Vocalisations represent the primary mode of communication for most birds and vary greatly in form and function within and between species. Cataloguing the vocal repertoire of a species is a key ...foundation for behavioural research, as it provides both an objective measure of vocal complexity and a basis for further studies of vocal function. Here we present a descriptive catalogue of the vocal repertoire of the Chestnut-crowned Babbler (Pomatostomus ruficeps), a cooperatively breeding passerine endemic to inland south-eastern Australia. Using behavioural observations and simple methods of acoustic classification we identify and suggest functions for 13 main types of vocalisations, and also report five less common vocalisations that could not be assigned a unique function. Babblers possess no song, in the sense of a vocalisation primarily used for inter-group or territorial communication. The 13 calls with clear functions can be broadly classified into three alarm calls, five contact calls, and four social-interaction calls, with a final call used in both social and alarm contexts. This study represents the first catalogue of vocal repertoire in pomatostomid babblers, and aims to contribute to future comparative analyses of vocal complexity and inspire further work on the relationship between call structure and function.
In many species, individuals must contribute extensively to offspring care to reproduce successfully. Within species, variation in care is driven by local social, physiological, and environmental ...contexts, and this relationship has been a major focus of behavioral ecology since the inception of the field. The majority of existing studies on care, both theoretical and empirical, have focused on measuring the amount of care delivered by each carer as a proxy for individual investment, linking this investment to the local context, and investigating outcomes for offspring. However, more recently interest has grown in the finer-scale details of care, including how individuals respond to each other's behavior, and temporal variation in care both within and between stages. Simultaneously, advances in remote monitoring methods, such as video cameras and passive integrated transponder (PIT) tag systems, have vastly increased the ease of collecting large amounts of care data, providing opportunities to study carer behavior in much greater detail than previously possible. In this mini-review we provide an overview of the dimensions of carer behavior that can be quantified, illustrated using recent studies from a variety of taxa. We classify these analyses into three broad groups: (a) how parental care is distributed in time, (b) variation within care events, and (c) how carers interact when jointly providing care. Our aim is to encourage more in-depth analyses of parental care, to build a more complete picture of how animals rear their offspring.
Southern Asia experiences some of the most damaging climate events in the world, with loss of life from some cyclones in the hundreds of thousands. Despite this, research on climate extremes in the ...region is substantially lacking compared to other parts of the world. To understand the narrative of how an extreme event in the region may change in the future, we consider Super Cyclone Amphan, which made landfall in May 2020, bringing storm surges of 2–4 m to coastlines of India and Bangladesh. Using the latest CMIP6 climate model projections, coupled with storm surge, hydrological, and socio‐economic models, we consider how the population exposure to a storm surge of Amphan's scale changes in the future. We vary future sea level rise and population changes consistent with projections out to 2100, but keep other factors constant. Both India and Bangladesh will be negatively impacted, with India showing >200% increased exposure to extreme storm surge flooding (>3 m) under a high emissions scenario and Bangladesh showing an increase in exposure of >80% for low‐level flooding (>0.1 m). It is only when we follow a low‐emission scenario, consistent with the 2°C Paris Agreement Goal, that we see no real change in Bangladesh's storm surge exposure, mainly due to the population and climate signals cancelling each other out. For India, even with this low‐emission scenario, increases in flood exposure are still substantial (>50%). While here we attribute only the storm surge flooding component of the event to climate change, we highlight that tropical cyclones are multifaceted, and damages are often an integration of physical and social components. We recommend that future climate risk assessments explicitly account for potential compounding factors.
Tropical cyclones in South Asia can be devistating, with the 2020 Super Cyclone Amphan being the costliest on record for India and Banglesdesh. We consider how the population exposed to a tropical cyclone storm surge, and subsequnet flooding, will change in the future given varying degrees of sea level rise. We show significant increases in exposure for both countries, but when future population movement is taken into account, the increased flood impacts are smaller in Bangledesh due to migration of people away from the coast.
We investigated the effect of leaf age on the response of net photosynthesis (A), stomatal conductance (
g
wv
), foliar injury, and leaf nitrogen concentration (N
L) to tropospheric ozone (O
3) on
...Prunus serotina seedlings grown in open-plots (AA) and open-top chambers, supplied with either carbon-filtered or non-filtered air. We found significant variation in A, g
wv
, foliar injury, and N
L (
P < 0.05) among O
3 treatments. Seedlings in AA showed the highest A and g
wv
due to relatively low vapor pressure deficit (VPD). Older leaves showed significantly lower A, g
wv
, N
L, and higher foliar injury (
P < 0.001) than younger leaves. Leaf age affected the response of A, g
wv
, and foliar injury to O
3. Both VPD and N
L had a strong influence on leaf gas exchange. Foliar O
3-induced injury appeared when cumulative O
3 uptake reached 8–12 mmol m
−2, depending on soil water availability. The mechanistic assessment of O
3-induced injury is a valuable approach for a biologically relevant O
3 risk assessment for forest trees.
Ozone effects on symptom development and leaf gas exchange interacted with leaf age and N-content on black cherry seedlings.
This paper describes the development and flight test of autonomous obstacle field navigation and safe landing area selection on the U.S. Army Aeroflightdynamics Directorate RASCAL JUH‐60A research ...helicopter. Using laser detection and ranging (LADAR) as the primary terrain sensor, the autonomous flight system is able to avoid obstacles, including wires, and select safe landing sites. An autonomous integrated landing zone approach profile was developed and validated that integrates cruise flight, low‐level terrain flight, and approach to a safe landing spot determined on the fly. Results are presented for a range of sites and conditions. Approximately 750 km of autonomous flight was performed, 230 km of which was at low altitude in mountainous terrain using the obstacle field navigation system. This is the first time a full‐scale helicopter has been flown fully autonomously a significant distance in low‐level flight over complex terrain, basing its planning solely on sensor data gathered from an onboard sensor. These flights demonstrate tight integration between terrain avoidance, control, and autonomous landing.
Many young birds die soon after fledging, as they lack the skills to find food and avoid predation. Post-fledging parental care is assumed to assist acquisition of these vital skills. However, we ...still lack empirical examples examining the length of time fledglings spend with parents, how they associate during this critical time, or whether such variation in the fledgling dependency period has consequences for the survival and behaviour of young as they navigate their first year of independent life. Here, we make use of observations and radio frequency identity (RFID) logs of visits to supplementary feeding stations to investigate how condition of fledgling hihi (stitchbird, Notiomystis cincta), a New Zealand passerine, predicts dispersal behaviour and tendency to follow parents during their 2 week post-fledging dependence period. We find that thinner fledglings followed their parents more closely in time when visiting feeding stations, compared to fatter siblings (all following ranged from 3 s to 10 min). However, broods in poorer condition tended to disperse from the natal territory up to 6.5 days earlier than broods of fatter fledglings (all dispersed within 14 days). Our results did not find that sociality or survival during the first year of life differed depending on variation in fledgling behaviour; neither following parents closely nor dispersing later predicted each bird's number of associates (degree), or survival over winter. These results suggest that fledglings may be able to compensate for early differences in condition with behaviour, either during the post-fledging dependence period or when independent.
Flood inundation modeling across large data sparse areas has been increasing in recent years, driven by a desire to provide hazard information for a wider range of locations. The sophistication of ...these models has steadily advanced over the past decade due to improvements in remote sensing and modeling capability. There are now several global flood models (GFMs) that seek to simulate water surface dynamics across all rivers and floodplains regardless of data scarcity. However, flood models in data sparse areas lack river bathymetry because this cannot be observed remotely, meaning that a variety of methods for approximating river bathymetry have been developed from uniform flow or downstream hydraulic geometry theory. We argue that bathymetry estimation in these models should follow gradually varying flow theory to account for both uniform and nonuniform flows. We demonstrate that existing methods for bathymetry estimation in GFMs are only accurate for kinematic water surface profiles and are unable to simulate unbiased water surface profiles for reaches with diffusive or shallow water wave properties. The use of gradually varied flow theory to estimate bathymetry in a GFM reduced model error compared to a target water surface profile by 66% and eliminated bias due to backwater effects. For a large‐scale test case in Mozambique this reduced flood extents by 40% and floodplain storage by 79% at the 5 years return period. The wet bias associated with uniform flow derived channels could have significant implications for modeling the role floodplains play in attenuating river discharges, potentially overstating their role.
Key Points
Flood models in data sparse areas must estimate river bathymetry
Existing methods are prone to over‐prediction bias
Channel estimation based on gradually varied flow theory is substantially more accurate
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