General enquiries on this form should be made to: Defra, Procurements and Contracts Division (Science R&D Team) Telephone No. 0207 238 5734 E-mail: [email protected] SID 5 Research Project Final Report Note In line with the Freedom of Information Act 2000, Defra aims to place the results Project identification of its completed research projects in the public domain wherever possible. The 1. Defra Project code WC0732 SID 5 (Research Project Final Report) is designed to capture the information on 2. Project title the results and outputs of Defra-funded research in a format that is easily Impact of ring-necked parakeets on native birds publishable through the Defra website. A SID 5 must be completed for all projects. • This form is in Word format and the boxes may be expanded or reduced, as 3. Contractor appropriate. The Food and Environment Research organisation(s) Agency (Fera) ACCESS TO INFORMATION Sand Hutton The information collected on this form will York be stored electronically and may be sent YO41 1LZ to any part of Defra, or to individual researchers or organisations outside British Trust for Ornithology Defra for the purposes of reviewing the The Nunnery project. Defra may also disclose the Thetford information to any outside organisation Norfolk acting as an agent authorised by Defra to IP24 2PU process final research reports on its behalf. Defra intends to publish this form on its website, unless there are strong 54. Total Defra project costs £ 147,148 reasons not to, which fully comply with (agreed fixed price) exemptions under the Environmental Information Regulations or the Freedom 5. Project: start date ................ 16/02/2009 of Information Act 2000. Defra may be required to release information, including personal data and end date ................. 30/11/2010 commercial information, on request under the Environmental Information Regulations or the Freedom of Information Act 2000. However, Defra will not permit any unwarranted breach of confidentiality or act in contravention of its obligations under the Data Protection Act 1998. Defra or its appointed agents may use the name, address or other details on your form to contact you in connection with occasional customer research aimed at improving the processes through which Defra works with its contractors. SID 5 (Rev. 07/10) Page 1 of 37 6. It is Defra’s intention to publish this form. Please confirm your agreement to do so. ...................................................................................... YES √ NO (a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. 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(b) If you have answered NO, please explain why the Final report should not be released into public domain Executive Summary 7. The executive summary must not exceed 2 sides in total of A4 and should be understandable to the intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work. SID 5 (Rev. 07/10) Page 2 of 37 Introduction The ring-necked or rose-ringed parakeet Psittacula kramerii is native to India and sub-Saharan Africa. It is the most widely introduced parrot species in the world and has successfully established breeding populations in 35 countries across five continents. In the UK, the main populations are currently concentrated in SE England and largely restricted to urban and semi-urban sites. The population, however, is undergoing a period of rapid growth that is likely to continue into the foreseeable future – abundance increased by over 600% between 1995 and 2007. The ring-necked parakeet is a secondary cavity nester, occupying cavities that are either natural or have been excavated by other species (primary cavity nesters). There is evidence that the parakeet competes with other cavity nesters, both in its native and introduced range - in Belgium, there is some evidence for such competition with nuthatches Sitta europaea . In the UK, parakeets initiate nesting much earlier than native species and have relatively long incubation and nestling periods; cavities, therefore, may already be occupied when native species initiate their own breeding cycle. Aims The overall aim was to investigate the potential impact of ring-necked parakeets on native birds. The resource for which competition is likely to be most intense is nest sites and the study, therefore, focussed on the potential impact of ring-necked parakeets on native cavity-nesting species. The study incorporated three elements: (i) analysis of existing BTO datasets concerning avian abundance, (ii) fieldwork investigating abundance of parakeets and native cavity nesters in relation to habitat characteristics, nest site selection and breeding success, and (iii) spatial modelling of potential parakeet range expansion. Species abundance Analysis of existing data from BTO/JNCC/RSPB Breeding Bird Survey (BBS), BTO Garden Birdwatch, BTO London Bird Project and BTO/RSPB/BWI/SOC BirdTrack found no significant relationship between numbers of parakeets and those of eight native cavity nesting species: blue tit, great tit, green woodpecker, great-spotted woodpecker, jackdaw, nuthatch, starling and stock dove. Further analysis of BBS data also showed no evidence that the population growth rate of any of the native species was related to parakeet numbers. While no significant negative impact of parakeets on native species was identified at the national scale, this analysis could not exclude the possibility that parakeets may have had a localised impact at a subset of sites where the intensity of competition was greatest. Between mid-February and mid-April 2010, therefore, three survey visits were conducted at each of 20 study sites located in London parkland to record numbers of parakeets and native species. The proportional cover of seven habitat classes (low, medium and high density woodland, improved grassland, scrub, open water and human habitation) was also recorded, along with the number of veteran trees (>5m circumference) at each site to obtain a measure of nesting cavity availability. Analyses of these data indicated no overall negative relationships between parakeet numbers and numbers of native species, even when the potential availability of cavities had been accounted for. Analysis of the interactions between parakeet abundance and habitat, however, showed that a decrease in the numbers of green woodpecker and stock dove with increased numbers of parakeet was apparent with decreasing proportion of continuous closed canopy woodland. This result suggests that some degree of competition may exist between parakeets and these two species at sites where cavities are limited. Nest habitat Throughout the 2010 breeding season (February to July), intensive searches of 15 of the 20 study sites were conducted regularly to locate the nest sites of all target species, of which five (ring-necked parakeet, nuthatch, starling, great-spotted woodpecker and jackdaw) were found in sufficient number to permit analysis. At each nest site, habitat characteristics were measured at three spatial levels: (i) the nest cavity, (ii) the nest tree, and (iii) the habitat immediately surrounding the tree. There was much similarity in nest habitat characteristics of some target species, with nuthatch and starling showing the greatest overlap with parakeets. However, when comparing the nest site habitat features of individual native species between sites with zero/low parakeet abundance and sites with high parakeet abundance there was an almost complete absence of any significant differences. This is consistent with a lack of evidence for the displacement of native species into less preferred cavities. Breeding parameters For all nest cavities that were accessible, data on laying dates and numbers of fledglings produced was collected during multiple visits using a pole-mounted miniature video camera. Considering all study sites, ring-necked parakeets initiated egg-laying significantly earlier (18-45 days per species) than native cavity- nesters - median first egg date = 24 th March. Parakeet productivity was estimated to be 2.2 ± 0.23 (n=39) SID 5 (Rev. 07/10) Page 3 of 37 fledglings per breeding pair and 2.6 ± 0.20 (n=33) fledglings per successful pair. Mean fledgling production was higher than recorded in previous studies. Nest failure, due to nest abandonment, predation or chick death was 11.3% (7/62 nests) across all sites. Starling laying dates were significantly later in sites with high abundance of parakeets compared to sites with zero/low abundance, but there was no significant difference in the number of young fledged between study sites with zero/low parakeet abundance and sites with high parakeet abundance for any of the four native species (nuthatch, starling, great-spotted woodpecker and jackdaw). Current impacts This fieldwork demonstrates the potential for nest site competition in the UK as parakeets favour similar types of cavity to some native species but occupy them significantly earlier. Despite this finding, there was no evidence of a negative impact of parakeets on species abundance or population growth rate at a national scale for any native species.