diff --git a/lib/controllers/v1/observations_controller.js b/lib/controllers/v1/observations_controller.js
index 3747d877..62af3101 100644
--- a/lib/controllers/v1/observations_controller.js
+++ b/lib/controllers/v1/observations_controller.js
@@ -235,6 +235,7 @@ ObservationsController.elasticResults = async function observationElasticResults
     && ( _.isEmpty( query.inverse_filters ) || excludingOnlyUserIDs )
     && _.isEmpty( query.grouped_inverse_filters )
     && _.isEqual( query.sort, { created_at: "desc" } )
+    && _.isEmpty( req.query.aggs )
   ) {
     const sourceParams = util.sourceParams( returnOnlyID ? ["id"] : {
       includes: opts.includes,
@@ -1238,8 +1239,8 @@ ObservationsController.observationsObserverCounts = async req => {
     };
     // attempting to account for inaccurate counts for queries with a small size
     // see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#search-aggregations-bucket-terms-aggregation-shard-size
-    if ( ( ( aggSize * 1.5 ) + 10 ) < 200 ) {
-      countQuery.aggs.top_observers.terms.shard_size = 200;
+    if ( ( ( aggSize * 1.5 ) + 10 ) < 500 ) {
+      countQuery.aggs.top_observers.terms.shard_size = 500;
     }
   }
   countQuery.per_page = 0;
@@ -1289,8 +1290,8 @@ ObservationsController.observationsSpeciesObserverCounts = async req => {
     };
     // attempting to account for inaccurate counts for queries with a small size
     // see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#search-aggregations-bucket-terms-aggregation-shard-size
-    if ( ( ( aggSize * 1.5 ) + 10 ) < 200 ) {
-      countQuery.aggs.user_taxa.terms.shard_size = 200;
+    if ( ( ( aggSize * 1.5 ) + 10 ) < 500 ) {
+      countQuery.aggs.user_taxa.terms.shard_size = 500;
     }
     if ( aggSize > 0 ) {
       countQuery.aggs.user_taxa.aggs = {
diff --git a/lib/controllers/v1/taxa_controller.js b/lib/controllers/v1/taxa_controller.js
index 9d4bd11f..e6b6255e 100644
--- a/lib/controllers/v1/taxa_controller.js
+++ b/lib/controllers/v1/taxa_controller.js
@@ -20,6 +20,9 @@ TaxaController.show = async req => {
     throw util.httpError( 422, "Too many IDs" );
   }
   const filters = [{ terms: { id: ids } }];
+  if ( req.query.rank_level ) {
+    filters.push( esClient.termFilter( "rank_level", req.query.rank_level ) );
+  }
   return TaxaController.searchQuery( req, {
     filters,
     details: true,
diff --git a/lib/views/swagger_v1.yml.ejs b/lib/views/swagger_v1.yml.ejs
index 93efd08e..982a68b6 100644
--- a/lib/views/swagger_v1.yml.ejs
+++ b/lib/views/swagger_v1.yml.ejs
@@ -1691,6 +1691,7 @@ paths:
         corresponding taxa. A maximum of 30 results will be returned
       parameters:
         - $ref: "#/parameters/path_multi_id"
+        - $ref: "#/parameters/rank_level"
       tags:
         - Taxa
       responses:
diff --git a/openapi/paths/v2/taxa/{id}.js b/openapi/paths/v2/taxa/{id}.js
index 1dc7a184..81c267e4 100644
--- a/openapi/paths/v2/taxa/{id}.js
+++ b/openapi/paths/v2/taxa/{id}.js
@@ -22,6 +22,7 @@ module.exports = sendWrapper => {
           .meta( { in: "path" } )
           .required( )
       ),
+      transform( Joi.array( ).items( Joi.number( ) ).label( "rank_level" ).meta( { in: "query" } ) ),
       transform( Joi.string( ).label( "fields" ).meta( { in: "query" } ) ),
       transform( Joi.string( ).label( "X-HTTP-Method-Override" ).meta( { in: "header" } ) )
     ],
diff --git a/openapi/schema/request/taxa_search.js b/openapi/schema/request/taxa_search.js
index 3e81c773..edbd1340 100644
--- a/openapi/schema/request/taxa_search.js
+++ b/openapi/schema/request/taxa_search.js
@@ -32,7 +32,7 @@ module.exports = Joi.object( ).keys( {
     "variety",
     "form"
   ) ),
-  rank_level: Joi.number( ),
+  rank_level: Joi.array( ).items( Joi.number( ) ),
   id_above: Joi.number( ).integer( ),
   id_below: Joi.number( ).integer( ),
   per_page: Joi.number( ).integer( ),
diff --git a/test/integration/v1/observations.js b/test/integration/v1/observations.js
index bff8fd7c..9a54da9e 100644
--- a/test/integration/v1/observations.js
+++ b/test/integration/v1/observations.js
@@ -1329,6 +1329,13 @@ describe( "Observations", ( ) => {
       } ).expect( "Content-Type", /json/ )
         .expect( 200, done );
     } );
+
+    it( "can filter on id alone", function ( done ) {
+      request( this.app ).get( "/v1/observations/observers?id=1" ).expect( res => {
+        expect( res.body.total_results ).to.eq( 1 );
+      } ).expect( "Content-Type", /json/ )
+        .expect( 200, done );
+    } );
   } );
 
   describe( "species_counts", ( ) => {