The Reliability of Brood Patches in Assessing Reproductive Status in the Marbled Murrelet: Words of Caution

Tranquilla, Laura A. McFarlane; Bradley, Russell W.; Lank, David B.; Williams, Tony; Lougheed, Lynn W.; Cooke, Fred

doi:10.1675/1524-4695(2003)026[0108:trobpi]2.0.co;2

Cited by 18 publications

(15 citation statements)

References 28 publications

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“…Potential breeders (n = 12) were birds that did not initiate nesting but were physiologically in breeding condition at the time of capture. Physiological characteristics indicating breeding were (1) the presence of a brood patch, which can be developed in both sexes (McFarlane-Tranquilla et al 2003a), and (2) elevated plasma calcium or vitellogenin concentrations; Peery et al (2004b) described criteria for determining if calcium and vitellogenin levels are elevated. Nonbreeders (n = 11) were birds that did not initiate nesting and were not in breeding condition at the time of capture.…”

Section: Meeting Reproductive Demands In a Dynamic Upwelling System: mentioning

confidence: 99%

Meeting Reproductive Demands in a Dynamic Upwelling System: Foraging Strategies of a Pursuit-Diving Seabird, the Marbled Murrelet

Peery¹,

Newman²,

Storlazzi³

et al. 2009

Condor

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Resumen. Las aves marinas mantienen una plasticidad en sus comportamientos de forrajeo para poder con las demandas energéticas y las restricciones de forrajeo que varían durante el ciclo reproductivo. Sin embargo, los estudios sobre comportamiento que comparan individuos reproductivos y no reproductivos son raros. Aquí caracterizamos cómo los individuos de la especie Brachyramphus marmoratus ajustan sus esfuerzos de forrajeo en respuesta a sus demandas reproductivas en un sistema de surgencias marinas en el centro de California. Marcamos 32 individuos, de quienes conocíamos su estado reproductivo, usando radiotransmisores (9 en reproducción, 12 reproductores potenciales y 11 no reproductivos) y estimamos tanto las áreas de forrajeo como las tasas de buceo durante la época reproductiva. Los individuos de B. marmoratus permanecieron más tiempo buceando durante los periodos de surgencia que durante los periodos de relajación oceanográfica, aumentaron su área de forrajeo con el aumento del tiempo del periodo de relajación y redujeron sus áreas de forrajeo después de la transición al periodo de surgencias. Cuando los individuos no se encontraban incubando, se movieron siguiendo un patrón circadiano, permaneciendo durantes las horas de descanso nocturnas cerca de las rutas de vuelo que utilizan para alcanzar el hábitat de anidación y forrajeo durante el día, las que en promedio se encontraron a 5.7 km (DE 6.7 km) de las localidades de reposo nocturno. Las aves en fase reproductiva forrajearon más cerca de las áreas de anidación una vez que iniciaron la anidación y cuando la atención a los polluelos fue máxima, y luego volvieron a viajar distancias mayores una vez terminado el periodo de anidación. Las aves en fase no reproductiva presentaron distribuciones diurnas y nocturnas similares y tendieron a localizarse más lejos de las rutas de vuelo tierra adentro. Las aves en fase reproductiva aumentaron en un 71-73% el tiempo que permanecieron buceando cuando estas tenían un nido activo, aumentando el número de zambullidos sin aumentar la frecuencia de anaerobiosis. Así, para alcanzar las demandas reproductivas durante la anidación, los individuos de B. marmoratus adoptaron una estrategia mixta en que redujeron el gasto de engría de los vuelos hacia los sitios de forrajeo y aumentaron las tasas de zambullidos aeróbicos.Abstract. Seabirds maintain plasticity in their foraging behavior to cope with energy demands and foraging constraints that vary over the reproductive cycle, but behavioral studies comparing breeding and nonbreeding individuals are rare. here we characterize how Marbled Murrelets (Brachyramphus marmoratus) adjust their foraging effort in response to changes in reproductive demands in an upwelling system in central California. we radio-marked 32 murrelets of known reproductive status (9 breeders, 12 potential breeders, and 11 nonbreeders) and estimated both foraging ranges and diving rates during the breeding season. Murrelets spent more time diving during upwelling than oceanographic relaxation, increased the...

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Section: Meeting Reproductive Demands In a Dynamic Upwelling System: mentioning

confidence: 99%

Meeting Reproductive Demands in a Dynamic Upwelling System: Foraging Strategies of a Pursuit-Diving Seabird, the Marbled Murrelet

Peery¹,

Newman²,

Storlazzi³

et al. 2009

Condor

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“…Similarly, elevated VTG levels in female murrelets only indicate that a bird is producing an egg, not necessarily that an egg is laid (McFarlane Tranquilla et al 2003b). Although both of these methods may indicate reproductive maturity and perhaps even intention to breed, neither is a reliable indicator of actual egg laying or nest initiation (McFarlane Tranquilla et al 2003a). Therefore, it is likely that we overestimated the number of potential breeders in our sample.…”

Section: Discussionmentioning

confidence: 96%

“…We categorized these individuals as ''potential breeders,'' but we recognize that using brood patch scores and VTG as measures of breeding condition has limitations. The presence of a brood patch only signifies that some of the hormonal changes associated with breeding have occurred and does not necessarily indicate that a murrelet has initiated egg development or incubation (McFarlane Tranquilla et al 2003a). In Marbled Murrelets, McFarlane Tranquilla et al (2003a found that brood patch development can occur quickly or can take weeks to complete.…”

Section: Discussionmentioning

confidence: 99%

“…BP ¼ 1-5; Sealy 1974) at the time of capture as ''potential breeders'' and those without a brood patch (i.e. BP ¼ 0, 6) as ''nonbreeders'' (McFarlane Tranquilla et al 2003a, Peery et al 2004b.…”

Section: Data Analysesmentioning

confidence: 99%

“…Vitellogenin is an egg-yolk protein that becomes elevated in the plasma of female birds during egg production and has been used successfully as an indicator of breeding status in Marbled Murrelets (Vanderkist et al 2000, Lougheed et al 2002, McFarlane Tranquilla et al 2003a, 2003b, Peery et al 2004b, Janssen et al 2009). We measured levels of vitellogenic zinc as an index to plasma VTG and used the threshold validated for Marbled Murrelet (0.96 lg mL À1 ) to distinguish potential breeders (Vanderkist et al 2000, McFarlane Tranquilla et al 2003b.…”

Section: Data Analysesmentioning

confidence: 99%

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The Condor

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Low breeding propensity and wide‐ranging movements by marbled murrelets in Washington

et al. 2016

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The marbled murrelet (Brachyramphus marmoratus) is a threatened seabird that forages in nearshore marine waters but nests inland, commonly in older coniferous forests. Information on ranging behavior and breeding propensity can be useful for informing management, especially when comparisons can be made between declining or threatened populations and more stable, unthreatened populations. Over 5 years, we measured ranging behavior and breeding propensity of marbled murrelets in Washington, USA where murrelets are considered threatened. Our primary objective was to compare space use and breeding by murrelets in Washington with those from other regions and where the species is not considered threatened. We radio tracked 157 murrelets from 2004 to 2008. Median marine 95% kernel ranges were 487 km2 (truex¯=938±1,348 [SD]) and larger than those reported for non‐threatened populations in Alaska, USA in other studies. Ranges computed from minimum convex polygons (MCPs; median = 404 km2; truex¯=708±847) were on average similar to those reported for threatened populations in California, USA, although larger than those reported for Alaska. Distances traveled between consecutive marine telemetry locations were greater than reported previously in Alaska. Variation in movements in our study were not associated with oceanographic conditions although appeared greater for murrelets captured along the Pacific Coast compared to those occupying interior marine waters in the Salish Sea. Twenty individuals (12.7%) attempted to breed in our study, and we estimated breeding propensity was 13.1–20.0%. This is the lowest breeding propensity reported for a population of murrelets to date. For breeders, nest‐sea commuting distances were greater than reported previously, with 4 breeders traveling farther than the previously reported maximum of 125 km. The low breeding propensity, large marine ranges, and long nest‐sea commutes in this study may point to poor‐quality marine habitat in Washington compared to other parts of the murrelet's range. In combination with reported declines in terrestrial nesting habitat from other studies, this indicates that additional management is needed to improve murrelet breeding habitat in Washington. Future management actions should focus on improving both terrestrial and marine habitat. © 2016 The Wildlife Society.

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The Reliability of Brood Patches in Assessing Reproductive Status in the Marbled Murrelet: Words of Caution

Cited by 18 publications

References 28 publications

Meeting Reproductive Demands in a Dynamic Upwelling System: Foraging Strategies of a Pursuit-Diving Seabird, the Marbled Murrelet

Meeting Reproductive Demands in a Dynamic Upwelling System: Foraging Strategies of a Pursuit-Diving Seabird, the Marbled Murrelet

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Low breeding propensity and wide‐ranging movements by marbled murrelets in Washington

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