D. Tommy King

Recent Population Status of the American White Pelican: A Continental Perspective

Abstract Breeding bird surveys were conducted at most American White Pelican (Pelecanus erythrorhynchos) colonies in North America from 1979-81 and the number of American White Pelicans was estimated at >109,000 breeding individuals in 55 colonies. Although many pelican colonies have not been surveyed since the early 1980s, we present the most current survey numbers available for North American colonies. Using available data (1998-2001) and the North American Continental Divide to delineate eastern from western metapopulations, 27 colonies and 48,240 nests in the East and 15 colonies and 18,790 nests in the West were documented, giving a total of about 134,000 breeding pelicans in North America. The nest numbers of 20 eastern and western colonies that were surveyed during 1979-81 and again in 1998-2001 were also compared to determine if pelican numbers are changing. The number of AWPE nests in those colonies has more than doubled since the 1979-81 surveys. Because current data for colonies in part of the United States and much of Canada are lacking and about 20 years have passed since more complete surveys were done, we propose that regular and coordinated North American pelican surveys should be initiated.

Effect of Roost Harassment on Cormorant Movements and Roosting in the Delta Region of Mississippi

Abstract Double-crested Cormorant (Phalacrocorax auritus) predation on Channel Catfish (Ictalurus punctatus) at commercial farms has been estimated to cost the Mississippi aquaculture industry approximately

Interactions Between the American White Pelican and Aquaculture in the Southeastern United States: an Overview

5 million annually to replace consumed fingerlings. In 1997, catfish producers assumed responsibility for the dispersal of cormorants in night roosts in the eastern (interior) delta region of Mississippi, where catfish farms are concentrated. We documented movements of 50 cormorants marked with radio transmitters in the delta region from January through March 1997. We obtained 161 post-capture day locations and 176 post-capture night roost locations. Cormorants that were harassed at their night roost flew farther to their next day’s location than birds that were not harassed the previous night. Of the cormorants for which we had more than one night roost location, only 11% of cormorants that were harassed returned to the same roost within 48 hours, compared with an 81% return of cormorants to a previously un-harassed night roost. Moreover, cormorants in the eastern portion of the delta (where all harassment was conducted) changed night roosts more frequently than cormorants in the western (non-harassed) delta. Since cormorants in our study foraged relatively close to their night roosts and only 11% of the birds that we observed roosting in the western delta traveled to the eastern delta to forage the following day, coordinated and intensive dispersal of cormorants from the interior delta may, temporarily, limit cormorant impacts to Mississippi aquaculture.

Double-crested Cormorant Movements in Relation to Aquaculture in Eastern Mississippi and Western Alabama

Abstract The eastern metapopulation of the American White Pelican (Pelecanus erythrorhynchos) breeds mainly in the Northern Great Plains, migrates through the Great Plains and along the Mississippi River and winters in the lower Mississippi River Valley and along the Gulf of Mexico. The production of farm-raised Channel Catfish (Ictalurus punctatus) in the southeastern United States has increased dramatically in the last 25 years. In 1990, U.S. Department of Agriculture Wildlife Services offices in Arkansas, Louisiana and Mississippi began receiving complaints concerning the foraging of pelicans in commercial Channel Catfish ponds. Because of the relatively shallow depth and high fish-stocking rates used by most catfish producers, these ponds provide an ideal foraging environment for the American White Pelican. Although the impact of foraging pelicans can be economically significant, the potential for pelicans to transmit trematode infections and other diseases to aquaculture facilities can be more destructive. Damage abatement recommendations have consisted of harassment measures similar to those used for other piscivorous birds, U.S. Fish and Wildlife Service Depredation Permits, and harassing the birds at their loafing sites.

Introduction: Biology and Conservation of the American White Pelican

Abstract Concomitant with increasing numbers of the Double-crested Cormorant (Phalacrocorax auritus), catfish producers in eastern Mississippi and western Alabama have reported damage caused by cormorant predation. VHF telemetry was used to document movements of 25 cormorants from all known night roosts in the aquaculture producing areas of eastern Mississippi and western Alabama, January-April 1998. A total of 193 day locations and 396 night roost locations of the cormorants were obtained. Each cormorant was found in the study area for 57 ± 4 (SE) days. Each cormorant averaged three night roosts (range: 1-8) and spent 20 (±2) days at each night roost site. Over 95% of cormorant day locations were within 19 km of their night roosts. Catfish pond use by cormorants varied between roost sites. Cormorants from five of eleven night roosts had ≥30% of subsequent daytime locations on catfish ponds and birds from five of the six remaining night roosts did not visit catfish ponds on the following day. Foraging distance and frequency of night roost interchange was less for birds in this study than those reported from other aquaculture regions. We suggest roost harassment efforts should be focused on specific roost sites and some roost sites should serve as unharrassed refugia from which cormorants are less likely to cause damage to aquaculture.

Distribution, Abundance and Habitat Use of American White Pelicans in the Delta Region of Mississippi and Along the Western Gulf of Mexico Coast

Abstract Two separate, large-scale management units for the American White Pelican (Pelecanus erythrorhynchos) in North America are proposed: the eastern and western metapopulations, separated by the North American Continental Divide. The populations on either side of this barrier are subject to contrasting ecological conditions, movement patterns suggest strong geographic separation and each is likely demographically distinct. Subdivisions within these demographic units need to be more precisely defined in the future. Yet, because of the highly colonial nesting habits of the American White Pelican, conservation can still be effective if directed toward separate breeding colonies. Our intent is to provide a compilation of current knowledge regarding species status, distribution and ecology. Herein, further study is recommended: (1) to determine genetic characteristics and the degree of genetic separation of the various geographic divisions in the range of the species to help ultimately better define “evolutionarily significant units” for American White Pelican conservation, (2) to study movements and genetic exchange among and between these divisions, and (3) to study movement patterns and genetic mixing among these divisions during long- and short-term changes in environmental conditions.

The Use of Culmen Length to Determine Sex of the American White Pelican

Abstract Aerial surveys of American White Pelicans (Pelecanus erythrorhynchos) were conducted over coastal Louisiana and the delta region of Mississippi on 1-2 days during December, February, and April each year from 1997 to 1999. Additional surveys were conducted in coastal Texas and Mexico during January 1998 and 1999. The numbers, location, and habitat of all pelicans observed were recorded. The coastal zone of Louisiana consistently had higher numbers of pelicans (18,000 to 35,000 birds) than other areas surveyed (3,000 to 8,000 birds), indicating that Louisiana may be the most important wintering area for American White Pelicans east of the Rocky Mountains. Among the four regions surveyed, the average size of pelican flocks was largest in Mississippi during January-February, particularly in 1999 (x̄ = 245 birds/flock). Pelican numbers in Mississippi peaked in February but in Louisiana they were more variable. Pelicans in the delta region of Mississippi were found most often in fresh water and sand bar habitats during December, flooded field habitats during February, and catfish ponds in April. In Louisiana, pelicans used fresh, intermediate, and brackish marshes during December, but showed a preference for brackish and saline marshes in February and April.

16 Bird depredation

Abstract Culmen length has been suggested as being diagnostic for sex in the American White Pelicans (Pelecanus erythrorhynchos). However, the literature on the use of culmen length to determine sex is inconsistent, with reported overlap in culmen lengths for males and females ranging from 1 mm to >120 mm. Morphological measurements from 188 American White Pelicans collected in Mississippi and Louisiana whose sex was determined by dissection and gonadal inspection were measured. The use of culmen length alone was used to determine gender for this sample by establishing the minimum observed culmen length for males and the maximum observed culmen length for females that provided the fewest incorrect determinations for each gender. A multivariate discriminant function model was developed to determine sex from our data and compared the diagnostic accuracy of the model with the accuracy based on culmen length alone. Both methods were validated using an independently collected sample of 22 pelicans from Florida. A culmen length of ≥310 mm for males and ≤309 mm for females from our data correctly classified sex for 99% of American White Pelicans from our Mississippi and Louisiana samples and 95% of AWPE for the Florida sample. Culmen length and wingcord length were significant variables in the discriminant function model. The resulting model correctly classified sex of 97% of the birds and 94% of the independent Florida sample. The culmen length alone predicted the sex of American White Pelicans as well as multivariate methods and provides an accurate simple, non-lethal method for sexing the species.

Summer and Migrational Movements of Satellite-Marked Double-Crested Cormorants from a Breeding Colony Managed by Egg-Oiling in Lake Ontario, USA

Publisher Summary A variety of avian and mammalian predators is attracted to aquaculture facilities in the United States because ponds and open raceways provide a constant and readily accessible food supply for these animals. However, the mere presence of these predators around aquaculture facilities does not necessarily mean that significant depredation problems are occurring. At catfish farms, three species or species groups of birds are primarily cited by catfish producers as causing most depredation problems. These include double-crested cormorants, wading birds (herons and egrets), and American white pelicans, in order of importance to catfish producers. Although all of these species consume catfish, their biology, distribution, and dietary preferences dictate the extent of depredation problems they cause and the approaches needed to alleviate their depredations. With the exception of total bird exclusion from ponds, there are no simple solutions for resolving all bird depredation problems in catfish aquaculture. Thus, in most cases, an integrated management approach to alleviating bird depredations must be considered.

Home Ranges and Habitat Use of Brown Pelicans (Pelecanus occidentalis) in the Northern Gulf of Mexico

Abstract. n A two-year satellite telemetry study was initiated in May 2000 at a Double-crested Cormorant (Phalacrocorax auritus) breeding colony on Little Galloo Island (LGI) in eastern Lake Ontario, New York, USA, which is managed by egg-oiling. The objective was to describe cormorant (N = 26/year) movements, specifically during the period of reproductive management by egg-oiling and seasonally (breeding, migration and wintering). Egg-oiling at two-week intervals resulted in a hatch success on LGI of 5.7% for 2000 and 2001, combined. The majority (97%) of core use areas of marked cormorants contained LGI throughout three egg-oiling treatments (six weeks), and 71% still contained LGI by the end of the final (fourth) treatment (eight weeks). Of cormorants that moved during or after control activities, three remained in the vicinity of active breeding colonies for over three months. Cormorants initiated fall migration over a 16-week period ranging from 12 July to 29 October, with a mean departure date of 6 September (N = 24, SE = 8 days) over both years. Mean duration of fall migration was 34 days (N = 19, SE = 7 days, range = 108 days). Most (75%) cormorants captured at LGI migrated east of the Appalachian Mountains, and their winter range extended from southeastern Louisiana, along the coast of the Gulf of Mexico, to the southern portion of the Atlantic coast. Although three (13%) cormorants over both years relocated to other active colonies for long enough periods (over three months) to potentially raise young, this study indicates that control efforts did not result in complete abandonment of LGI. Egg-oiling was successful in reducing recruitment within breeding seasons, and within-breeding-season renesting attempts by cormorants in this study were limited and likely unsuccessful. Further evaluation and refinement of egg-oiling as a management tool will require multiyear monitoring of the LGI cormorant breeding colony.