Five-minute grid of marine bird density data off central California, 1980-2001 (CDAS data set five-min-grid)

A shapefile of five minute grids with summary information on at-sea bird surveys from 1980-2001. Bird densities by ocean season, by species.

This shapefile was used to map density and other community metric maps for NOAA. It has a summary of marine bird survey data at sea, from 1980-2001, from the CDAS central CA data set.

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This file was developed by R.G. Ford Consulting Co. and includes eight survey data sets.

These data were prepared for an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data have been used by NOAA, no warranty, expressed or implied, is made by NOAA as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by NOAA in the use of these data or related materials.

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Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.0.1324

The at-sea density data, from which this shapefile was created, are the result of a synthesis of data from eight shipboard and aerial survey programs conducted in the study area in the years 1980-2001. Observation and trackline data from these studies were converted to a common format. All aerial data were continuous; ship-based data were converted separately into a continuous transect to the extent possible. From the digitized survey data, the distributions of effort and of marine bird species were mapped into 5 minute x 5 minute latitude x longitude cells using CDAS, a custom geographic information system for analyzing marine bird and mammal surveys (MMS-CDAS 2001). The length and width of the survey trackline in a given cell (estimated trackline width varied by platform, depending on speed and height above water) were used to estimate the area sampled. The number of marine birds seen in a cell was then divided by the area sampled in the cell to estimate density. If a cell was censused more than once, densities were averaged, with adjustment made for effort. Although the at-sea data span the years 1980-2001, data are not available for all seasons in all years. For the Upwelling Season, data are from 1980-1982 and 1985-2001. For the Oceanic Season, data are from 1980-1982, 1991 and 1994-2001. For the Davidson Current Season, data are from 1980-1986 and 1991-2001. All data sources were thoroughly checked for accuracy, consistency and completeness. Accuracy analyses were not applicable to this data set and therefore not produced.

All shapefile cells have attribute information.

All shapefile attributes were checked for consistency of appropriate range values. The at-sea density data, from which this shapefile was created, are the result of a synthesis of data from eight shipboard and aerial survey programs conducted in the study area in the years 1980-2001. Observation and trackline data from these studies were converted to a common format. All aerial data were continuous; ship-based data were converted separately into a continuous transect to the extent possible. From the digitized survey data, the distributions of effort and of marine bird species were mapped into 5 minute x 5 minute latitude x longitude cells using CDAS, a custom geographic information system for analyzing marine bird and mammal surveys (MMS-CDAS 2001). The length and width of the survey trackline in a given cell (estimated trackline width varied by platform, depending on speed and height above water) were used to estimate the area sampled. The number of marine birds seen in a cell was then divided by the area sampled in the cell to estimate density. If a cell was censused more than once, densities were averaged, with adjustment made for effort. Although the at-sea data span the years 1980-2001, data are not available for all seasons in all years. For the Upwelling Season, data are from 1980-1982 and 1985-2001. For the Oceanic Season, data are from 1980-1982, 1991 and 1994-2001. For the Davidson Current Season, data are from 1980-1986 and 1991-2001. All data sources were thoroughly checked for accuracy, consistency and completeness. Accuracy analyses were not applicable to this data set and therefore not produced/