Timing and location of reproduction in African waterfowl: an overview of &gt;100 years of nest records

The community dynamics of organisms that exhibit multi‐scale responses to habitat change are poorly understood. We quantified changes in species diversity and the functional composition of a waterbird community over two iterations of a repeated transition, the annual drying‐down of arid‐region Lake Ngami, Botswana. We used our data to test three theoretical predictions: simplification of the bird community over time due to a reduction in habitat area and concurrent niche loss; large fluctuations in densities of mobile, opportunistic species; and high variance in predator and prey abundance. Despite temporal variance in species accumulation, we observed no obvious simplification and distinct but consistent groupings of abundance and composition across transitional stages. There were some rapid shifts in functional composition, such as loss of deepwater foragers; winners and losers also occurred within foraging guilds. We conclude that understanding community‐level trends during transitional periods will require stronger theoretical frameworks that more effectively integrate unique species traits and functional groups. For conservation managers, our study offers a cautionary tale of the importance of understanding connectivity, trajectories of change, and the potential for large fluctuations in animal communities independent of management actions during periods of ecological transition.

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“…Predation on juvenile waterfowl is considered an important influence on their breeding patterns across southern Africa (Cumming et al. 2016).…”

Section: Discussionmentioning

confidence: 99%

Understanding arid‐region waterbird community dynamics during lake dry‐downs

et al. 2021

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“…, Cumming et al . ). In addition, the seasonal aggregation of waterfowl in Afrotropical regions can be related to the gathering of birds at permanent wetlands at the end of the dry season in response to the drying of wetlands (Cappelle et al .…”

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confidence: 97%

The role of breeding phenology and aggregation of waterfowl on avian influenza dynamics in southern Africa

Mundava

Caron

Garine‐Wichatitsky

et al. 2016

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Recent outbreaks of highly pathogenic avian influenza virus (AIV) in birds, humans and other mammalian species calls for a better understanding of virus dynamics in wild bird species and populations that act as maintenance hosts. Host ecology influences the transmission of pathogens and can be used to explore and infer pathogen dynamics. Most of the ecological processes proposed to explain AIV transmission in wild birds have been derived from studies conducted in the temperate and boreal regions of the northern hemisphere. We evaluate the role of two key drivers of AIV dynamics in a waterfowl community in Zimbabwe (southern Africa): (1) the recruitment of young birds and (2) the seasonal aggregation of birds. We analyse the seasonal variation of AIV prevalence in waterfowl and overlay these data with the phenology of reproduction and the seasonal variation in the local abundance of these species. We find that the breeding period of southern Afrotropical waterfowl species is more extended and somewhat less synchronized among species in the community than is the case in temperate and boreal waterfowl communities. Young birds are recorded at most times of the year, and these immunologically naïve individuals can therefore act as new hosts for AIV throughout the year within the wild bird population. Although host aggregation peaks in the cold-dry to hot-dry season, birds still aggregate throughout the year and this potentially spreads the opportunities for first infection of juveniles and other naïve birds temporally. We did not find a relationship between season, AIV prevalence in waterfowl, the influx of juveniles or the gradual aggregation of birds during the dry season. Therefore, the main drivers of AIV dynamics (juvenile influx and host abundance/aggregation), although present in Afrotropical regions, could not explain the AIV seasonal patterns in our study in contrast to results reported from temperate and boreal regions. These differences imply variation in the risk of AIV circulation in waterfowl and in the risk of spread to poultry, other animals or humans. (Résumé d'auteur

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“…Unlike Mallards in Africa and North America that nest in the middle of Austral‐summer (January; Cumming et al . ) or Austral‐autumn (April–May; Drilling et al . , Fouzari et al .…”

Section: Discussionmentioning

confidence: 99%

“…Ubiquitous throughout their Holarctic range, introduced Mallard populations have also become naturalized in parts of mainland Africa, Australia, South America, and on oceanic islands throughout the world, including Mauritius, the Falkland Islands, Hawaii and NZ (Baldassarre , Cumming et al . ). Mallards are highly adaptable habitat generalists; in their native range they consume a wide variety of foods including crop residues, tolerate urban environments, use all types of freshwater and brackish habitats, and nest in numerous habitat types (Bellrose & Kortright , Baldassarre ).…”

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Nesting ecology of a naturalized population of MallardsAnas platyrhynchosin New Zealand

Sheppard

Amundson

Arnold

et al. 2018

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Investigating the reproductive ecology of naturalized species provides insights into the role of the source population's characteristics vs. post-release adaptation that influence the success of introduction programmes. Introduced and naturalized Mallards Anas platyrhynchos are widely established in New Zealand (NZ), but little is known regarding their reproductive ecology. We evaluated the nesting ecology of female Mallards at two study sites in NZ (Southland and Waikato) in 2014-15. We radiotagged 241 pre-breeding females with abdominal-implant transmitters and measured breeding incidence, nesting chronology and re-nesting propensity. We monitored 271 nests to evaluate nest survival, clutch and egg size, egg hatchability and partial clutch depredation. Breeding incidence averaged (mean AE se) 0.91 AE 0.03, clutch size averaged 9.9 AE 0.1 eggs, 94 AE 2% of eggs hatched in successful nests, partial depredation affected 6 AE 1% of eggs in clutches that were not fully destroyed by predators, and re-nesting propensity following failure of nests or broods was 0.50 AE 0.003. Nesting season (first nest initiated to last nest hatched) lasted 4.5 months and mean initiation date of first detected nest attempts was 28 August AE 3.3 days. Smaller females were less likely to nest, but older, larger or better condition females nested earlier, re-nested more often and laid larger clutches than did younger, smaller or poorer condition females. Younger females in Southland had higher nest survival; cumulative nest survival ranged from 0.25 AE 0.007 for adult females in Waikato to 0.50 AE 0.007 for yearling females in Southland. Compared with Mallards in their native range, the nesting season in NZ was longer, clutches and eggs were larger, and nest survival was generally greater. Different predators and climate, introgression with native heterospecifics and/or the sedentary nature of Mallards in NZ may have contributed to these differences.

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Timing and location of reproduction in African waterfowl: an overview of >100 years of nest records

Cited by 9 publications

References 43 publications

Understanding arid‐region waterbird community dynamics during lake dry‐downs

Understanding arid‐region waterbird community dynamics during lake dry‐downs

The role of breeding phenology and aggregation of waterfowl on avian influenza dynamics in southern Africa

Nesting ecology of a naturalized population of MallardsAnas platyrhynchosin New Zealand

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