical defenses (e.g., catfish spines) associated with particular foods affect Great Egret foraging preferences. Management of Great Egret impacts to aquacultural production should focus on dispersing egrets from ponds containing small (\u3c18 cm) Channel Catfish, rather than generalized dispersal at all ponds on all farms. Received 1 October 2000, accepted 18 April 2001

Evaluation of moderate and low-powered lasers for dispersing double-crested cormorants from their night roosts

The double-crested cormorant (Phalacrocorax auritus) is the primary avian predator on the southern catfish industry, estimated to cause $5 million in damage per year. To date, the most effective strategy for alleviating cormorant depredations in areas of intensive catfish production is coordinated dispersal of cormorant night roosts with pyrotechnics. Many of these night roosts are located in waterfowl refuges or wetland habitat leased for waterfowl hunting. Thus, there is an increasing concern about the effects of cormorant harassment efforts on waterfowl and other wildlife inhabiting these sites in cypress-swamp habitat. To address the need for a roost harassment device that was more species-specific, we evaluated two commercially available low- to moderate-powered lasers in a series of large-pen and field trials for their effectiveness in moving cormorants from test ponds and dispersing cormorants from their night roosts, respectively. In pen trials, laser beams directed at small groups of captive birds produced negligible effects, suggesting that the laser light was not highly aversive. This was consistent with a series of veterinary investigations suggesting no detectable ocular damage to cormorant eyes directly exposed to a selected laser at varying distances down to 1 m. During field trials both lasers, directed at roost trees after sunset, were consistently effective in dispersing cormorants in 1 to 3 evenings of harassment and is comparable to the harassment effort needed with pyrotechnics. Because laser treatment is completely silent and can be directed selectively at cormorants, these devices may be extremely useful for dispersing cormorants in sites where disturbance of other wildlife is a concern. Advantages and disadvantages of lasers relative to pyrotechnics are discussed

Potential of Double-crested Cormorants (\u3ci\u3ePhalacrocorax auritus\u3c/i\u3e), American White Pelicans (\u3ci\u3ePelecanus erythrorhynchos\u3c/i\u3e), and Wood Storks (\u3ci\u3eMycteria americana\u3c/i\u3e) to Transmit a Hypervirulent Strain of \u3ci\u3eAeromonas hydrophila\u3c/i\u3e between Channel Catfish Culture Ponds

Aeromonas hydrophila is a Gramnegative bacterium ubiquitous to freshwater and brackish aquatic environments that can cause disease in fish, humans, reptiles, and birds. Recent severe outbreaks of disease in commercial channel catfish (Ictalurus punctatus) aquaculture ponds have been associated with a hypervirulent Aeromonas hydrophila strain (VAH) that is genetically distinct from less virulent strains. The epidemiology of this disease has not been determined. Given that research has shown that Great Egrets (Ardea alba) can shed viable hypervirulent A. hydrophila after consuming diseased fish, we hypothesized that Doublecrested Cormorants (Phalacrocorax auritus), American White Pelicans (Pelecanus erythrorhynchos), and Wood Storks (Mycteria americana) could also serve as a reservoir for VAH and spread the pathogen during predation of fish in uninfected catfish ponds. All three species, when fed VAH-infected catfish, shed viable VAH in their feces, demonstrating their potential to spread VAH

Green and Blue Lasers are Ineffectivefor Dispersing Deer at Night

Over-abundant populations of white-tailed deer (Odocoileus virginianus) create agriculturaland human health and safety issues. The increased economic damage associated with locally overabundant deer populations accentuates the need for efficient techniques to mitigate the losses. Although red lasers can be an efficient tool for reducing damage caused by birds, they are not effective for deer because deer cannot detect wavelengths in the red portion of the spectrum. No research has been conducted to determine if lasers of lower wavelengths could function as frightening devices for deer. We evaluated agreen laser (534nm, 120mW)and 2 models of blue lasers (473nm, 5 mW and 15 mW) to determine their efficacy in dispersing deer at night. Deer were no more likely to flee during a green or blue laser encounter than during control encounters. The green and blue lasers we tested did not frighten deer

Red lasers are ineffective for dispersing deer at night

Populations of white-tailed deer (Odocoileus virginianus) and the number of deer-human conflicts have increased in recent years, emphasizing the need for efficient and inexpensive methods to reduce site-specific deer damage. Recent research using laser technology to disperse a variety of bird species has yielded promising results, prompting wildlife professionals and the public to question whether lasers could play a role in reducing damage and conflict with mammals, primarily deer. We evaluated 2 red lasers (63-650 nm) to determine their effectiveness as devices to frighten deer. No differences occurred in flight response between lasers or between the control and lasers. We suggest that deer were not frightened by either model of laser because they could not detect red laser beams or their intense brightness. Red lasers do not appear to have potential as frightening devices for deer

POTENTIAL FOR GREAT EGRETS (\u3ci\u3eARDEA ALBA\u3c/i\u3e) TO TRANSMIT A VIRULENT STRAIN OF \u3ci\u3eAEROMONAS HYDROPHILA\u3c/i\u3e AMONG CHANNEL CATFISH (\u3ci\u3eICTALURUS PUNCTATUS\u3c/i\u3e) CULTURE PONDS

Aeromonas hydrophila is a gram-negative, rod-shaped, facultative, anaerobic bacterium that is ubiquitous in freshwater and slightly brackish aquatic environments and infects fish, humans, reptiles, and birds. Recent severe outbreaks of disease in commercial channel catfish (Ictalurus punctatus) aquaculture ponds have been associated with a highly virulent A. hydrophila strain (VAH), which is genetically distinct from less-virulent strains. The epidemiology of this disease has not been determined. Given that A. hydrophila infects birds, we hypothesized that fish-eating birds may serve as a reservoir for VAH and spread the pathogen by flying to uninfected ponds. Great Egrets (Ardea alba) were used in this transmission model because these wading birds frequently prey on farmed catfish. Great Egrets that were fed VAH-infected catfish shed VAH in feces demonstrating their potential to spread VAH

Dynamics of virus shedding and antibody responses in influenza A virus-infected feral swine

Given their free-ranging habits, feral swine could serve as reservoirs or spatially dynamic ‘mixing vessels’ for influenza A virus (IAV). To better understand virus shedding patterns and antibody response dynamics in the context of IAV surveillance amongst feral swine, we used IAV of feral swine origin to perform infection experiments. The virus was highly infectious and transmissible in feral swine, and virus shedding patterns and antibody response dynamics were similar to those in domestic swine. In the virus-inoculated and sentinel groups, virus shedding lasteddays, respectively. Antibody titres in inoculated swine peaked at 1 : 840 on day 11 post-inoculation (p.i.), remained there until 21 days p.i. and dropped to: 220 at 42 days p.i. Genomic sequencing identified changes in wildtype (WT) viruses and isolates from sentinel swine, most notably an amino acid divergence in nucleoprotein position 473. Using data from cell culture as a benchmark, sensitivity and specificity of a matrix gene-based quantitative reverse transcription-PCR method using nasal swab samples for detection of IAV in feral swine were 78.9 and 78.1 %, respectively. Using data from haemagglutination inhibition assays as a benchmark, sensitivity and specificity of an ELISA for detection of IAV-specific antibody were 95.4 and 95.0 %, respectively. Serological surveillance from 2009 to 2014 showed that ~7.58 % of feral swine in the USA were positive for IAV. Our findings confirm the susceptibility of IAV infection and the high transmission ability of IAV amongst feral swine, and also suggest the need for continued surveillance of IAVs in feral swine populations