Influence of nesting Bald Eagles (Haliaeetus leucocephalus) on Common Loon (Gavia immer) occupancy and productivity in New Hampshire

Cooley, John H.; Harris, David R.; Johnson, Vanessa S.; Martin, Christian J.

doi:10.1676/18-75

Cited by 4 publications

(2 citation statements)

References 33 publications

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“…Bald Eagles at Voyageurs National Park preyed on Common Loon eggs (Windels et al 2013) but had non-significant effects on the survival of Common Loon chicks. Similarly, in New Hampshire, predation by Bald Eagles on Common Loons did not translate to declines in the adult population (Cooley et al 2019). Bald Eagles affected other piscivorous birds, including Ospreys, Great Blue Herons, and Double-crested Cormorants, at Voyageurs National Park via multiple direct and pathways, likely explain why these latter species declined, whereas Common Loons did not appear to (Windels 2016, Cruz et al 2019).…”

Section: Discussionmentioning

confidence: 94%

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Survival of Common Loon chicks appears unaffected by Bald Eagle recovery in northern Minnesota

Cruz¹,

Windels²,

Thogmartin³

et al. 2023

ACE

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Recovering species are not returning to the same environments or communities from which they disappeared. Conservation researchers and practitioners are thus faced with additional challenges in ensuring species resilience in these rapidly changing ecosystems. Assessing the resilience of species in these novel systems can still be guided by species' ecology, including knowledge of their population size, life history traits, and behavioral adaptations, as well as the type, strength, and number of ways that they interact with other species in the community. We summarized broad trends of Common Loons (Gavia immer) breeding at Voyageurs National Park from 1973 to 2009, and evaluated the effects of increased risk from recovering Bald Eagles (Haliaeetus leucocephalus) on chick survival from 2004 to 2006. Adult Common Loons appear to have increased over time. Using Bayesian survival models that accounted for imperfect detection of unmarked individuals, we determined that chick survival of Common Loons was high from year to year and was unrelated to predation risk from Bald Eagles because chicks in territories closer to active nests did not experience greater mortality than those farther away. We suggest that Common Loon chicks were unaffected by the recovery of this top predator during the three years of sampling. Previous research indicates that Bald Eagles and other predators are an important source of egg losses, but Common Loons can compensate by re-nesting. Despite current uncertainties from anthropogenic threats, knowledge of a species' ecology remains instrumental in determining its resilience during recovery. La survie des poussins du Plongeon huard ne semble pas affectée par le rétablissement du Pygargue à tête blanche dans le nord du MinnesotaRÉSUMÉ. Les espèces en voie de rétablissement ne reviennent pas dans les mêmes environnements ou communautés d'où elles ont disparu. Les chercheurs et les praticiens de la conservation sont donc confrontés à des défis supplémentaires pour assurer la résilience des espèces dans ces écosystèmes en évolution rapide. L'évaluation de la résilience des espèces dans ces nouveaux systèmes peut encore être guidée par l'écologie des espèces, y compris la connaissance de la taille de leur population, de leurs composantes biodémographiques et de leurs adaptations comportementales, et aussi par le type, la force et le nombre de façons dont elles interagissent avec d'autres espèces de la communauté. Nous avons colligé les tendances générales de la reproduction du Plongeon huard (Gavia immer) au parc national des Voyageurs de 1973 à 2009, et évalué les effets du risque accru de prédation par les Pygargues à tête blanche (Haliaeetus leucocephalus) en voie de rétablissement sur la survie des poussins de 2004 à 2006. Le nombre de plongeons adultes semble avoir augmenté au fil des années. Au moyen de modèles de survie bayésiens qui tenaient compte de la détection imparfaite des individus non marqués, nous avons déterminé que la survie des poussins du Plongeon huard était élevée d'une année à...

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Section: Discussionmentioning

confidence: 94%

“…), gulls (Larus spp. ), raccoons (Procyon lotor), American mink (Neogale vison), and fishers (Pekania pennanti; Windels et al 2013, Cooley et al 2019. Chicks are semi-precocial, leaving the nest about a day after hatching but remaining dependent on their parents for food for a pre-fledging period of about six weeks (Barr 1996).…”

Section: Introductionmentioning

confidence: 99%

Survival of Common Loon chicks appears unaffected by Bald Eagle recovery in northern Minnesota

Cruz¹,

Windels²,

Thogmartin³

et al. 2023

ACE

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Drivers of declines in common loon (Gavia immer) productivity in Ontario, Canada

Bianchini

Tozer

Alvo³

et al. 2020

Science of The Total Environment

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Plunging floater survival causes cryptic population decline in the Common Loon

et al. 2020

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Populations of many vertebrates are declining and geographic ranges contracting, largely as a consequence of anthropogenic threats. Many reports of such decline, however, lack the breadth and detail to narrow down its causes. Here we describe population decline in the Common Loon (Gavia immer), a charismatic aquatic bird, based on systematic resighting and measurement of a marked population. During our 27-year investigation, age-adjusted chick mass has fallen by 11%, mortality among young and old chicks has increased by 31% and 82%, respectively, and fledging success has declined by 26%. Meanwhile, the return rate of marked nonbreeders (“floaters”) has plunged by 53%, and the adult population overall has declined by 22%. Consistent with the thinning ranks of floaters, the rate of territory eviction has decreased by 52% during the study. Despite the decline in floaters, territory occupancy remains unchanged. However, a matrix model, updated with recent estimates for breeding success, juvenile survival, and senescence, yields a recalculated deterministic population growth rate (λ) of 0.94 for our study population, which suggests that declines in vital rates could lead to a loss of 52% of the current population and a decline of 37% in territory occupancy by 2031. Lack of data on floaters in other upper Midwest and New England loon populations leaves their status in doubt.

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Influence of nesting Bald Eagles (Haliaeetus leucocephalus) on Common Loon (Gavia immer) occupancy and productivity in New Hampshire

Cited by 4 publications

References 33 publications

Survival of Common Loon chicks appears unaffected by Bald Eagle recovery in northern Minnesota

Survival of Common Loon chicks appears unaffected by Bald Eagle recovery in northern Minnesota

Drivers of declines in common loon (Gavia immer) productivity in Ontario, Canada

Plunging floater survival causes cryptic population decline in the Common Loon

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