ACCESS NUMBER: 00014

STUDY TITLE: Eastern Brown Pelicans: Dispersal, Seasonal Movements, and Monitoring of PAHs and 

Other Oil Contaminants Among Breeding Colonies in the Northern Gulf of Mexico

REPORT TITLE: Ecological drivers of brown pelican movement patterns, health, and reproductive 

success in the Gulf of Mexico

CONTRACT NUMBER: M12PG00014

SPONSORING OCS REGION: Gulf of Mexico

APPLICABLE PLANNING AREA(S): Western Gulf, Central Gulf, Eastern Gulf

FISCAL YEAR(S) OF PROJECT FUNDING: 2012–2019

COMPLETION DATE OF REPORT: May 2019

COSTS: $1.2M

PROJECT MANAGER(S): Dr. Patrick Jodice

AFFILIATION of Project manager: US Geological Survey South Carolina Cooperative Fish and Wildlife 

Research Unit

ADDRESS: 260 Lehotsky Hall, Clemson University, Clemson, SC, 29634

PRINCIPAL INVESTIGATOR(S)1: Dr. Patrick Jodice

KEY WORDS: brown pelican, diet, migration, nutritional stress, polycyclic aromatic hydrocarbons, risk 

exposure, spatial ecology, tracking

BRIEF ABSTRACT: We investigated spatial, reproductive, and physiological ecology of brown pelicans

(Pelecanus occidentalis) throughout the northern Gulf of Mexico (GOM). Home range size and the 

probability and distance of migration were positively correlated with colony size. Pelicans from all colonies 

overlapped in space use in the Mississippi River Delta region of Louisiana during the nonbreeding 

season. Diet was primarily menhaden in the eastern and central regions but was more varied in the 

western region. Risk of exposure to contaminants was often higher in the west and central GOM

compared to the eastern GOM, although factors other than region also contributed to exposure risk. 

BACKGROUND: The GOM contains a high density of oil infrastructure and also supports a rich 

assemblage of seabirds. Understanding the effects of oil and gas activity on seabirds in the region 

requires a thorough understanding of reproductive ecology, foraging ecology, physiology, and habitat use. 

Because of its distribution patterns, behavior, and known sensitivity to contaminants, the brown pelican is 

a good indicator of species-level effects of interaction with coastal and marine development. 

OBJECTIVES: Our objectives were to assess reproductive ecology, movement patterns, habitat use, diet, 

physiology, and exposure to polycyclic aromatic hydrocarbons.

DESCRIPTION: Research was conducted at seven pelican colonies throughout the Northern GOM 

between 83° and 98° W and 27° and 31° N. We deployed 85 GPS satellite tags on breeding adults to 

measure and describe home ranges, migration strategies, and risk exposure to oil and gas development 

and other surface pollutants. We also collected data on colonies (e.g., reproductive success, diet,

contaminants).

SIGNIFICANT CONCLUSIONS: Most of the response variables we measured or modeled varied 

substantially among colonies and regions, although individual characteristics also were significant. The 

effects of environmental or anthropogenic stressors on pelicans may differ based on a combination of 

environmental, individual, and colony-based attributes and may not be strictly “region-based”. The use of 

the Mississippi River Delta region of Louisiana during migration by individuals from all regions suggests 

this is a hot spot for pelicans and risk exposure. 

1

P.I.’s affiliation may be different than that listed for Project Manager(s).
ACCESS NUMBER: 00014

STUDY RESULTS: Colony size was positively related to home range size, and to distance and probability 

of migration. Individuals from different colonies and regions overlapped spatially and temporally during 

breeding, staging, and migration. These overlap areas (e.g., the Mississippi River Delta region of 

Louisiana) represent hot spots for pelicans at specific times of year, such as staging and migration. 

Menhaden made up 60–85% of the diet of pelican chicks at colonies within the summer range of 

menhaden, but < 40% at colonies outside of the core summer range of menhaden (i.e., Texas).

Reproductive success was positively related to meal provisioning rates, which, in turn, were lowest at 

colonies in Texas. Fledging success was positively related to stress levels and body condition of chicks. 

Exposure to oil and gas activity, surface pollutants, and shipping lanes was least in the east region; it was

higher but similar between the central and west regions. The similarity in exposure between the central 

and west regions is due to inclusion of multiple sources of risk. Hot spots of risk were located in the 

Mississippi River Delta (Louisiana) and Galveston Bay (Texas). The PAH profile of brown pelicans in the 

northern Gulf of Mexico was diverse and made up predominantly of alkylated PAHs. The level of oil and 

gas development in a region was not consistently the best predictor of PAH levels or individual health, 

and other factors (e.g., body condition, sex) also were influential. 

STUDY PRODUCT(S): Primary products are noted; a complete list is available in the report.

Lamb JS, Satgé YG, Streker RA, Jodice PGR. 2020. Ecological drivers of brown pelican movement 

patterns, health, and reproductive success in the Gulf of Mexico. New Orleans (LA): US Department 

of the Interior, Bureau of Ocean Energy Management. 234 p. Report No.: BOEM 2020-036. Contract 

No.: M12PG00014. 

Lamb JS. 2016. Ecological drivers of brown pelican movement patterns and reproductive success in the 

Gulf of Mexico [dissertation]. Clemson (SC): Clemson University.

Lamb JS, O’Reilly KM, Jodice PGR. Jodice. 2016. Physical condition and stress levels during early 

development reflect feeding rates and predict pre- and post-fledging survival in a nearshore 

seabird. Conserv Physiol. 4(1): cow060. 

Lamb JS, Satgé YG, Fiorello CV, Jodice PGR. 2016. Behavioral and reproductive effects of bird-borne 

data logger attachment on Brown Pelicans (Pelecanus occidentalis) on three temporal scales. J 

Ornith. 158: 617-627. 

Lamb JS, Satgé YG, Jodice PGR. 2017. Diet composition and provisioning rates of nestlings determine 

reproductive success in a subtropical seabird. Mar Ecol Prog Ser. 581:149-164. 

Lamb JS, Satgé YG, Jodice PGR. 2017. Influence of density-dependent competition on foraging and 

migratory behavior of a subtropical colonial seabird. Ecol Evol 2017;00:1–13.

Streker R. 2019. Reproductive ecology and diet of brown pelicans in the Gulf of Mexico [thesis].

Clemson (SC): Clemson University.

Lamb JS, Satgé YG, Jodice PGR. 2020. Environmental and behavioral drivers of annual-cycle habitat 

selection in a nearshore seabird, the Brown Pelican. Divers Distrib. 26(2): 254–266.