Okavango Nest Box Project

Region: The Okavango Delta, Botswana

The Okavango Nest Box Project (ONBP) aims to look at the ecology of Meyer’s Parrots in the Okavango Delta as a cavity nesting bird species in particular, as well as to research cavity nesting bird species in general – with an overall look at the availability and preference of nest cavities as a keystone for ecological processes of the species. The project includes all cavity nesting bird species using nest boxes. The data collected will be used to develop a strategy that will protect the species and the community in which it lives in the future.

Another aim of this project is to look at whether nest boxes can be successfully used to substitute the removal of old-growth timber and woodland habitat. This is especially important during these times when cavity nesters are threatened by increasing deforestation due to logging and burning. To this end, the project will assess both nest box preferences and breeding biology of bird species that make use of cavities in which to nest.

Other threats such as ectoparasites and predation will be investigated to determine how much of a limiting factor they are. The use of nest boxes and natural cavities by different species will be compared to see if a conservation plan for cavity nesting bird species can be developed.
The Okavango Nest Box Project is part of the larger Meyer’s Parrot Project and will last two years; it is hoped that the research will provide data for both projects.

• To determine which nest box design is preferred by which cavity nesting bird species and supports the highest fledging rates in the wild;
• Determine the seasonal nesting habitat preferences of the different cavity nesters using the nest boxes;
• Develop a breeding calendar for the different cavity nesters using the nest boxes;
• Record nest site attendance by adults during 12-hour nest observations;
• Record nest site temperature before, during and after incubation and fledging in the nest boxes;
• Sample ectoparasites in the nest boxes and natural cavities;
• Crop analysis of the nestlings to determine nutritional requirements in the wild;
• Record hatching sequence, egg size, and hatchling growth rate through daily inspection of active nest boxes;
• Determine the impact of predation on different species;
• Determine the impact of competition with bees on cavity nesting species; and
• Develop a conservation plan to accommodate all cavity nesting species represented in the fieldwork.

To achieve these objectives, several experiments will take place. Estimates of natural cavities will be obtained, and 30 wooden nest boxes, 105 PVC nest boxes and 45 palm trunk sections will be put up in dead or damaged Knobthorn or Leadwood trees in various ecotones and biomes, including riverine forest. Climate, temperature, humidity and other data will be recorded at each daily and nest boxes inspected.

During nesting season eggs will be measured, ectoparasites collected, behaviour observed and five breeding pairs will be radio-tagged to be tracked and monitored. Blood samples from adult birds will be collected for later analysis

The location of this study is Vundumtiki Island in the Kwedi Concession (NG22/23) in the Okavango Delta. The reason for this is that there is a large population of Meyer’s Parrot and other cavity nesting bird species in this area, with 25 active Meyer’s Parrot nest sites identified in the area, as well as the desired vegetation and habitat type. The Kwedi Concession has a total area of 960 square kilometres, and includes all wetland categories (perennial swamp, seasonal swamp, seasonally inundated grassland, intermittently inundated grassland and rainwater seepage pans) and all dry land categories (woodland, savannah, grassland, forbland).

Project update 2011
Research done over the last 4 years as part of the Okavango Nest Box Project in the Okavango Delta near Vumbura Plains has already started to benefit cavity-nesting bird communities in areas where forests have already been degraded. Our findings are being used by the World Parrot Trust Africa, Wild Bird Trust, and BirdLife South Africa to launch the largest nest box project ever undertaken on the African continent – the previous record holder was the Okavango Nest Box Project. They hope to erect over 300 nest boxes in degraded yellowwood forest patches along the Amathole mountain range in the Eastern Cape, South Africa.

Of the 105 nest boxes erected that were erected in early 2007, there are 98 remaining in use in the project. In addition to the nest boxes erected near Vumbura, we have over 85 sisal nest logs erected in Maun to compliment our primary research site in the wilderness. We have also partnered with Fabien Genin at the University of Fort Hare (Alice, South Africa) to monitor the utilization of artificial nest boxes by Lesser galagos (Galago moholi) and other mammals. We will be looking specifically at the use of trees that produce resin and competition between cavity-nesting birds, reptiles (e.g. tree monitor), mammals (e.g. galagos, tree squirrels, woodland dormice, etc.), and insects (e.g. beas, caterpillars, wasps, etc.). Preliminary assessment of our data suggests that we need to manipulate cavity entrance diameter to protect small cavity-nesting bird species from competition with larger mammals and birds. We have also noticed that the galagos dominate the nest boxes in areas with lots of resin-bearing trees and prefer to use Mopane (Colophospermum mopane) leaves as nesting materials due the high levels of tannins and extractives in these leaves, which apparently reduce the parasite load in long-term nest sites. Galagos were also found to establish small territories including up to six nest boxes. In 2011, we will move nest boxes that have not been used in two years, refurbish nest boxes damaged by baboons, elephants and harsh weather conditions, modify the hole aperture of the smaller nest boxes, and replace or remove nesting material where necessary. This will be a necessary preparation for the final five years of this 10-years study of application of nest boxes as a conservation tool.

Email contact: steve@wildbirdtrust.com

Update March 2010
In December 2009, the results of the 24-month survey of the artificial nest boxes were compiled. The project proved to be a success with an occupancy rate of over 75% of the nest boxes. Over 50% of all nest boxes were however occupied by tree squirrel, lesser bushbaby, and woodland dormouse, with several of these nests made over nesting material laid down by cavity-nesting birds. Both tree squirrel and woodland dormouse had young, while lesser bushbabies were found alone or in pairs, and utilised 3-4 nest boxes within a defined territory. On the other hand, nest boxes in riverine forest patches and acacia-combretum marginal woodlands were dominated by cavity-nesting bird species. African Grey Hornbills, Woodland Kingfishers, and Green Woodhoopoes were actively nesting during the survey, while several nest boxes had signs of historical occupation by Meyer’s Parrots and other secondary cavity-nesting bird species.

The findings demonstrate that given certain modifications to nest box design and location specifications, occupancy could be increased.

September 2009 Update
In January 2004, the Meyer’s Parrot Project was initiated by the Research Centre for African Parrot Conservation to facilitate learning and discovery about this previously unstudied, but topical and important transcontinental African parrot species in the wild. Three years later, in January 2007, the first independent research camp was established, thus allowing for the accommodation of volunteers so that every waking moment could be dedicated to parrot research.