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History and Nesting Population of Bald Eagles in Louisiana
Nickolas R. Smith, Thomas J. Hess Jr., and Alan D. Afton

Southeastern Naturalist, Volume 15, Issue 1 (2016): 12–25

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Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 12 2016 SOUTHEASTERN NATURALIST 15(1):12–25 History and Nesting Population of Bald Eagles in Louisiana Nickolas R. Smith1,2,*, Thomas J. Hess Jr.3, and Alan D. Afton4 Abstract - The population of nesting Haliaeetus leucocephalus (Bald Eagle) in Louisiana reached precariously low numbers in the early 1970s after experiencing marked declines similar to the rest of the continental population. From 1975 to 2008, aerial surveys of all known nests have been conducted within the state to monitor the population. We used data collected over the 34-year nest-monitoring program to quantify the recovery of the nesting population in Louisiana. Active nests increased exponentially from 7 to 387, exhibiting a mean annual rate of increase of 11.1 ± 0.3% per year with no indications of slowing. Accounting for increases in nests over the monitoring period, we found relatively slight changes in reproduction, with productivity and brood size peaking in 2000 and 1999. By 1990, the nesting population in Louisiana had exceeded each goal of the Southeastern States Bald Eagle Recovery Plan, and the species was removed from the federal list of endangered and threatened wildlife in 2007. However, the continued stability and growth of the nesting population may depend on the ability of Bald Eagles to cope with increasing levels of human activity, as well as the protection and availability of current and future nesting habitats. Introduction Haliaeetus leucocephalus L. (Bald Eagle) experienced a marked population decline throughout the continental United States in the mid-1900s, reaching an estimated low of 417 pairs in 1963 (Sprunt and Ligas 1964). The continental population began to increase after the ban on DDT in 1972 and through federal listing of the Bald Eagle as an endangered and threatened species in 1978 (Buehler 2000, USFWS 1978). By 2007, the species was removed from the federal list of endangered and threatened wildlife (USFWS 2007); however, it continues to be protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act, and remains a species of conservation concern in Louisiana (Lester et al. 2005). In the early 1900s, Bald Eagles were described as being common in Louisiana (Bailey 1919) and documented to be nesting in various parts of the state but mainly near the coast (Beyer 1900, Beyer et al. 1908). The population subsequently declined, with reports of only “six or seven active nests” in 1972 (Ray Aycock in Lowery 1974). Similar to the continental population, the decline in Louisiana was believed to be linked to DDT, habitat destruction, and human persecution (Murphy 1989, USFWS 2007). 1School of Renewable Natural Resources, Louisiana State University, Baton Rouge, LA 70803. 2Current Address - Ducks Unlimited Inc., One Waterfowl Way, Memphis TN 38120. 3Louisiana Department of Wildlife and Fisheries, Rockefeller Refuge, 5476 Grand Chenier Hwy, Grand Chenier, LA 70743 (deceased). 4US Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, Louisiana State University, Baton Rouge, LA 70803. *Corresponding author - Manuscript Editor: Frank Moore Southeastern Naturalist 13 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 The continental decline prompted the listing of the Bald Eagle as an endangered species throughout its southern range, and subsequent efforts were focused at increasing the breeding population (USFWS 1978). In 1984, a collective recovery plan (Murphy 1989) was compiled for the southeastern region, which included Louisiana. The goals of the recovery plan were to achieve a collective 3-year average of >0.9 young per active nest, >1.5 young per successful nest, and >50% of nests successful in raising at least 1 young, as well as to establish a monitoring protocol to measure population vigor and determine if adequate habitat exists. Aerial nest-monitoring has been used in Louisiana since 1975 to document population change of Bald Eagles and evaluate management effectiveness (Payne 1975). Our objectives were to document the recovery of Louisiana’s nesting population of Bald Eagles, using data collected during the nest-monitoring program, which was employed from 1975 to 2008. Finally, we assessed the population increase in Louisiana with regard to the overall recovery of the Bald Eagle in the southeastern region. Methods Aerial survey data were collected annually for known Bald Eagle nests in Louisiana from 1975 to 2008. In Louisiana, nesting occurs in the winter, with egg laying typically occurring from late September to early February (Louisiana Department of Wildlife and Fisheries 2005). Herein we designate year by reference to the springtime portion of the nesting season (e.g., 1974–1975 winter nesting season = 1975). Reports of nesting activity and nests were provided by private individuals, state and federal personnel, and the media. Additionally, other nests were found during nest-monitoring activities and incorporated into subsequent surveys. From 1975 to 1985, nest surveys were conducted by the US Fish and Wildlife Service (USFWS); surveys were continued from 1985–2008 by the Louisiana Department of Wildlife and Fisheries (LDWF) using the same protocol. Attempts were made to survey known nests at least twice annually, using a Bell Jet Ranger Model 206B helicopter or a fixed-wing aircraft, such as a Cessna 210 or Cessna 185 float plane. Aerial-survey techniques used were similar to methodologies reported by Grier et al. (1981) for fixed-wing aircraft and Watson (1993) for helicopters. Coordinates (latitude and longitude) of nests sites were recorded using Loran C navigation equipment until 1992, after which global positioning system (GPS) equipment was used. Using the standard 2-flight method (Fraser et al. 1983), the first survey flight was conducted annually during the egg-laying and incubation periods (October– January) to determine activity of known nests and locate new nests. Nests were classified as active by the presence of at least one of the following: (1) one or more adults in or near a nest with signs of nest refurbishment (i.e., presence of fresh nesting material); (2) an adult sitting low in the nest presumably incubating; or (3) the presence of eggs or young. Within the same nesting season, active nests were revisited during a second flight survey, conducted during January–May, Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 14 to assess annual nest success, productivity, and mean brood size (henceforth, collectively referred to as production). Nests were recorded as successful if a minimum of 1 young, 8 weeks of age or greater, was observed. Annual nesting success was defined as the proportion of successful nests per active nests with known outcomes. Productivity was the mean number of young produced per active nests with known outcomes. Mean brood size was the mean number of young produced per successful nest. From 2004 to 2008, complete sampling of all nests for production was logistically impractical because the nesting population had expanded over a large geographic area. Therefore during this period, all nests were sampled during the first flight survey, as done in previous years, but prior to a second flight survey, a one-sample equivalence test was conducted to determine the sample size necessary to provide a 95% confidence interval at 95% power (Castelloe 2000). As many active nests as logistically feasible were then revisited during the second flight survey while ensuring a minimum subsample was achieved. Nests in which complete production data were obtained were used to estimate, with 95% confidence, the number of young produced from all active nests. Prior to 2004, the percentage of known active nests in which production was not determined within the same nesting season was considered minimal (< 3%; Louisiana Department of Wildlife and Fisheries 2005). For each year from 2004 to 2008, we used PROC MEANS (SAS Institute Inc. 2011) to estimate, with 95% confidence, the mean number of young produced per active nests with known outcomes. We then multiplied means by the total number of active nests within that nesting season in order to estimate the total young produced annually from 2004–2008. We used general linear mixed models (PROC GLIMMIX; SAS Institute Inc. 2011) to examine the annual rate of change in (1) numbers of active nests, (2) numbers of successful nests, (3) numbers of young produced, (4) nest success, (5) productivity, and (6) brood size. Sample sizes of nests were small when surveys were initiated and increased throughout the monitoring period; thus, we weighted models for active nests, successful nests, and number of young produced by their total for each year, nest success and productivity by the number of active nests, and brood size by the number of successful nests. We used inclusion of intercept-only (e.g., null model), temporal linear, and temporal quadratic curvilinear models to test whether rates had changed over the monitoring period and if so, whether that change was consistent or variable. We evaluated candidate canonical links and distributions for each type of response variable (e.g., gamma, Gaussian, Poisson for count data, and binomial for 0/1 data). Selection of a distribution and model was based on Akaike’s information criteria, corrected for sample size (AICc), where distributions and models that best supported the data had the lowest AICc (Burnham and Anderson 2002). We evaluated goodness-of-fit of a model by comparing model ΔAICc to that of the intercept-only model. This procedure was followed because of the lack of application of traditional goodness-of-fit methods like R2, which are not applicable due to the use of pseudo-likelihoods in calculating generalized mixed models (Bolker et al. 2009, Liu et al. 2008). Southeastern Naturalist 15 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 Results From 1975 to 2008, the number of known active nests increased exponentially from 7 to 387 (Fig. 1; Tables 1, 2), exhibiting a mean annual rate of increase of 11.1 ± 0.3% per year. As numbers of known active nests increased, locations of nests expanded from 3 parishes (Terrebonne, Jefferson, and St. Charles) to 38 parishes throughout Louisiana; however, the majority of nests still occurs in the region surrounding the 3 original parishes (Fig. 2). Numbers of successful nests and total Figure 1. Numbers of known active nests, successful nests and total young produced by Louisiana Bald Eagles from 1975 to 2008 with fitted exponential models weighted by sample size (active nests = e(0.111*Year - 217.41), successful nests = e(0.098*Year - 190.85), and total young produced = e(0.114*Year - 222.10) ). Figure 2. Numbers of known active nests by parish in Louisiana in 1975 and 2008. Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 16 young produced increased exponentially (Table 2) at relatively similar rates as for active nests, respectively (9.8 ± 0.5% and 11.4 ± 0.3%; Fig. 1). Quadratic models, which suggest a change in the rate of increase over the monitoring period, were the next best-fitting models for active nests, successful nests, and total young produced, having 26.1, 41.7, and 24.0% probability, respectively, of being the bestfitting model among the models considered (Table 2). Table 1. Summary of Bald Eagle nesting in Louisiana from 1975 to 2008. Total Active Successful young Mean Year nests nests producedA Nest success Productivity brood size 1975 7 5 6 0.71 0.86 1.20 1976 10 6 8 0.60 0.80 1.33 1977 9 7 10 0.78 1.11 1.43 1978 12 7 10 0.58 0.83 1.43 1979 14 11 12 0.79 0.86 1.09 1980 14 12 17 0.86 1.21 1.42 1981 17 11 18 0.65 1.06 1.64 1982 13 12 17 0.92 1.31 1.42 1983 17 15 21 0.94 1.31 1.40 1984 16 12 18 0.75 1.13 1.50 1985 18 14 22 0.78 1.22 1.57 1986 28 22 37 0.79 1.32 1.68 1987 33 29 49 0.88 1.48 1.69 1988 28 23 39 0.82 1.39 1.70 1989 31 20 36 0.67 1.20 1.80 1990 42 35 55 0.83 1.31 1.57 1991 40 35 54 0.88 1.35 1.54 1992 53 50 88 0.94 1.66 1.76 1993 79 66 96 0.84 1.22 1.45 1994 90 71 131 0.79 1.46 1.85 1995 104 88 156 0.85 1.51 1.77 1996 102 89 155 0.88 1.53 1.74 1997 123 102 166 0.83 1.35 1.63 1998 137 105 158 0.78 1.17 1.50 1999 145 125 197 0.89 1.40 1.58 2000 152 129 213 0.85 1.41 1.65 2001 171 126 208 0.86 1.41 1.65 2002 178 148 238 0.88 1.41 1.61 2003 227 177 297 0.80 1.34 1.68 2004 235 165 314 ± 26 0.81 1.34 1.65 2005 255 149 355 ± 28 0.86 1.39 1.62 2006 283 167 435 ± 28 0.91 1.54 1.69 2007 336 265 465 ± 28 0.86 1.38 1.60 2008 387 266 530 ± 33 0.84 1.37 1.62 AFrom 2004 to 2008, production could not be determined for 20.9% of active nests (n = 1946); thus, a subsample of nests were used to estimate, with 95% confidence, total young produced. Prior to 2004, the number of active nests in which production could not be determined was minimal (2.6%, n = 1901); therefore, total young produced was considered an actual count. Southeastern Naturalist 17 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 Nest success increased slowly over the monitoring period (1.8 ± 0.8%; Fig. 3). Model selection using AICc showed that nest success was best described using a linear model with the next best-fitting model being the quadratic model, having 38.2% probability of being the best-fitting model among the models considered (Table 2). Productivity and brood size were best described using quadratic models, accounting for 92.8% and 79.7% of their Akaike model weights (Table 2). Modeled productivity increased from 0.96 until peaking in 2000 at 1.42 (Fig. 3) during which time the annual growth rate never exceeded 3.1%. Likewise, modeled brood size increased from 1.33 until peaking at 1.66 in 1999, after which it began to slowly decrease (Fig. 3). During the first two-thirds of the monitoring period annual production varied widely, becoming relatively more stable around 1999. Table 2. Comparison of intercept only, linear (Year), and quadratic curvilinear (Year2) generalized linear mixed models for active nests, successful nests, total young produced, nest success, productivity, and brood size of Louisiana Bald Eagles from 1975–2008, including number of parameters (K), Akaike’s Information Criterion adjusted for small sample size (AICc), difference between the AICc of the given model and the model with the lowest AICc (ΔAICc), and Akaike’s model weight (wi). Model distribution and canonical link function is given for each model. Model – distribution, canonical link function K AICc ΔAICc wi Active-nest models – Poisson, log Year 3 72.78 0.00 0.739 Year2 4 74.86 2.08 0.261 Intercept only 2 646.64 573.86 0.000 Successful-nest models – Poisson, log Year 3 95.36 0.00 0.583 Year2 4 96.03 0.67 0.417 Intercept only 2 482.19 386.83 0.000 Total-young-produced models – Poisson,l Year 3 81.96 0.00 0.760 Year2 4 84.26 2.30 0.240 Intercept only 2 876.06 794.10 0.000 Nest-success models – binomial, logit Year 3 179.49 0.00 0.564 Year2 4 180.27 0.78 0.382 Intercept only 2 184.19 4.70 0.054 Productivity models – gamma, log Year2 4 -35.61 0.00 0.928 Year 3 -30.03 5.58 0.057 Intercept only 2 -27.38 8.23 0.015 Brood-size models – gamma, log Year2 4 -45.97 0.00 0.797 Intercept only 2 -42.28 3.69 0.126 Year 3 -41.30 4.67 0.077 Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 18 Discussion Observed increases in nest success, productivity, and brood size in Louisiana were not as large as those reported in other studies (Grier 1982, Watts et al. 2008), wherein previous authors suggested that early increases in production resulted from reductions in human persecution and/or use of contaminants. These studies, however, did not control for increasing sample sizes, which may have resulted in larger changes in production estimates over time. Our findings of slight changes in production suggests that effects of reduced human persecution and contaminants may be less than previously assumed, or that nesting Bald Eagles in Louisiana may have been less affected by these factors. Production rates such as nest success, productivity, and brood size remained relatively constant in Texas from 1971 to 2005 (Saalfeld et al. 2009), despite rates of change for total number of active and successful nests and young produced being similar to those in Louisiana. Saalfeld Figure 3. Nest success, productivity, and brood size of Louisiana Bald Eagles from 1975 to 2008 with best-fitted models weighted by number of active or successful nests (solid lines) and 95% confidence intervals (dashed lines). Southeastern Naturalist 19 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 et al. (2009) speculated that the lack of change in Texas could have been due to the population being less effected by DDT than other regions or having recovered from its effects prior to 1971. Beyond contaminants and human persecution, other factors also likely influenced the relatively slow increase in production within Louisiana. Even if contaminants and human persecution affected the population early in the monitoring period, the increase in the population after the release from those negative effects were likely offset by other factors, such as expansion into new and possibly less than optimal nesting areas (Baldwin et al. 2012), changes in age structure and conspecific competition (Elliott et al. 2011), and even regular cyclic fluctuations (Mougeot et al. 2013). All of these factors together likely influenced production over the entire monitoring period, but further examination is required to better understand their individual effects. Less clear are the factors that potentially influenced the observed annual variation in production in Louisiana. Hurricanes destroyed a large proportion of nests in some winters but showed no substantial effect on production as affected nest sites often were rebuilt (Hess et al. 1994, Ortego et al. 2009). Other factors such as inclement winter weather and low prey availability may affect annual variation (Gende et al. 1997, Hansen 1987, Steidl et al. 1997), but these factors have not been investigated for Louisiana eagles. The small number of nests, especially in the earlier years, may have exacerbated annual fluctuations in production. During the monitoring period when there were fewer nests, averages would have been more susceptible to local factors affecting individuals and their nests, but as the population increased, averages would have better reflected landscape-l evel effects. The number of nesting Bald Eagles in Louisiana increased exponentially from precariously low numbers in 1975 to a minimum of 387 nesting pairs by 2008. Mean annual rates of increase for total active nests, successful nests, and young produced (11.1%, 9.8%, and 11.4%, respectively) in Louisiana are indicative of a healthy and expanding population (Buehler et al. 1991a). These increases are reflective of the general recovery of nesting Bald Eagles across much of the United States, as exhibited by other studies in different states and regions (Driscoll et al. 1999, Jenkins and Sherrod 2005, Nesbitt et al. 1990, Saalfeld et al. 2009, USFWS 2007, Watson et al. 2002, Watts et al. 2008). Similar to the many other Bald Eagle and raptor studies that use infrequent aerial surveys, there are inherent biases. For example, some of the increase in active nests observed over the progression of the monitoring period may be a result of increased observer expertise and discovery of existing but previously undocumented nests, as noted for other aerial nest surveys (Nesbitt et al. 1998, Saalfeld et al. 2009). In the same way, survey effort increased and expanded geographically as the number of nests increased and expanded. Nevertheless, we assumed that the number of nests not found each year was minimal and that by weighting our estimates by sample size, these biases would not affect our overall conclusions. Nest activity also may have been underestimated due to nesting not being initiated or nests being abandoned prior to a survey flight (Wilson et al. 2014). Likewise, Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 20 production of fledglings may have been overestimated (Nesbitt et al. 1998) because young in some nests, which were recorded as successful prior to actual fledging, may not have survived to depart from the nest. Furthermore, nests were excluded from production analyses if they had unknown outcomes, such as nests that were never surveyed when young were 8 weeks or older, or nests in which young would have been 8 weeks of age or older but no young were present regardless of whether they did not survive or they actually fledged. We believe that such production biases were minimal and our estimates are consistent among years, as argued by others (Nesbitt et al. 1998). Therefore, our survey results should represent a minimum estimate of nesting activity and are expected to reflect the general trend in production for the population. The Southeastern States Bald Eagle Recovery Plan (Murphy 1989) outlined goals for the southeastern region, which included Florida, Georgia, South Carolina, North Carolina, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Texas, and Louisiana. The plan considered that recovery was achieved when, along with documentation of population vigor and adequate habitat, a collective 3-year average of >0.9 young per active nest, >1.5 young per successful nest, and >50% of nests successful in raising at least one young was reached. The Louisiana population already exceeded goals for nest success and young produced per active nest when the recovery plan was first drafted in 1984; and the 3-year average for young produced per successful nest was >1.5 by 1986. The recovery plan also had an objective of 600 active nests distributed across at least 75% of their historical range, which represented approximately 40 nests in Louisiana. From 1992 to 1994, efforts were made to expand the Louisiana population in new areas using an eagle hacking program, as recommended in the Southeastern States Bald Eagle Recovery Plan (Murphy 1989); this was considered to be a successful technique in other states (see Jenkins and Sherrod 2005, Nesbitt et al. 1998). During these 3 nesting seasons, 33 eaglets were transported from nests in southern Louisiana to a hacking tower at Lake Ophelia National Wildlife Refuge in central Louisiana. A total of 32 young were successfully fledged from the hacking tower. A nest was found on the refuge in 1995, but unfortunately it was not determined whether any of the hacked eagles ever established nesting territories in the area or if the rate of nesting population increase was greater in this area compared with surrounding areas. However, prior to the hacking program there were already >40 known active nests in Louisiana. Thus, the nesting population in Louisiana has exceeded all recovery criteria every year since 1990 (Table 1), and the Bald Eagle was removed from the list of threatened and endangered species in 2007 (USFWS 2007). After the delisting, LDWF ceased annual statewide aerial Bald Eagle surveys; however, the Endangered Species Act mandates continued monitoring after the delisting of any species. Accordingly, the USFWS developed a post-delisting management plan for the Bald Eagle population with a statistical goal of an 80% probability of detecting a 25% or greater change in the number of occupied nests when surveyed every 5 years (starting in 2009) over a 20-year period (USFWS Southeastern Naturalist 21 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 2009). The plan criteria for defining occupied nests are the same as those used to define active nests in the Louisiana survey. The plan design uses a dual-frame estimate with a list frame (list of known nests) and an area frame (set of survey plots) to estimate the continental population. Watts and Duerr (2010) expressed concerns about the adequacy of the dualframe approach if the list frame is not properly maintained. Decreased priority in nest monitoring by states would cause deterioration in the list frame, which could degrade the viability of the dual-frame approach, specifically in the latter stages of this monitoring plan. However, continued maintenance of the list frame is costly, whereas the dual-frame approach was developed with consideration for cost and logistics. Sauer et al. (2011) suggest that the dual-frame approach is still more effective and logistically feasible than an area-only sample and also encourages maintenance of the nest list. Accordingly, wildlife managers in Louisiana and elsewhere may want to consider updating nest-list frames through periodic statewide aerial surveys during post-delisting monitoring. An alternative option would be to incorporate a citizenbased nest-reporting system to enhance the list frame between post-delisting monitoring surveys. This approach would allow for the addition of new nests to the nest list and provide an update on the status of existing nests. Several states (e.g., Colorado, Iowa, Texas, New Jersey, Pennsylvania) use citizen-based reporting systems of various types, consisting of forms, online reporting, and notifying a local conservation officer (Gross and Brauning 2011, Smith and Clark 2012). A citizen-based nest-reporting system may be more cost effective than a statewide aerial survey but would require verification for each site and quality control to ensure that a nest is not recorded more than once. Likewise, there are many biases associated with citizen-based reporting (Dickinson et al. 2010); however, such an effort to maintain nest lists would be in line with the suggestions of a state-based effort for continued updating and management of the nest list as presented in the post-delisting monitoring plan (USFWS 2009) and Sauer et al. (2011). The Bald Eagle is listed as a species of conservation concern (shows evidence of or the potential for population decline) in Louisiana (Lester et al. 2005); however, this status may require periodic re-evaluation as the population grows. According to the Louisiana Comprehensive Wildlife Conservation Strategy (Lester et al. 2005), if the species were to be considered secure or apparently secure, referring to ≥100 nesting territories (M. Seymour, Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA, pers. comm.), it may no longer warrant conservation concern. A change in the state status may not endanger or inhibit the protection of Bald Eagles, their young, or their nests because these would still be afforded coverage under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. Long-term monitoring has documented the recovery of the Bald Eagle, and as of 2008, the increase of the nesting population has not slowed in Louisiana. However, the peaking of productivity and brood size in 2000 and 1999, respectively, along with the relatively high Akaike weights for many of the second best-fitting quadratic models suggests the increase in the nesting population may be slowing. Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 22 Future research examining regional population trends may reveal that the most populated region in southeastern Louisiana may be approaching or have reached local carrying capacity, which may favor dispersal and promote nesting in other regions of the state. Habitat loss and human development may be the most important limiting factors in the expansion of the Bald Eagle in Louisiana. As eagle numbers grew, so did Louisiana’s human population, which increased by about 25% from 1970 to 2010 (US Census Bureau 2010). In the past, human activity has been a strong predictor of Bald Eagle nest-site selection (Andrew and Mosher 1982, Buehler et al. 1991b, Saalfeld and Conway 2010). Eagles may select areas away from human activity to nest, but as populations expand they could alter their preferences and move into populated areas (Guinn 2013). In Florida and Chesapeake Bay, there has been no apparent effect on productivity for birds nesting in human-dominated settings (Millsap et al. 2004, Watts 2006). Thus, the continued stability and growth of the nesting population may depend on the ability of Bald Eagle’s to cope with human activity and the protection of current and future nesting habitats. Acknowledgments We dedicate this manuscript to the memory of Thomas Hess Jr., our co-author who devoted much of his career to the Bald Eagles of Louisiana. Financial support for this study and its publication were provided by the Louisiana Department of Wildlife and Fisheries and the US Fish and Wildlife Service, Division of Federal Aid, through Louisiana State Wildlife Grant T-98, the Rockefeller Wildlife Refuge Trust, the US Geological Survey-Louisiana Cooperative Fish and Wildlife Research Unit, and the School of Renewable Natural Resources at Louisiana State University. We acknowledge the work of W. Dubuc, R. Aycock, G. Melancon, J. Linscombe, and all the individuals from US Fish and Wildlife Service and Louisiana Department of Wildlife and Fisheries who assisted with Louisiana’s nest-monitoring program since 1975. We also thank the landowners who contributed information on nesting eagles. We appreciate W. Selman, D. Blouin, L. Wang, and 3 anonymous reviewers for providing critical comments on this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Literature Cited Andrew, J.M., and J.A. Mosher. 1982. Bald Eagle nest-site selection and nesting habitat in Maryland. Journal of Wildlife Management 46(2):382–390. Bailey, A.M. 1919. The Bald Eagle in Louisiana. The Wilson Bulletin 31(2):52–55. Baldwin, J.D., J.W. Bosley, L. Oberhofer, O.L. Bass, and B.K. Mealey. 2012. Long-term changes, 1958–2010, in the reproduction of Bald Eagles of Florida Bay, Southern Coastal Everglades. Journal of Raptor Research 46(4):336–348. Beyer, G.E. 1900. The avifauna of Louisiana, with an annotated list of the birds of the state. Proceedings Louisiana Academy of Naturalists for 1897–1899:75–120. Beyer, G.E., A. Allison, and H.H. Kopman. 1908. List of the birds of Louisiana. Part V. The Auk 25(4):439–448. Bolker, B.M., M.E. Brooks, C.J. Clark, S.W. Geange, J.R. Poulsen, M.H.H. Stevens, and J.-S.S. White. 2009. Generalized linear mixed models: A practical guide for ecology and evolution. Trends in Ecology and Evolution 24(3):127–135. Southeastern Naturalist 23 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 Buehler, D. A. 2000. Bald Eagle (Haliaeetus leucocephalus). No. 506, In A. Poole and F. Gill (Eds.). The Birds of North America The Birds of North America, Inc., Philadelphia, PA. Buehler, D.A., J.D. Fraser, J.K.D. Seegar, and G.D. Therres. 1991a. Survival rates and population dynamics of Bald Eagles on Chesapeake Bay. Journal of Wildlife Management 55(4):608–613. Buehler, D.A., T.J. Mersmann, J.D. Fraser, and J.K.D. Seegar. 1991b. Effects of human activity on Bald Eagle distribution on the Northern Chesapeake Bay. Journal of Wildlife Management 55(2):282–290. Burnham, K.P., and D.R. Anderson. 2002. Model Selection and Multimodel Inference: A Practical Information-theoretic Approach, Second Edition. Springer, New York, NY. 488 pp. Castelloe, J.M. 2000. Sample-size computations and power analysis with the SAS System. Paper 265–25, In Proceedings of the Twenty-fifth Annual SAS User’s Group International Conference. SAS Institute Inc., Cary, NC. Available online at http://www.ats.ucla. edu/stat/sas/library/powersamplesize.pdf. Dickinson, J.L., B. Zuckerberg, and D.N. Bonter. 2010. Citizen science as an ecological research tool: Challenges and benefits. Annual Review of Ecology, Evolution, and Systematics 41:149–172. Driscoll, D.E., R.E. Jackman, W.G. Hunt, G.L. Beatty, J.T. Driscoll, R.L. Glinski, T.A. Gatz, and R.I. Mesta. 1999. Status of nesting Bald Eagles in Arizona. Journal of Raptor Research 33(3):218–226. Elliott, K.H., J.E. Elliott, L.K. Wilson, I. Jones, and K. Stenerson. 2011. Density-dependence in the survival and reproduction of Bald Eagles: Linkages to Chum Salmon. Journal of Wildlife Management 75(8):1688–1699. Fraser, J.D., L.D. Frenzel, J.E. Mathisen, F. Martin, and M.E. Shough. 1983. Scheduling Bald Eagle reproduction surveys. Wildlife Society Bulletin 11(1):13–16. Gende, S.M., M.F. Wilson, and M. Jacobsen. 1997. Reproductive success of Bald Eagles (Haliaeetus leucocephalus) and its association with habitat or landscape features and weather in southeast Alaska. Canadian Journal of Zoology 75(10):1595–1604. Grier, J.W. 1982. Ban of DDT and subsequent recovery of reproduction in Bald Eagles. Science 218(4578):1232–1235. Grier, J.W., M.G. Jon, G.D. Hamilton, and P.A. Gray. 1981. Aerial-visibility bias and survey techniques for nesting Bald Eagles in northwestern Ontario. Journal of Wildlife Management 45(1):83–92. Gross, D.A., and D.W. Brauning. 2011. Bald Eagle management plan for Pennsylvania (2010–2019). Bureau of Wildlife Management, Pennsylvania Game Commission, Harrisburg, PA. Guinn, J.E. 2013. Generational habituation and current Bald Eagle populations. Human- Wildlife Interactions 7(1):69–76. Hansen, A.J. 1987. Regulation of Bald Eagle reproductive rates in southeast Alaska. Ecology 68(5):1387–1392. Hess, T J., W.G. Perry, and W. Dubuc. 1994. Effects of Hurricane Andrew on Louisiana's nesting Bald Eagles. Proceedings of the Annual Conference Southeastern Association of Fish and Wildlife Agencies 48:395–400. Jenkins, M.A., and S.K. Sherrod. 2005. Growth and recovery of the Bald Eagle population in Oklahoma. Wildlife Society Bulletin 33(3):810–813. Lester, G.H., S.G. Sorensen, P.L. Faulkner, C.S. Reid, and I.E. Maxit. 2005. Louisiana comprehensive wildlife conservation strategy. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA. Southeastern Naturalist N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 24 Liu, H., Y. Zheng, and J. Shen. 2008. Goodness-of-fit measures of R2 for repeated measures mixed-effect models. Journal of Applied Statistics 35(10):1081–1092. Louisiana Department of Wildlife and Fisheries. 2005. Louisiana Bald Eagle program status report for 2004–2005. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA. Lowery, G.H., Jr. 1974. Louisiana Birds. Louisiana State University Press, Baton Rouge, LA. 651 pp. Millsap, B., T. Breen, E. McConnell, T. Steffer, L. Phillips, N. Douglass, and S. Taylor. 2004. Comparative fecundity and survival of Bald Eagles fledged from suburban and rural natal areas in Florida. Journal of Wildlife Management 68(4):1018–1031. Mougeot, F., J. Gerrard, E. Dzus, B. Arroyo, P.N. Gerrard, C. Dzus, and G. Bortolotti. 2013. Population trends and reproduction of Bald Eagles at Besnard Lake, Saskatchewan, Canada 1968–2012. Journal of Raptor Research 47(2):96–107. Murphy, T.M. 1989. Southeastern states Bald Eagle recovery plan. US Fish and Wildlife Service, Atlanta, GA. Nesbitt, S.A., G.L. Holder, D.A. Mager, and S.T. Schwikert. 1990. Use of aerial surveys to evaluate Bald Eagle nesting in Florida. Proceedings of the Southeast Raptor Management Symposium and Workshop 14:207–210. Nesbitt, S.A., M.A. Jenkins, S.K. Sherrod, D.A. Wood, A. Beske, J.H. White, P.A. Schulz, and S.T. Schwikert. 1998. Recent status of Florida’s Bald Eagle population and its role in eagle reestablishment efforts in the southeastern United States. Proceedings of the Annual Conference Southeastern Association of Fish and Wildlife Agencies 52:377–383. Ortego, B., C. Gregory, D. Mabie, M. Mitchell, and D. Schmidt. 2009. Texas Bald Eagle. Bulletin of the Texas Ornithological Society 42:1–17. Payne, G.C. 1975. Observations on southern Bald Eagle nesting in southern Louisiana. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA. Status Report 16. Saalfeld, S.T., and W.C. Conway. 2010. Local and landscape habitat selection of nesting Bald Eagles in East Texas. Southeastern Naturalist 9(4):731–742. Saalfeld, S.T., W.C. Conway, R. Maxey, C. Gregory, and B. Ortego. 2009. Recovery of nesting Bald Eagles in Texas. Southeastern Naturalist 8(1):83–92. SAS Institute Inc. 2011. SAS/STAT User’s Guide, 9.3 Edition. Cary, NC. Sauer, J.R., M.C. Otto, W.L. Kendall, and G.S. Zimmerman. 2011. Monitoring Bald Eagles using lists of nests: Response to Watts and Duerr. Journal of Wildlife Management 75(3):509–512. Smith, L., and K.E. Clark. 2012. New Jersey Bald Eagle project, 2012. New Jersey Department of Environmental Protection, Division of Fish and Wildlife, Trenton, NJ. Sprunt, A., IV, and F.J. Ligas. 1964. Excerpts from convention addresses on the 1963 Bald Eagle count. Audubon Magazine 66(1):45–47. Steidl, R.J., K.D. Kozie, and R.G. Anthony. 1997. Reproductive success of Bald Eagles in Interior Alaska. Journal of Wildlife Management 61(4):1313–1321. US Census Bureau. 2010. 2010 Census: Louisiana profile. Available online at http://www2. Accessed 6 July 2013. US Fish and Wildlife Service (USFWS). 1978. Endangered and threatened wildlife and plants: Determination of certain Bald Eagle populations as endagered or threatened, final rule. Federal Register 43:6230–6233. USFWS. 2007. Endangered and threatened wildlife and plants: Removing the Bald Eagle in the lower 48 states from the list of endangered and threatened wildlife, final rule. Federal Register 72:37,346–37,372. Southeastern Naturalist 25 N.R. Smith, T.J. Hess Jr., and A.D. Afton 2016 Vol. 15, No. 1 USFWS. 2009. Post-delisting monitoring plan for the Bald Eagle (Haliaeetus leucocephalus) in the contiguous 48 states. Divisions of Endangered Species and Migratory Birds and State Programs, Midwest Regional Office, Twin Cities, MN. Watson, J.W. 1993. Responses of nesting Bald Eagles to helicopter surveys. Wildlife Society Bulletin 21(2):171–178. Watson, J.W., D. Stinson, K.R. McAllister, and T.E. Owens. 2002. Population status of Bald Eagles breeding in Washington at the end of the 20th century. Journal of Raptor Research 36(3):161–169. Watts, B.D. 2006. Evaluation of biological benefits and social consequences of Bald Eagle protection standards in Virginia. Center for Conservation Biology, College of William and Mary, Williamsburg, VA. Technical Report Series CCBTR-06-09:28. Watts, B.D., and A.E. Duerr. 2010. Nest turnover rates and list-frame decay in Bald Eagles: Implications for the national monitoring plan. Journal of Wildlife Management 74(5):940–944. Watts, B.D., G.D. Therres, and M.A. Byrd. 2008. Recovery of the Chesapeake Bay Bald Eagle nesting population. Journal of Wildlife Management 72(1):152–158. Wilson, T.L., J.H. Schmidt, W.L. Thompson, and L.M. Phillips. 2014. Using double-observer aerial surveys to monitor nesting Bald Eagles in Alaska: Are all nests available for detection? Journal of Wildlife Management 78(6):1096–1103.