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Authors: Lerma M, Dehnhard N,
Castillo-Guerrero JA, Hernandez-Vazquez S, Voigt CC, Garthe S
Abstract Animals that co-occur in a region (sympatry)
may share the same environment (syntopy), and niche differentiation is
expected among closely related species competing for resources. The
masked booby (Sula dactylatra) and smaller congeneric
red-footed booby (Sula sula) share breeding grounds. In
addition to the inter-specific size difference, females of both species
are also larger than the respective males (reversed sexual size
dimorphism). Although both boobies consume similar prey, sometimes in
mixed-species flocks, each species and sex may specialize in terms of
their diet or foraging habitats. We examined inter- and intra-specific
differences in isotopic values (δ13C and δ15N) in these pelagically
feeding booby species during the incubation period at Clarion Island,
Mexico, to quantify the degrees of inter- and intra-specific niche
partitioning throughout the annual cycle. During incubation, both
species preyed mainly on flyingfish and squid, but masked boobies had
heavier food loads than red-footed boobies. There was no overlap in
isotopic niches between masked and red-footed boobies during breeding
(determined from whole blood), but there was slight overlap during the
non-breeding period (determined from body feathers). Female masked
boobies had a higher trophic position than conspecific males during
breeding; however, no such pattern was detected in red-footed boobies.
These results provide evidence of inter- and intra-specific niche
partitioning in these tropical seabird species, particularly during the
breeding period and in the more-dimorphic species. Our results suggest
that these closely related species use different strategies to cope with
the same tropical marine environment.
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publication
Authors: Lerma M, Villavicencio CP,
Luna N, Portflitt-Toro M, Serratosa J, Luna-Jorquera G, Garthe S, Quispe
R
Abstract Understanding the physiology of stress in wild
animals is essential for the conservation of species subject to
anthropogenic perturbations. Humboldt penguins (Spheniscus
humboldti) are exposed to increasing anthropogenic impacts in their
natural habitat. In this species, females are typically smaller and dive
less deep than males. In related species, the more limited foraging
habitat of females and their reduced resiliency due to their smaller
size were associated with higher mortality. We hypothesise that
potential sex-specific differences in the foraging behaviour of Humboldt
penguins may also relate to differences in their physiological stress.
Here, we studied sex-specific foraging and diving behaviours and
variations in plasma corticosterone levels and leukocyte profiles of
Humboldt penguins during the chick-rearing period in Northern Chile. We
report no evidence of sex-related differences in most foraging
parameters, except that males dived significantly deeper than females.
We found that plasma corticosterone levels and leukocyte profiles showed
no significant differences between the sexes. Furthermore, there was no
clear relationship between an individual’s foraging behaviour and its
plasma corticosterone level or leukocyte profile. In summary, we found
no support for sex-related differences in physiological stress levels of
Humboldt penguins, and no link between their foraging behaviour and
their physiological stress. However, we acknowledge that our sample size
is small and that more studies are needed. This study contributes with
information on the physiological stress and foraging behaviours of
Humboldt penguins in Northern Chile. This information can help to
understand context-dependent differences in physiological parameters and
foraging behaviours for the species.
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to publication
Authors: Nourani E, Kamran S, de Grissac S, Anderson
D, Cole NC, Gremillet D, Lempidakis E, Lerma M, McKee
JL, Pichegru :, Provost P, Rattenbourg NC, Ryan P, Santos CD, Schoombie
S, Tatayah V, Weimerskirch H, Wikelski M, Shepard ELC
Abstract Storms can cause widespread seabird stranding
and wrecking, yet little is known about the maximum wind speeds that
birds are able to tolerate or the conditions they avoid. We analyzed
>300,000 h of tracking data from 18 seabird species, including
flapping and soaring fliers, to assess how flight morphology affects
wind selectivity, both at fine scales (hourly movement steps) and across
the breeding season. We found no general preference or avoidance of
particular wind speeds within foraging tracks. This suggests seabird
flight morphology is adapted to a “wind niche,” with higher wing loading
being selected in windier environments. In support of this, wing loading
was positively related to the median wind speeds on the breeding
grounds, as well as the maximum wind speeds in which birds flew. Yet
globally, the highest wind speeds occur in the tropics (in association
with tropical cyclones) where birds are morphologically adapted to low
median wind speeds. Tropical species must therefore show behavioral
responses to extreme winds, including long-range avoidance of wind
speeds that can be twice their operable maxima. By contrast,
Procellariiformes flew in almost all wind speeds they encountered at a
seasonal scale. Despite this, we describe a small number of cases where
albatrosses avoided strong winds at close range, including by flying
into the eye of the storm. Extreme winds appear to pose
context-dependent risks to seabirds, and more information is needed on
the factors that determine the hierarchy of risk, given the impact of
global change on storm intensity.
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to publication
Authors: Lerma M, Dehnhard N,
Castillo-Guerrero JA, Fernandez G
Abstract Individual body condition is frequently used
to explain differences in foraging and breeding ecology in seabirds.
However, little is known about the covariations of body mass with the
nutritional state of animals as measured through plasma metabolites and
how these different measures vary between and within individuals during
breeding. Here, we assessed intra-individual variations of plasma
metabolites (triglycerides, cholesterol, protein, and ß-hydroxybutyrate
concentrations) and in body mass of Blue-footed boobies (Sula
nebouxii) throughout their breeding season 2011–2012 in Isla El
Rancho, Mexico. We found breeding-stage and sex-specific variations in
individuals’ plasma metabolite concentrations, but these did not mirror
variations in body mass. Before egg-laying, females had higher
triglycerides, cholesterol, and protein concentrations than males. In
contrast, males used their nutritional reserves (higher
ß-hydroxybutyrate concentrations) more than females during the breeding
season (except for early chick-rearing). At the individual level, males
gained weight during the breeding season, whereas females lost weight.
We also found that between-individual differences in plasma metabolite
concentrations and changes in body mass were not consistent throughout
the breeding season, while individual body mass was significantly
repeatable. This study contributes to a better understanding of seabird
breeding ecology and physiology by showing that sex-specific breeding
roles might highly influence the nutritional state. Similar patterns
might occur in other seabird species, helping to explain why we can find
stage- and sex-specific foraging behaviors even in monomorphic
species.
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publication
Authors: Lerma M, Dehnhard N,
Luna-Jorquera G, Voigt CC, Garthe S
Abstract Sexual segregation in foraging occurs in some
species and populations of boobies (Sulidae), but it is not a general
pattern. Sexual segregation in foraging may occur to avoid competition
for food, and this competition may intensify during specific stages of
breeding. We examined sexual segregation in foraging in relation to
breeding stage in masked boobies Sula dactylatra at Rapa Nui by
tracking simultaneously incubating and chick-rearing birds using GPS
recorders (n = 18) and collected a total of 11 regurgitate samples.
Stable isotope analyses (δ13C and δ15N) of whole blood samples were
carried out in 20 birds. There were no differences in foraging trip
parameters or diet between females and males. Both sexes traveled
farther and for longer while incubating than while rearing chicks.
Isotopic niches (δ13C and δ15N) overlapped to some degree among all
groups at all times, but the lowest overlap between sexes occurred
during incubation. While preying on ephemerally distributed flying fish,
vertical or horizontal competition avoidance may be almost impossible,
and thus females and males share their foraging grounds. Since birds
were tracked simultaneously, shorter foraging trips of chick-rearing
birds must be an effect of the constraints of provisioning the chick.
Differences observed in δ15N and δ13C values between sexes may be caused
by subtle differences in their foraging behaviors, or by differences in
physiology linked to breeding. Our findings suggest that local
oceanography and its inherent food distribution are determinants for
sexual segregation in foraging patterns in masked boobies and possibly
also other booby species.
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publication
Authors: Quispe R, Lerma M, Luna N,
Portflitt-Toro M, Serratosa J, Luna-Jorquera
Abstract The largest population of Humboldt Penguins
resides in a fertile archipelago of the north-central coast of Chile,
formed by eight islands in proximity to upwelling centers of the
Humboldt Current System. However, five of these islands lack legal
protection. Here, we report the results of breeding Humboldt Penguins
tracked while foraging from Tilgo Island. The average and maximum
foraging radii around the colony were 22 km and 43 km, respectively. Our
data indicate that trip ranges overlap areas proposed for industrial
projects. Because Humboldt Penguins are sentinels of local ecosystem
health, this underscores the value of expanding conservation zones in
this unique marine location.
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publication
Authors: Lerma M, Castillo-Guerrero
JA Hernandez-Vazquez S, Garthe S
Abstract The El Niño Southern Oscillation (ENSO) is a
recurrent climatic pattern with important ecological consequences for
seabirds due to its impacts on the abundance and distribution of food
resources. We investigated the effects of ENSO phases on the foraging
ecology of a marine top predator at Clarion Island in the Eastern
Tropical Pacific using GPS and time-depth recorder data and regurgitates
from incubating masked boobies (Sula dactylatra) during 3
consecutive years. Foraging locations were recorded in 2016 (El Niño,
one female, three males), 2017 (neutral; six females, nine males), and
2018 (La Niña; eight females, ten males). Local sea surface temperature
(SST) and chlorophyll-a concentration (CHL) within the birds’ foraging
range were compared among the 3 years. Regurgitates were collected
opportunistically from 25 and 31 incubating adults in 2017 and 2018,
respectively. Average local CHL and SST were similar among years (mean
SST 25 °C; mean CHL 0.10 and of 0.09 mg m−3 in January and March,
respectively). Masked boobies travelled a maximum of 66 ± 34 km from the
colony. The maximum trip duration was 7.7 ± 3.4 h and total distance
travelled during a foraging trip was 164 ± 73 km, with no sex- or
year-related differences. Masked boobies mainly caught flying fish, but
their diet also included one squid and six other fish families. In
contrast to previously reported changes in foraging ecology of seabirds,
masked boobies at Clarion Island seemed to be unaffected during El Niño,
because the local oceanography was relatively unperturbed by ENSO
oscillations.
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publication
Authors: Lerma M, Serratosa J,
Luna-Jorquera G, Garthe S
Abstract The South Pacific Gyre has the most
hyper-oligotrophic waters in the world and is considered the largest
“oceanic desert.” Rapa Nui (Easter Island), located within the South
Pacific Gyre, is a breeding ground for masked boobies (Sula
dactylatra), which are seabirds with a foraging range that
effectively confines them within the gyre. The foraging ecology of this
species in the gyre was examined by attaching GPS and time-depth devices
to chick-rearing adult birds (9 and 14 birds in 2016 and 2017,
respectively) and by collecting regurgitates (18 and 15 samples in 2016
and 2017, respectively). In addition, the birds’ foraging ecology
between years was compared. Masked boobies traveled in various
directions, dived at unspecific locations, and explored areas < 110
km from the colony. Local environmental conditions were not
significantly different between years, and differences in foraging
parameters (maximum foraging range, trip duration, and dive depth) were
greater among individuals than between years. The foraging
characteristics of masked boobies suggest that resources were
ephemerally distributed around the colony, with similar abundances
across years. Under these conditions, traveling to unspecific locations
may increase the area covered and the probability of prey encounter. The
spatial and temporal consistencies in environmental conditions explain
the uniformity of foraging parameters between years. The ability of
masked boobies to exploit ephemerally distributed resources in seascapes
like Rapa Nui may help explain its pantropical distribution.
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publication
Authors: Lerma M, Castillo-Guerrero
JA, Garcia-Hernandez J, Fernandez G
Abstract Zinc is essential for animal metabolism, but
the variation in Zn concentrations within seabird populations has been
seldom explored. We collected Blue-footed booby (Sula nebouxii)
eggs during 2012 and 2013 and blood samples from nestlings and adults
during 2011 and 2012 in Sinaloa, Mexico, to evaluate differences in Zn
concentrations among years, ages, sexes, and breeding stages. Zinc
concentrations in eggs ranged between 27.3 and 64.9 ppm (dry weight),
whereas Zn levels in the blood of nestlings and adults ranged between
16.1 and 53.1 ppm (dry weight). Egg Zn concentrations did not differ due
to developmental stage, although Zn concentrations were significantly
higher in 2013 than in 2012. Nestling Zn concentrations differed between
years and decreased gradually with age. Chicks had significantly higher
Zn concentrations than those of adults. Once nestlings stopped growing,
females presented higher Zn concentrations than males. Adult Zn
concentrations were higher during the pre-laying period than during the
other breeding stages. Our results suggest that growth, sex, and
breeding stage affect blood Zn concentrations, which may be due to
stage-specific requirements. When compared with those of other seabird
species, the Zn concentrations reported here are intermediate, and we
did not detect adverse effects on either nestlings or adults.
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publication
Authors: Lerma M, Castillo-Guerrero
JA, Palacios E
Abstract The American Oystercatcher (Haematopus
palliatus frazari) is federally listed as endangered in Mexico due
to habitat loss and small population size. Recent surveys indicate that
the State of Sinaloa supports about half of the breeding population in
Mexico. However, no information is available about the non-breeding
ecology in Mexico. To assess American Oystercatcher distribution,
abundance, and roosting habitat use during the nonbreeding season (3
August 2014-23 January 2015), six bays were surveyed in Sinaloa. A total
of 1,351 American Oystercatchers were detected using this area based on
maximum count per roosting site at or near high tide. American
Oystercatchers roosted in flocks of variable size (3–253 individuals per
flock) with Bahía Santa María hosting the main roosting sites in
Sinaloa. Mangrove islands and mudflats had larger numbers of individuals
than expected relative to the availability of those habitats. The
non-breeding Sinaloa population comprised approximately 45.0% of the
total H. p. frazari population estimate (n = 3,000 individuals). Bahía
Santa María represented 74.6% of the non-breeding population observed in
Sinaloa. Thus, Sinaloa, and particularly Bahía Santa María, stand out as
critical sites for the conservation of this subspecies. Hypothesized
threats to American Oystercatchers were predators, livestock, and human
activities.
Read more: Full Publication
Authors: Lerma M, Castillo-Guerrero
JA, Ruelas-Inzunza J, Fernandez, G
Abstract We used blood samples of the Blue-footed
Booby, considering sex (female and male) and age-class (adult and chick)
of individuals at different breeding stages during two breeding seasons
(2010–2011 and 2011–2012) in Isla El Rancho, Sinaloa, to determine lead,
cadmium, and mercury concentrations. Lead and cadmium concentrations
were below our detection limit (0.05 and 0.36 ppm, respectively). A
higher concentration of mercury was found in early stages of breeding,
likely related to changes in mercury environmental availability. Mercury
concentrations in adults did not relate with their breeding output.
Males and adults had higher mercury concentration than females and
chicks. We provide information of temporal, sex and age-related
variations in the concentrations of mercury in blood of the Blue-footed
Booby.
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Publication
Authors: Castillo-Guerrero JA, Lerma
M, Mellink E, Suazo-Guillén E, Peñaloza-Padilla EA
Abstract The Brown Booby Sula leucogaster is a
seabird with a pantropical distribution across a wide variety of oceanic
environments. Sexual size dimorphism in Brown Boobies has been proposed
as an explanation for intersexual differences in foraging, but results
have been inconsistent. We investigated whether there is
context-dependent foraging behaviour driven by local environmental
conditions. In this study, we evaluated (1) inter-sex differences in
foraging behaviour (by capillary tubes, temperature and depth recorders,
and diet) at two colonies in the Gulf of California: Isla San Jorge
(ISJ) and Farallón de San Ignacio (FSI) and, (2) intercolonial and
interannual differences in foraging behaviour, and (at ISJ) their
relationship with local-scale environmental variation, using 5-day
composite images of sea surface temperature (SST) and primary
productivity (PP) as proxies. Inter-sex differences were few and
inconsistent between years, and smaller than overall differences between
years and localities. At ISJ, Brown Boobies included more prey species
in their diet (27 vs. 19 spp.) and dove shallower (2.3 vs. 3.14 m) than
at FSI. At ISJ, Brown Boobies exhibited adjustments in diving depth and
prey size as a function of environmental variation: shallower plunge
dives and smaller prey items were related with lower SST and higher PP
values, whereas deeper dives and larger prey items were related with
higher SST and lower PP values. Our results confirmed that the Brown
Booby is highly plastic in its foraging ecology, which explains its
ability to live in places with large-scale environmental variation
(intercolony and interannual), such as tropical areas worldwide.
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