Assessing the extinction risk of the great bustard Otis tarda in Africa

Palacín, C., Martín, B., Onrubia, A. & Alonso, J. C. 2016. Assessing the extinction risk of the great bustard Otis tarda in Africa. Endang Species Res 30: 73–82. doi: 10.3354/esr00726 (Open Access)

Abstract:

We studied the dynamics and trend of the last extant population of great bustards Otis tarda in Africa. Moroccan great bustards are the southernmost population of this species, and thus show the characteristics of a peripheral population: small size, isolation and low gene flow. Available counts indicate a severe population decline (62% in the last 15 yr), as well as a contraction of the species’ distribution. We used a population viability analysis (PVA) to evaluate the quasi-extinction risk and to identify the most important threats. The estimated geometric growth rate of the more realistic of a set of possible scenarios was 0.87 (95% CI: 0.85, 0.89). This implies a 13% annual decline over 50 yr. However, projections derived from these results should be interpreted with caution, because models have a great deal of uncertainty and vital rates from Iberian populations may be different from those of the Moroccan population. PVA showed the negative consequence of human-induced mortality. According to the model that best fits our census data and if present threats remain in the coming years, this peripheral population could go extinct in ca. 20 yr. Agricultural intensification, infrastructure developments and new power lines in rural areas where the species occurs are causing habitat destruction and fragmentation and increasing artificial mortality. Urgent conservation measures, especially to reduce human-induced mortality, are needed to save African great bustards from extinction. We suggest that these findings can be generalized to other peripheral great bustard populations living in highly humanized landscapes.

Great Bustard (Otis tarda): a vulnerable species
Great Bustard (Otis tarda): a vulnerable species (Andrej Chudý, via Wikipedia Commons)

Breeding ecology of Turtle Doves (Streptopelia turtur) on intensively cultivated farmland

Hanane, S. (2016). Effects of location, orchard type, laying period and nest position on the reproductive performance of Turtle Doves (Streptopelia turtur) on intensively cultivated farmland. Avian Research 7: 4.  doi: 10.1186/s40657-016-0039-0 (Open Access)

Abstract

Background
Until recently little was known about factors affecting reproductive parameters of the Turtle Dove (Streptopelia turtur) on intensively cultivated farmland in the Mediterranean area. In this study, the reproductive parameters of this game species were evaluated in relation to location, orchard type, laying period and nest position in central Morocco.

Methods
A total of 317 nests were found and analyzed across five breeding seasons (2004–2008) in the Haouz and Tadla regions, over two major agro-ecosystems made up of olive and orange orchards. Nest position, laying period, clutch size and the number of chicks hatched and fledged per nest were determined on 120 study plots. I used Generalized Linear Models (GLMs) with a Poisson distribution and a log link function, including the logarithm of the number of eggs in each clutch as an offset to model the number of chicks hatched and fledged per nest.

Results
Clutch-size was not affected by location, orchard type, laying period or nest position. The number of chicks hatched per nest differed between orchard types; they were greater in olive orchards (1.33 ± 0.06) than in orange ones (1.03 ± 0.08), whereas the number of chicks fledged per nest consistently differed with laying period and orchard type, which were higher in the early laying period (1.22 ± 0.07) than in the late period (0.93 ± 0.08) and higher in olive orchards (1.22 ± 0.06) than in orange orchards (0.90 ± 0.06). Neither location nor nest position were related to variation in the fledging success of the Turtle Dove.

Conclusions
Olive orchards and the early laying period confer better nesting conditions than orange orchards and the late laying period. Although nest position could be different in each orchard type, it did not affect the breeding success of the Turtle Dove, suggesting that factors other than tree characteristics are influential. Further studies are needed to improve our understanding of the effects of anthropogenic disturbance, especially agricultural activities and hunting, on the productivity of Turtle Dove nests.

 

Turtle Doves: nest with two eggs, newly hatched chick, and adult at nest with its chicks

a) A nest of a Turtle Dove with two eggs on an olive tree. b) A nest of Turtle Dove with a newly hatched chick on an orange tree. c) A Turtle Dove at nest with its chicks on an orange tree (Saâd Hanane)

 

 

Breeding biology of sympatric Laughing (Streptopelia senegalensis) and Turtle (Streptopelia turtur) Doves in NE Algeria

Brahmia, H., Zeraoula, A., Bensouilah, T., Bouslama, Z., & Houhamdi, M. 2015. Breeding biology of sympatric Laughing Streptopelia senegalensis and Turtle Streptopelia turtur Dove: a comparative study in northeast Algeria. Zoology and Ecology  25(3): 220–226.   doi: 10.1080/21658005.2015.1049470
PDF in ResearchGate.net

Abstract:

The Turtle Dove and Laughing Dove display distinct behavior and are morphologically and genetically different. However, microhabitat selection and reproductive success details of the two species are still poorly studied. The geographic distribution of the Laughing Dove in North Africa has clearly expanded nowadays. The breeding ecology and nest placement of this species have been studied previously, but little is currently known about its life history in Algeria. This study aimed to provide the basic information on the breeding biology of the Laughing Dove in Algeria. During two consecutive breeding seasons (2013–2014), the clutch size, brood size, chick survival, timing of breeding, densities of breeding pairs, nest placement, and the main causes of nest failure of the sympatric Laughing Dove and Turtle Dove were studied in an olive orchard in Guelma region, northeast Algeria. Clutch size, brood size, chick survival, the estimated productivity, and nest placement of the two species were similar but timing of breeding and population densities were significantly different. Finally, the largely coincident egg-laying period and the similar clutch size of the two species seem to be the main factors behind their similar survival rate and productivity in our study area.

Laughing Dove (Streptopelia senegalensis), Helwan, Egypt

Laughing Dove (Streptopelia senegalensis), Helwan, Egypt (Rachid H., flickr)