Morphometric Determination of Gender in Adult Humboldt Penguins (Spheniscus humboldti  )

Wallace, Roberta S.; Dubach, Jean; Michaels, Margaret; Keuler, Nicholas S.; Diebold, Edward D.; Grzybowski, Karen; Teare, J. Andrew; Willis, Mary Jo

doi:10.1675/1524-4695-31.3.448

Cited by 13 publications

(11 citation statements)

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“…We used a logistic regression to develop the morphometric sex identification model (Rodriguez et al , Gill and Vonhof , Wallace et al ). We randomly chose 80% of the data ( n = 346) to use as a training data set to build potential models (Rodriguez et al , Reynolds et al ).…”

Section: Methodsmentioning

confidence: 99%

“…Accurate sexual determination is important in understanding common questions of population ecology, including sex ratios in a breeding population, differential mortality, behavioral studies (e.g., male or female incubation behavior), differential habitat selection, and sex‐specific demographics (Iko et al , Gill and Vonhof , Wallace et al ). These topics are difficult to study in the greater roadrunner ( Geococcyx californianus; roadrunner) because of their sexually monomorphic plumage.…”

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confidence: 99%

“…Birds can be sexed through linear models that classify birds based on small, but significant, differences in biometric measurements (Iko et al , Gill and Vonhof ). This method of morphometric sex identification is easy, inexpensive, non‐invasive (Wallace et al ), and has been successfully used with bird species from diverse ecosystems (Rodriguez et al , Gill and Vonhof , Herring et al ).…”

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confidence: 99%

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A morphometric sex determination model for adult greater roadrunners (Geococcyx californianus)

et al. 2014

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Little is known of the greater roadrunner's (Geococcyx californianus; roadrunner) ecology and many demographic questions are difficult to answer because of our inability to determine adult bird sex in the field. We collected measurements from live-captured roadrunners of known sex in Fisher County, Texas, USA, and from roadrunner specimens from museums and university biological collections from 2003 to 2012 to develop a predictive logistic regression model for adult sex determination. We measured 433 adult birds of which 80% (n ¼ 346) were randomly chosen to build potential models. Our best model included the variable estimate bill depth, which was found to be larger in males and correctly classified 80% of the birds. We validated the model with the remaining 20% of measurements (n ¼ 87) and correctly identified the sex of 85% of the birds. Because this model incorporated roadrunners from across their range, it provides an easy, inexpensive, accurate, and field-relevant methodology for sex determination of adult roadrunners at the point of capture. Ó 2014 The Wildlife Society.

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Section: Methodsmentioning

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A morphometric sex determination model for adult greater roadrunners (Geococcyx californianus)

et al. 2014

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“…Although age and breeding experience of the study birds was unknown, we assumed that they were residents in the breeding colony. After capture, the penguins were at first masked to reduce stress levels, and then bill depth and length measured to determine their sex (Bertellotti et al, 2002;Vanstreels et al, 2011;Wallace et al, 2008).…”

Section: Field Workmentioning

confidence: 99%

Post-moult movements of sympatrically breeding Humboldt and Magellanic Penguins in south-central Chile

Pütz¹,

Rey

Hiriart‐Bertrand³

et al. 2016

Global Ecology and Conservation

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a b s t r a c tTen Humboldt (Spheniscus humboldti) and eight Magellanic Penguins (S. magellanicus) were successfully equipped with satellite transmitters in March 2009 on Islotes Puñihuil in central south-Chile to follow their post-moult dispersal. Overall, Humboldt Penguins could be followed for a mean period of 49 ±18 days (range: 25-93) and Magellanic Penguins for 57 ±12 days (range 35-68). Irrespective of species and sex, seven study birds remained in the vicinity of their breeding ground throughout the transmission period. All other penguins moved northwards, either only a relatively short distance (max 400 km) to Isla Mocha at 38°S (n = 3) or further north beyond 35°S (n = 8). However, eight of these birds (73%) turned south again towards the end of the individual tracking periods. The total area used by both species during the tracking period was restricted to a coastal area stretching from the breeding site at 42°S about 1000 km to the north at about 32°S. The area used by Humboldt penguins overlapped by 95% the area used by Magellanic penguins, whereas the area used by the latter species was much larger and overlapped only by 45% with the area used by Humboldt penguins. Overall, our results indicate that Magellanic Penguins in the Pacific Ocean are probably less migratory than their conspecifics on the Atlantic side, while Humboldt Penguins appear to be more migratory than previously anticipated. In general, there was a poor relationship between preferred foraging areas and chlorophyll-a, as a proxy for primary productivity, indicating the limitations of using remote-sensed primary productivity as a proxy to interpret the foraging behaviour of marine predators. In addition, there was also no clear relationship between the preferred foraging areas and the amount of regional fish catches by artisanal fishery.

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“…Information theoretics has not often been used for shape and size data (see Wallace et al, 2008 for two examples with size). For comparison with our information-theoretics approach, we also performed a more traditional a posteriori analyses, using multivariate analysis of variance (MANOVA), in which we would have rejected the null hypothesis that bill shapes were the same for titmice from ranges of the three different juniper tree species, at least along several EES axes (above view, ES3 and ES4; portrait view, ES5; profile view, ES4; each MANOVA test, F 2,131 > 5.78, P < 0.004).…”

Section: Geographical Variation In Bill Shapementioning

confidence: 99%

Fitting the bill: do different winter food resources influence juniper titmouse (Baeolophus ridgwayi) bill morphology?

Francis

Guralnick

2010

Biological Journal of the Linnean Society

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Divergent adaptive selection is a prominent mechanism influencing patterns of morphological diversity. We used the juniper titmouse [Baeolophus ridgwayi (Richmond, 1902)], a nonmigratory passerine that inhabits woodlands throughout western North America, to investigate variation in bill morphology in relation to diet and geography. We gathered data from museum specimens and used morphometric techniques to determine the relative strength of support for competing hypotheses using information theoretics: (1) differences in bill morphology are predicted by a key winter food resource that each regional population consumes (seeds of different juniper tree species); or (2) bill morphology scales with body size, and both increase along a latitudinal gradient. Juniper species emerged as the variable with the most support explaining variation in bill size, supporting the hypothesis that seed sizes influence bill size, independently of body size. The shape analysis revealed no distinct patterns in bill shape variation, but employed a powerful method for evaluating the strength of support for numerous candidate models. The differences in bill size of juniper titmice across their range are likely to reflect adaptive variation, because bill morphology is highly heritable in birds, juniper titmouse gene flow appears to be relatively low, and there is a clear mechanistic explanation for why bill sizes may differ among the ranges of the three juniper species.

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Morphometric Determination of Gender in Adult Humboldt Penguins (Spheniscus humboldti )

Cited by 13 publications

References 10 publications

A morphometric sex determination model for adult greater roadrunners (Geococcyx californianus)

A morphometric sex determination model for adult greater roadrunners (Geococcyx californianus)

Post-moult movements of sympatrically breeding Humboldt and Magellanic Penguins in south-central Chile

Fitting the bill: do different winter food resources influence juniper titmouse (Baeolophus ridgwayi) bill morphology?

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